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Studies on the Ripening Aspects and Fruit Quality of Date Palm
(Phoenix dactylifera L.) Cvs. “Hillawi and Khadrawi”
By
IMTIAZ HUSSAIN
Regd. No. 2002-ag-1450
M.Sc. (Hons.) Horticulture
A thesis submitted in the partial fulfillment of the requirement for degree of
Doctor of Philosophy
in
Horticulture
Faculty of Agriculture,
UNIVERSITY OF AGRICULTURE,
FAISALABAD (PAKISTAN)
2015
DECLARATION
I hereby declare that contents of thesis, “Studies on the ripening aspects and fruit
quality of date palm (Phoenix dactylifera L.) Cvs. Hillawi and Khadrawi” are the
product of my own research and no part has been copied from any published source
(except the references, standard mathematical model/equations/formulate/protocols etc.).
I further declare that this work has not been submitted for award of any other
diploma/degree. The university may take action if the information provided is found
inaccurate at any stage (in case of any default, the scholar will be proceeded against as
per HEC plagiarism policy).
Imtiaz Hussain
(2002-ag-1450)
The Controller of Examinations,
University of Agriculture,
Faisalabad, Pakistan.
We the supervisory committee, certify that the contents and form of the thesis submitted
by Mr. Imtiaz Hussain, Reg. No. 2002-ag-1450 have been found satisfactory and
recommend that it be processed for evaluation by external examiner (s) for the award of
degree.
SUPERVISORY COMMITTEE
1. Supervisor ___________________________________
(Dr. Saeed Ahmad)
2. Member ___________________________________
(Dr. Muhammad Amjad)
3. Member ___________________________________
(Dr. Rashid Ahmad)
OPENING
HE IS THE FIRST
HE IS THE LAST HE IS THE MANIFEST
HE IS THE HIDDEN
&
HE KNOWS EVERY THING
HE BRINGS THE NIGHT INTO THE DAY
&
BRINGS THE DAY INTO THE NIGHT
&
HE KNOWS THE THOUGHTS OF THE HEARTS
S. Al-HADDID-385 (AL-QURAN)
Dedicated to
My Mother
My Father
My Sister
&
My Brothers
i
ACKNOWLEDGEMENTS
All the praises are credited to the sole creator of the entire universe ALMIGHTY
ALLAH, The Most Beneficent, The Most Merciful and The Most Compassionate, Who
granted me the power of vision and wisdom to unknot the mysteries of the universe in a
more systematic manner what people call it SCIENCE. And only by the grace of
ALLAH, I was capable to make this material contribution to already existing ocean of
knowledge. I invoke Allah’s blessings and peace for my beloved Prophet Hazrat
MOHAMMAD (Peace Be Upon Him), who is eternally present torch of direction and
knowledge for humanity as a whole and whose honorable and spiritual teachings
enlightened my heart, soul and mind.
I desire to widen most sincere thanks and deep sense of obligations to my supervisor, Dr.
Saeed Ahmad (Associate Professor) Institute of Horticultural Sciences. This manuscript
has found its way to a significant close due to his energetic supervision, and masterly
advice. I feel much happiness to utter the heartiest gratitude and sincere admiration to
Prof. Dr. Muhammad Amjad, Institute of Horticultural Sciences and Prof. Dr. Rashid
Ahmad for their generous guidance, affectionate behavior, cooperation, priceless
suggestions and moral support throughout the course of my studies.
This work was impossible without the infrastructure, facilities, and technical support
provided by “Institute of Horticultural Sciences” University of Agriculture, Faisalabad,
Pakistan, for which I am highly thankful with the core of my heart to the Director ‘Prof.
Dr. Muhammad Aslam Pervez (Late)’, faculty and staff of the Institute.
With deep sense of devotion, I wish to thank Ch. Muhammad Azhar (Director AARI)
and Mr. Abdur Rahim Khan (Research Officer), Post-harvest Research Centre Ayub
Agriculture Research Institute, Faisalabad, for his kind help and support during the
research work. I am also thankful to Pomology Lab staff (Shakil Zahid, Shakeel Latif and
M. Farhan Khalid) for their prayers and nice cooperation in lab work during the whole
period of study.
With deep sense of devotion, I wish to thank my primary education teachers (Hafiz Saif
Ullah, Ustad Mubarik, Ustad Bilal, Ustad Saeed Ahmad) for their good and valuable
initial school education, my University fellows (Dr. Waseem Ahmad, Dr. Iqbal Hussain,
Dr. Tariq Aziz, Dr. Abdul Manan, Dr. Liaqat Ali, M. Tehseen Malik, Dr. Safdar Bashir,
Dr. Adnan Bukhari, Ahmad Mustafa, Amer Farooq, M. Farooq Ahmad, M. Ishaq
Ahmad), my cousins (M. Nadir, M. Tanveer, Dr. Hassan Iqbal, M. Shakeel Tariq), my
friends (Asghar Hussain, M. Yousaf, M. Asif, M. Majeed) and all those who remember
me in their prayers.
I feel my proud privilege to mention the feelings of obligations towards my affectionate
parents, my brothers (Hafiz Khuda Bakhsh, M. Ramzan, Allah Bakhsh, M. Sajjad
Hussain, Ijaz Hussain and Fiaz Hussain), my beloved Sister, nephews and nieces for
their love, affection and prayers which enable me to acquire this long adhered aim.
I am also thankful to the Higher Education Commission, Government of Pakistan for
awarding me the financial assistance as PhD Indigenous Fellowship Programme to
achieve this goal.
Imtiaz Hussain
ii
TABLE OF CONTENTS Chapter # Title Page #
Acknowledgements i
Table of contents ii
List of tables xi
List of figures xiii
List of slides xxi
List of symbols and abbreviations xxii
Abstract 1
1 Introduction 3
2 Review of literature 7
2.1 Introduction 7
2.2 Historical milieu of date palm cultivation 7
2.3 Significance of date palm 8
2.3.1 Religious and cultural significance 9
2.3.2 Nutritional significance 9
2.3.3 Biological and curative significance 10
2.4 Nutritional composition of date fruit 11
2.4.1 Sugars composition 11
2.4.2 Phytonutritional composition 13
2.4.2.1 Antioxidants composition 13
2.4.2.2 Phenolics composition 14
2.4.2.3 Flavonoids composition 14
2.4.2.4 Polyphenols composition 14
2.5 Activity of enzymes during date fruit maturation 15
2.6 Fruits classification on the basis of ripening 16
2.6.1 Climacteric fruits 16
2.6.2 Non climacteric fruits 17
2.7 Fruit ripening mechanism 17
2.8 Date fruit maturation and development 17
2.8.1 Hababouk stage 18
2.8.2 Kimri stage 18
2.8.3 Khalal stage 18
iii
2.8.4 Rutab stage 19
2.8.5 Tamar stage 19
2.9 Monsoon rains and dates industry 22
2.10 Fruit ripening agents 22
2.10.1 Ethephon (2-chloroethyl-phosphonic acid) 22
2.10.1.1 Pre-harvest ethephon application 23
2.10.1.2 Post-harvest ethephon application 25
2.10.2 Application of NaCl and acetic acid 26
2.11 Hot water applications 27
2.12 Application of thinning practices 30
3 Material and methods 32
3.1 Experimental site description 33
3.2 Experimental material 33
3.3 Experimental details 33
3.3.1a Experiment-1a: Evaluating the potential of ethephon on
ripening acceleration and fruit quality of date palm at kimri
stage
33
3.3.1.1a Method of spray 34
3.3.1.2a Method of injection 34
3.3.1.3a Fruit harvesting 34
3.3.1.b Experiment-1b: Effectiveness of ethephon on the ripening
acceleration and physico-chemical characteristics of date
palm at khalal stage
34
3.3.1.1b Methodology 34
3.3.2 Experiment-2: Exploring the role of thinning practices on
the ripening and fruit quality of date palm
37
3.3.2.1 Method and time of thinning 37
3.3.2.2 Fruit harvesting 37
3.3.3 Experiment-3: Ripening and quality assessment of date
palm fruit by the influence of hot water treatment
39
3.3.3.1 Fruit collection and hot water treatments procedure 39
3.3.4 Experiment-4: Effects of different chemicals on the ripening
behavior and fruit quality of date palm
39
iv
3.3.4.1 Fruit collection and treatments procedure 39
3.3.5 Experiment-5: Sun-drying techniques (SDTs) affected the
fruit quality attributes of dates picked at rutab stage cv.
Hillawi.
40
3.3.5.1 Fruit collection and treatments procedure 40
3.4 Detail of field work (observations recorded) 40
3.4.1 External/physical observations recorded 40
3.4.1.1 Time taken to reach the fruit at final kimri stage (days) 40
3.4.1.2 Time taken to reach the fruit at final khalal stage (days) 40
3.4.1.3 Time taken to reach the fruit at rutab stage (days) 41
3.4.1.4 Time taken to reach the fruit at tamar stage (days) 41
3.4.1.5 Rutab fruit yield per bunch (kg) 41
3.4.1.6 Uniform fruit ripening index (%) 41
3.4.1.7 Fruit weight (g) 41
3.4.1.8 Fruit length (mm) 41
3.4.1.9 Fruit width (mm) 41
3.4.1.10 Fruit flesh weight (g) 41
3.4.1.11 Fruit stone weight (g) 41
3.4.1.12 Fruit weight loss (%) 42
3.4.2 Biochemical analysis 42
3.4.2.1 Moisture determination (%) 42
3.4.2.2 Total soluble solids concentration (oBrix) 42
3.4.2.3 Ascorbic acid (mg 100 g-1
) 42
3.4.2.4 Total titratable acidity (%) 42
3.4.2.5 Total tannin (%) 43
3.4.2.6 Total phenolics (mg GAE/100g) 43
3.4.2.7 Total antioxidants (%) 43
3.4.2.8 Total flavonoids (mg CEQ/100 ) 43
3.4.2.9 Estimation of sugars through HPLC 44
3.4.3 Organoleptic evaluation 44
3.5 Statistical analysis 45
4 Results and discussion 46
v
4.1a Study-1 Evaluating the potential of ethephon on ripening
acceleration and fruit quality of date palm at kimri stage
46
4.1.1a Results 46
4.1.1.1a Fruit maturity/ripening traits 46
4.1.1.1.1a Time taken to reach the fruit at late khalal stage (days) 46
4.1.1.1.2a Time taken to reach the fruit at rutab stage (days) 46
4.1.1.1.3a Rutab fruit yield per bunch (kg) 47
4.1.1.1.4a Uniform fruit ripening index (%) 47
4.1.1.2a Fruit physical traits 50
4.1.1.2.1a Fruit weight (g) 50
4.1.1.2.2a Fruit length (mm) 50
4.1.1.2.3a Fruit width (mm) 50
4.1.1.2.4a Fruit flesh weight (g) 50
4.1.1.2.5a Fruit pit weight (g) 50
4.1.1.3a Fruit biochemical traits 53
4.1.1.3.1a Fruit moisture content (%) 53
4.1.1.3.2a Total soluble solids concentration (oBrix) 53
4.1.1.3.3a Total titratable acidity (%) 54
4.1.1.3.4a Ascorbic acid (mg 100 g-1
) 54
4.1.1.3.5a Glucose (%) 57
4.1.1.3.6a Fructose (%) 57
4.1.1.3.7a Sucrose (%) 57
4.1.1.3.8a Reducing sugars (%) 58
4.1.1.3.9a Total sugars (%) 58
4.1.1.4a Fruit phytonutritional traits 61
4.1.1.4.1a Total phenolics (mg GAE1/00 g) 61
4.1.1.4.2a Total flavonoids (mg CEQ/100 g) 61
4.1.1.4.3a Total tannins (%) 62
4.1.1.4.4a Total antioxidants (%) 62
4.1b Study-1 Effectiveness of ethephon on the ripening
acceleration and physico-chemical characteristics of date
palm at khalal stage
65
vi
4.1.1b Results 65
4.1.1.1b Fruit maturity/ripening traits 65
4.1.1.1.1b Time taken to reach the fruit at late khalal stage (days) 65
4.1.1.1.2b Time taken to reach the fruit at rutab stage (days) 65
4.1.1.1.3b Rutab fruit yield per bunch (kg) 66
4.1.1.1.4b Uniform fruit ripening index (%) 66
4.1.1.2b Fruit physical traits 69
4.1.1.2.1b Fruit weight (g) 69
4.1.1.2.2b Fruit length (mm) 69
4.1.1.2.3b Fruit width (mm) 69
4.1.1.2.4b Fruit flesh weight (g) 69
4.1.1.2.5b Fruit pit weight (g) 69
4.1.1.3b Fruit biochemical traits 72
4.1.1.3.1b Fruit moisture content (%) 72
4.1.1.3.2b Total soluble solids concentration (oBrix) 72
4.1.1.3.3b Total titratable acidity (%) 73
4.1.1.3.4b Ascorbic acid (mg 100 g-1
) 73
4.1.1.3.5b Glucose (%) 76
4.1.1.3.6b Fructose (%) 76
4.1.1.3.7b Sucrose (%) 76
4.1.1.3.8b Reducing sugars (%) 76
4.1.1.3.9b Total sugars (%) 76
4.1.1.4b Fruit phytonutritional traits 79
4.1.1.4.1b Total phenolics (mg GAE1/00 g) 79
4.1.1.4.2b Total flavonoids (mg CEQ/100 g) 80
4.1.1.4.3b Total tannins (%) 80
4.1.1.4.4b Total antioxidants (%) 80
4.1.2 (a, b) Discussion 83
4.1.3 (a, b) Conclusion 88
4.2 Study-2 Exploring the role of thinning practices on the
ripening acceleration and fruit quality of date palm
89
4.2.1 Results 89
vii
4.2.1.1 Fruit maturity/ripening traits 89
4.2.1.1.1 Time taken from early kimri to final kimri stage (days) 89
4.2.1.1.2 Time taken from early kimri to late khalal stage (days) 89
4.2.1.1.3 Time taken from early kimri to rutab stage (days) 90
4.2.1.1.4 Rutab fruit yield per bunch (kg) 90
4.2.1.1.5 Uniform fruit ripening index (%) 91
4.2.2.1 Fruit physical traits 94
4.2.2.1.1 Fruit weight (g) 94
4.2.2.1.2 Fruit length (mm) 94
4.2.2.1.3 Fruit width (mm) 94
4.2.2.1.4 Fruit flesh weight (g) 95
4.2.2.1.5 Fruit pit weight (g) 95
4.2.3.1 Fruit biochemical traits 98
4.2.3.1.1 Fruit moisture content (%) 98
4.2.3.1.2 Total soluble solids concentration (oBrix) 98
4.2.3.1.3 Total titratable acidity (%) 99
4.2.3.1.4 Ascorbic acid (mg 100 g-1
) 99
4.2.3.1.5 Glucose (%) 102
4.2.3.1.6 Fructose (%) 102
4.2.3.1.7 Sucrose (%) 103
4.2.3.1.8 Reducing sugars (%) 103
4.2.3.1.9 Total sugars (%) 104
4.2.4.1 Fruit phytonutritional traits 107
4.2.4.1.1 Total phenolics (mg GAE1/00 g) 107
4.2.4.1.2 Total flavonoids (mg CEQ/100 g) 107
4.2.4.1.3 Total tannins (%) 107
4.2.4.1.4 Total antioxidants (%) 108
4.2.2 Discussion 111
4.2.3 Conclusion 114
4.3 Study-3 Ripening and quality assessment of date palm fruit
by the influence of hot water treatment
115
4.3.1 Results 115
viii
4.3.1.1 Fruit physical traits 115
4.3.1.1.1 Time taken to reach the fruit at tamar stage (days) 115
4.3.1.1.2 Uniform fruit ripening index (%) 115
4.3.1.1.3 Fruit weight loss (%) 116
4.3.1.1.4 Fruit moisture content (%) 116
4.3.1.1.5 Fruit flesh weight (g) 116
4.3.1.1.6 Fruit pit weight (g) 117
4.3.1.2 Fruit biochemical traits 123
4.3.1.2.1 Total soluble solids concentration (oBrix) 123
4.3.1.2.2 Total titratable acidity (%) 123
4.3.1.2.3 Ascorbic acid (mg 100 g-1
) 124
4.3.1.2.4 Glucose (%) 126
4.3.1.2.5 Fructose (%) 126
4.3.1.2.6 Sucrose (%) 127
4.3.1.2.7 Reducing sugars (%) 127
4.3.1.2.8 Total sugars (%) 128
4.3.1.3 Fruit phytonutritional traits 131
4.3.1.3.1 Total phenolics (mg GAE1/00 g) 131
4.3.1.3.2 Total flavonoids (mg CEQ/100 g) 131
4.3.1.3.3 Total tannins (%) 131
4.3.1.3.4 Total antioxidants (%) 132
4.3.1.4 Organoleptic evaluation 135
4.3.1.4.1 Color score 135
4.3.1.4.2 Taste score 135
4.3.1.4.3 Texture score 135
4.3.1.4.4 Firmness score 136
4.3.1.4.5 Astringency score 136
4.3.1.4.6 Overall acceptability score 137
4.3.2 Study-3 Effects of different chemicals on the ripening
behavior and fruit quality of date palm
141
4.3.2.1 Results 141
4.3.2.1.1 Fruit physical traits 141
ix
4.3.2.1.1.1 Uniform fruit ripening index (%) 141
4.3.2.1.1.2 Fruit weight loss (%) 141
4.3.2.1.1.3 Fruit moisture content (%) 142
4.3.2.1.1.4 Fruit flesh weight (g) 142
4.3.2.1.1.5 Fruit pit weight (g) 142
4.3.2.2.1 Fruit biochemical traits 145
4.3.2.2.1.1 Total soluble solids concentration (oBrix) 145
4.3.2.2.1.1 Total titratable acidity (%) 145
4.3.2.2.1.3 Ascorbic acid (mg 100 g-1
) 146
4.3.2.2.1.4 Glucose (%) 148
4.3.2.2.1.5 Fructose (%) 148
4.3.2.2.1.6 Sucrose (%) 149
4.3.2.2.1.7 Reducing sugars (%) 149
4.3.2.2.1.8 Total sugars (%) 150
4.3.2.3.1 Fruit phytonutritional traits 153
4.3.2.3.1.1 Total phenolics (mg GAE1/00 g) 153
4.3.2.3.1.2 Total flavonoids (mg CEQ/100 g) 153
4.3.2.3.1.3 Total tannins (%) 153
4.3.2.3.1.4 Total antioxidants (%) 154
4.3.2.4.1 Organoleptic evaluation 156
4.3.2.4.1.1 Color score 156
4.3.2.4.1.2 Taste score 156
4.3.2.4.1.3 Texture score 157
4.3.2.4.1.4 Firmness score 157
4.3.2.4.1.5 Astringency score 157
4.3.2.4.1.6 Overall acceptability score 158
4.3.2 (1, 2) Discussion 162
4.3.3 (1, 2) Conclusion 167
4.4 Study-4 Sun-drying techniques (SDTs) affected the fruit
quality attributes of dates picked at rutab stage cv. Hillawi
168
4.4.1 Results 168
4.4.1.1 Fruit weight loss (%) 168
x
4.4.1.2 Fruit moisture content (%) 168
4.4.1.3 Total soluble solids concentration (oBrix) 168
4.4.1.4 Total titratable acidity (%) 169
4.4.1.5 Reducing sugars (%) 169
4.4.1.6 Total sugars (%) 169
4.4.1.7 Total phenolics (mg GAE/100 g) 173
4.4.1.8 Total flavonoids (mg CEQ/100 g) 173
4.4.1.9 Total antioxidants (%) 173
4.4.1.10 Total tannins (%) 173
4.4.2 Discussion 176
4.4.3 Conclusion 178
5 General discussion: Conclusions: Recommendations 181
5.1 General discussion 181
5.2 Conclusions 186
5.3 Recommendations 186
4.5 Future research needed 187
LITERATURE CITED 188
xi
LIST OF TABLES Table # Title Page #
3.1 Organoleptic evaluation of Hillawi and Khadrawi date palm
cultivars.
45
4.1 Effects of different strands thinning intensities on time taken
(days) from early kimri to late kimri stage of Hillawi and
Khadrawi date palm fruit.
91
4.2 Effects of different strands thinning intensities on time taken
(days) from early kimri to late khalal stage of Hillawi and
Khadrawi date palm fruit.
91
4.3 Effects of different strands thinning intensities on time taken
(days) from early kimri to rutab stage of Hillawi and Khadrawi
date palm fruit.
91
4.4 Effects of different strands thinning intensities on rutab fruit
yield (kg) per bunch of Hillawi and Khadrawi date palm fruit.
93
4.5 Effects of different strands thinning intensities on uniform fruit
ripening index (%) of Hillawi and Khadrawi date palm fruit.
93
4.6 Effects of different strands thinning intensities on individual fruit
weight (g) of Hillawi and Khadrawi date palm fruit.
96
4.7 Effects of different strands thinning intensities on fruit length
(mm) of Hillawi and Khadrawi date palm fruit.
96
4.8 Effects of different strands thinning intensities on fruit width
(mm) of Hillawi and Khadrawi date palm fruit.
97
4.9 Effects of different strands thinning intensities on fruit flesh
weight (g) of Hillawi and Khadrawi date palm fruit.
97
4.10 Effects of different strands thinning intensities on fruit pit weight
(g) of Hillawi and Khadrawi date palm fruit.
98
4.11 Effects of different strands thinning intensities on fruit moisture
content (%) of Hillawi and Khadrawi date palm fruit.
100
4.12 Effects of different strands thinning intensities on total soluble
solids concentration (oBrix) of Hillawi and Khadrawi date palm
fruit.
101
4.13 Effects of different strands thinning intensities on titratable 101
xii
acidity (%) of Hillawi and Khadrawi date palm fruit.
4.14 Effects of different strands thinning intensities on ascorbic acid
(mg 100 g-1
) of Hillawi and Khadrawi date palm fruit.
102
4.15 Effects of different strands thinning intensities on glucose (%) of
Hillawi and Khadrawi date palm fruit.
104
4.16 Effects of different strands thinning intensities on fructose (%) of
Hillawi and Khadrawi date palm fruit.
105
4.17 Effects of different strands thinning intensities on sucrose (%) of
Hillawi and Khadrawi date palm fruit.
105
4.18 Effects of different strands thinning intensities on reducing
sugars (%) of Hillawi and Khadrawi date palm fruit.
106
4.19 Effects of different strands thinning intensities on total sugars
(%) of Hillawi and Khadrawi date palm fruit.
106
4.20 Effects of different strands thinning intensities on total phenolics
(mg GAE/100 g) of Hillawi and Khadrawi date palm fruit.
109
4.21 Effects of different strands thinning intensities on total
flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi date palm
fruit.
109
4.22 Effects of different strands thinning intensities on total tannins
(%) of Hillawi and Khadrawi date palm fruit.
110
4.23 Effects of different strands thinning intensities on total
antioxidants (%) of Hillawi and Khadrawi date palm fruit.
110
xiii
LIST OF FIGURES Figure # Title Page #
3.1 Average meteorological data during two seasons (2011-2012) at
experimental site of date palm orchard.
45
4.1a Effects of different ethephon concentrations (spray and injection)
on time taken (days) from final kimri to late khalal stage of
Hillawi and Khadrawi date palm fruit ± S.E.
48
4.2a Effects of different ethephon concentrations (spray and injection)
on time taken (days) from final kimri to rutab stage of Hillawi
and Khadrawi date palm fruit ± S.E.
48
4.3a Effects of different ethephon concentrations (spray and injection)
on rutab fruit yield per bunch (kg) of Hillawi and Khadrawi date
palm fruit ± S.E.
49
4.4a Effects of different ethephon concentrations (spray and injection)
on uniform fruit ripening index (%) of Hillawi and Khadrawi
date palm fruit ± S.E.
49
4.5a Effects of different ethephon concentrations (spray and injection)
on fruit weight (g) of Hillawi and Khadrawi date palm ± S.E.
51
4.6a Effects of different ethephon concentrations (spray and injection)
on fruit length (mm) of Hillawi and Khadrawi date palm ± S.E.
51
4.7a Effects of different ethephon concentrations (spray and injection)
on fruit width (mm) of Hillawi and Khadrawi date palm ± S.E.
52
4.8a Effects of different ethephon concentrations (spray and injection)
on flesh weight (g) of Hillawi and Khadrawi date palm fruit ±
S.E.
52
4.9a Effects of different ethephon concentrations (spray and injection)
on pit weight (g) of Hillawi and Khadrawi date palm fruit ± S.E.
53
4.10a Effects of different ethephon concentrations (spray and injection)
on fruit moisture content (%) of Hillawi and Khadrawi date palm
fruit ± S.E.
55
4.11a Effects of different ethephon concentrations (spray and injection)
on total soluble solids concentration (oBrix) of Hillawi and
Khadrawi date palm fruit ± S.E.
55
xiv
4.12a Effects of different ethephon concentrations (spray and injection)
on titratable acidity (%) of Hillawi and Khadrawi date palm fruit
± S.E.
56
4.13a Effects of different ethephon concentrations (spray and injection)
on ascorbic acid (mg 100 g-1
) of Hillawi and Khadrawi date palm
fruit ± S.E.
56
4.14a Effects of different ethephon concentrations (spray and injection)
on glucose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
59
4.15a Effects of different ethephon concentrations (spray and injection)
on fructose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
59
4.16a Effects of different ethephon concentrations (spray and injection)
on sucrose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
60
4.17a Effects of different ethephon concentrations (spray and injection)
on reducing sugar (%) of Hillawi and Khadrawi date palm fruit ±
S.E.
60
4.18a Effects of different ethephon concentrations (spray and injection)
on total sugars (%) of Hillawi and Khadrawi date palm fruit ±
S.E.
61
4.19a Effects of different ethephon concentrations (spray and injection)
on total phenolics (mg GAE/100 g) of Hillawi and Khadrawi date
palm fruit ± S.E.
63
4.20a Effects of different ethephon concentrations (spray and injection)
on total flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi
date palm fruit ± S.E.
63
4.21a Effects of different ethephon concentrations (spray and injection)
on total tannins (%) of Hillawi and Khadrawi date palm fruit ±
S.E.
64
4.22a Effects of different ethephon concentrations (spray and injection)
on total antioxidants (%) of Hillawi and Khadrawi date palm
fruits ± S.E.
64
4.23b Effects of different ethephon concentrations (spray and injection)
on time taken (days) from early khalal to late khalal stage of
Hillawi and Khadrawi date palm fruit ± S.E.
67
xv
4.24b Effects of different ethephon concentrations (spray and injection)
on time taken (days) from early khalal to rutab stage of Hillawi
and Khadrawi date palm fruit ± S.E.
67
4.25b Effects of different ethephon concentrations (spray and injection)
on rutab fruit yield per bunch (kg) of Hillawi and Khadrawi date
palm fruit ± S.E.
68
4.26b Effects of different ethephon concentrations (spray and injection)
on uniform fruit ripening index (%) of Hillawi and Khadrawi
date palm fruit ± S.E.
68
4.27b Effects of different ethephon concentrations (spray and injection)
on individual fruit weight (g) of Hillawi and Khadrawi date palm
± S.E.
70
4.28b Effects of different ethephon concentrations (spray and injection)
on fruit length (mm) of Hillawi and Khadrawi date palm ± S.E.
70
4.29b Effects of different ethephon concentrations (spray and injection)
on fruit width (mm) of Hillawi and Khadrawi date palm ± S.E.
71
4.30b Effects of different ethephon concentrations (spray and injection)
on flesh weight (g) of Hillawi and Khadrawi date palm fruit ±
S.E.
71
4.31b Effects of different ethephon concentrations (spray and injection)
on pit weight (g) of Hillawi and Khadrawi date palm fruit ± S.E.
72
4.32b Effects of different ethephon concentrations (spray and injection)
on moisture content (%) of Hillawi and Khadrawi date palm fruit
± S.E.
74
4.33b Effects of different ethephon concentrations (spray and injection)
on total soluble solids concentration (oBrix) of Hillawi and
Khadrawi date palm fruit ± S.E.
74
4.34b Effects of different ethephon concentrations (spray and injection)
on total titratable acidity (%) of Hillawi and Khadrawi date palm
fruit ± S.E.
75
4.35b Effects of different ethephon concentrations (spray and injection)
on ascorbic acid (mg 100 g-1
) of Hillawi and Khadrawi date palm
fruit ± S.E.
75
xvi
4.36b Effects of different ethephon concentrations (spray and injection)
on glucose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
77
4.37b Effects of different ethephon concentrations (spray and injection)
on fructose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
77
4.38b Effects of different ethephon concentrations (spray and injection)
on sucrose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
78
4.39b Effects of different ethephon concentrations (spray and injection)
on reducing sugars (%) of Hillawi and Khadrawi date palm fruit
± S.E.
78
4.40b Effects of different ethephon concentrations (spray and injection)
on total sugars (%) of Hillawi and Khadrawi date palm fruit ±
S.E.
79
4.41b Effects of different ethephon concentrations (spray and injection)
on total phenolics (mg GAE/100 g) of Hillawi and Khadrawi date
palm fruit ± S.E.
81
4.42b Effects of different ethephon concentrations (spray and injection)
on total flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi
date palm fruit ± S.E.
81
4.43b Effects of different ethephon concentrations (spray and injection)
on total tannins (%) of Hillawi and Khadrawi date palm fruit ±
S.E.
82
4.44b Effects of different ethephon concentrations (spray and injection)
on total antioxidants (%) of Hillawi and Khadrawi date palm fruit
± S.E.
82
4.45 Effects of hot water treatments at 65oC on time taken to tamar
stage (days) of Hillawi and Khadrawi date palm fruit ± S.E.
118
4.46 Effects of hot water treatments at 65oC on uniform fruit ripening
index (%) of Hillawi and Khadrawi date palm fruit ± S.E.
118
4.47 Effects of hot water treatments at 65oC on fruit weight loss (%)
of Hillawi and Khadrawi date palm fruit ± S.E.
119
4.48 Effects of hot water treatments at 65oC on moisture content (%)
of Hillawi and Khadrawi date palm fruit ± S.E.
119
4.49 Effects of hot water treatments at 65oC on flesh weight (%) of 120
xvii
Hillawi and Khadrawi date palm fruit ± S.E.
4.50 Effects of hot water treatments at 65oC on pit weight (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
120
4.51 Effects of hot water treatments at 65oC on total soluble solids
concentration (oBrix) of Hillawi and Khadrawi date palm fruit ±
S.E.
124
4.52 Effects of hot water treatments at 65oC on titratable acidity (%)
of Hillawi and Khadrawi date palm fruit ± S.E.
125
4.53 Effects of hot water treatments at 65oC on ascorbic acid (mg 100
g-1
) of Hillawi and Khadrawi date palm fruit ± S.E.
125
4.54 Effects of hot water treatments at 65oC on glucose (%) of Hillawi
and Khadrawi date palm fruit ± S.E.
128
4.55 Effects of hot water treatments at 65oC on fructose (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
129
4.56 Effects of hot water treatments at 65oC on sucrose (%) of Hillawi
and Khadrawi date palm fruit ± S.E.
129
4.57 Effects of hot water treatments at 65oC on reducing sugars (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
130
4.58 Effects of hot water treatments at 65oC on total sugars (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
130
4.59 Effects of hot water treatments at 65oC on total phenolics (mg
GAE/100 g) of Hillawi and Khadrawi date palm fruit ± S.E.
133
4.60 Effects of hot water treatments at 65oC on total flavonoids (mg
CEQ/100 g) of Hillawi and Khadrawi date palm fruit ± S.E.
133
4.61 Effects of hot water treatments at 65oC on total tannins (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
134
4.62 Effects of hot water treatments at 65oC on total antioxidants (%)
of Hillawi and Khadrawi date palm fruit ± S.E.
134
4.63 Effects of hot water treatments at 65oC on color score of Hillawi
and Khadrawi date palm fruit ± S.E.
138
4.64 Effects of hot water treatments at 65oC on taste score of Hillawi
and Khadrawi date palm fruit ± S.E.
138
4.65 Effects of hot water treatments at 65oC on texture score of 139
xviii
Hillawi and Khadrawi date palm fruit ± S.E.
4.66 Effects of hot water treatments at 65oC on firmness score of
Hillawi and Khadrawi date palm fruit ± S.E.
139
4.67 Effects of hot water treatments at 65oC on astringency score of
Hillawi and Khadrawi date palm fruit ± S.E.
140
4.68 Effects of hot water treatments at 65oC on overall acceptability
score of Hillawi and Khadrawi date palm fruit ± S.E.
140
4.69 Effects of different chemicals on uniform fruit ripening index
(%) of Hillawi and Khadrawi date palm fruit after incubation at
40±1oC for 72 h ± S.E.
143
4.70 Effects of different chemicals on fruit weight loss (%) of Hillawi
and Khadrawi date palm fruit after incubation at 40±1oC for 72 h
± S.E.
143
4.71 Effects of different chemicals on fruit moisture content (%) of
Hillawi and Khadrawi date palm fruit after incubation at 40±1oC
for 72 h ± S.E.
144
4.72 Effects of different chemicals on fruit flesh weight (g) of Hillawi
and Khadrawi date palm fruit after incubation at 40±1oC for 72 h
± S.E.
144
4.73 Effects of different chemicals on fruit pit weight (g) of Hillawi
and Khadrawi date palm fruit after incubation at 40±1oC for 72 h
± S.E.
145
4.74 Effects of different chemicals on total soluble solids
concentration (oBrix) of Hillawi and Khadrawi date palm fruit
after incubation at 40±1oC for 72 h ± S.E.
147
4.75 Effects of different chemicals on titratable acidity (%) of Hillawi
and Khadrawi date palm fruit after incubation at 40±1oC for 72 h
± S.E.
147
4.76 Effects of different chemicals on ascorbic acid (mg 100 g-1
) of
Hillawi and Khadrawi date palm fruit after incubation at 40±1oC
for 72 h ± S.E.
148
4.77 Effects of different chemicals on glucose (%) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ±
150
xix
S.E.
4.78 Effects of different chemicals on fructose (%) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ±
S.E.
151
4.79 Effects of different chemicals on sucrose (%) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ±
S.E.
151
4.80 Effects of different chemicals on reducing sugars (%) of Hillawi
and Khadrawi date palm fruit after incubation at 40±1oC for 72 h
± S.E.
152
4.81 Effects of different chemicals on total sugars (%) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ±
S.E.
152
4.82 Effects of different chemicals on total phenolics (mg GAE/100 g)
of Hillawi and Khadrawi date palm fruit after incubation at
40±1oC for 72 h ± S.E.
154
4.83 Effects of different chemicals on total flavonoids (mg CEQ/100
g) of Hillawi and Khadrawi date palm fruit after incubation at
40±1oC for 72 h ± S.E.
155
4.84 Effects of different chemicals on total tannins (%) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ±
S.E.
155
4.85 Effects of different chemicals on total antioxidants (%) of
Hillawi and Khadrawi date palm fruit after incubation at 40±1oC
for 72 h ± S.E.
156
4.86 Effects of different chemicals on color score after incubation at
40±1oC for 72 h ± S.E.
158
4.87 Effects of different chemicals on taste score after incubation at
40±1oC for 72 h ± S.E.
159
4.88 Effects of different chemicals on texture score after incubation at
40±1oC for 72 h ± S.E.
159
4.89 Effects of different chemicals on firmness score after incubation
at 40±1oC for 72 h ± S.E.
160
xx
4.90 Effects of different chemicals on astringency score after
incubation at 40±1oC for 72 h ± S.E.
160
4.91 Effects of different chemicals on overall acceptability score after
incubation at 40±1oC for 72 h ± S.E.
161
4.92 Effects of sun-drying techniques on weight loss (%) in the fruits
of Hillawi cultivar analyzed at tamar stage ± S.E.
170
4.93 Effects of sun-drying techniques on moisture content (%) in the
fruits of Hillawi cultivar analyzed at tamar stage ± S.E.
170
4.94 Effects of sun-drying techniques on total soluble solids
concentration (%) in the fruits of Hillawi cultivar analyzed at
tamar stage ± S.E.
171
4.95 Effects of sun-drying techniques on total titratable acidity (%) in
the fruits of Hillawi cultivar analyzed at tamar stage ± S.E.
171
4.96 Effects of sun-drying techniques on reducing sugars (%) in the
fruits of Hillawi cultivar analyzed at tamar stage ± S.E.
172
4.97 Effects of sun-drying techniques on total sugars (%) in the fruits
of Hillawi cultivar analyzed at tamar stage ± S.E.
172
4.98 Effects of sun-drying techniques on total phenolics (mg
GAE/100 g) in the fruits of Hillawi cultivar analyzed at tamar
stage ± S.E.
174
4.99 Effects of sun-drying techniques on total flavonoids (mg
CEQ/100 g) in the fruits of Hillawi cultivar analyzed at tamar
stage ± S.E.
174
4.100 Effects of sun-drying techniques on total antioxidants (%) in the
fruits of Hillawi cultivar analyzed at tamar stage ± S.E.
175
4.101 Effects of sun-drying techniques on total tannins (%) in the fruits
of Hillawi cultivar analyzed at tamar stage ± S.E.
175
xxi
LIST OF SLIDES Slide # Title Page #
2.1 Different edible stages of Khadrawi fruit. 20
2.2 Different edible stages of Hillawi fruit. 21
3.1 Mature fruit of date palm at final kimri stage cv. Hillawi. 32
3.2 Mature fruit of date palm at final kimri stage cv. Khadrawi. 32
3.3 Application of ethephon by foliar spray and injection. 35
3.4 Performing strands thinning practices at early kimri stage. 38
4.1 Effects of hot water treatment (HWT) on the ripening behavior of
Hillawi fruit under ambient conditions.
121
4.2 Effects of hot water treatment (HWT) on the ripening behavior of
Khadrawi fruit under ambient conditions.
122
4.3 Different steps involved in the processing of soft Hillawi dates
by modified sun-drying techniques.
179
xxii
LIST OF SYMBOLS AND ABBREVIATIONS Abbreviation Description
@ At the rate of o Degree
% Percent
µL Microliter (s)
$ United States Dollar
A Absorbance
≤ Less than or equal to
≥ Greater than or equal to
± Plus minus
AA Abscisic acid
AARI Ayub Agricultural Research Institute
ASF Agri. Support Fund
C2H2 Ethylene
Ca Calcium
Ca+2
Calcium ions
CEQ Catechin equivalents
cm Centimeter
CRD Completely randomized design
cv Cultivar (s)
DDH2O Double distilled water
DF Date fruit
DMRT Duncan’s Multiple Range Test
DPPH 2, 2, diphenyl-1-picrylhydrazyl
ELISA Enzyme-linked immunosorbent assay
et al. et alia
FAO Food and Agriculture Organization
FC Folin-Ciocalteu
Fe Iron
g Gram (s)
GAE Gallic acid equillents
GOP Government of Pakistan
h Hour
ha Hectare
HPLC High Performance Liquid Chromatograph
HW Hot water
HWD Hot water dipping
I Inhibition
i.e. Illud est
IC Inhibition concentration
IHS Institute of Horticultural Sciences
K Potassium
kg Kilogram
KPK Khyber Pakhtunkhaw
L Liter
L-1
Per liter
LC Liquid chromatography
xxiii
LSD Least significant difference
M Molarity
m/v Mass over volume
Mg Magnesium
mg Milligram
min Minute
ml Milliliter
mm Millimeter
mM Millimolar
Mt. Metric ton
N Normality
Na2CO3 Sodium carbonate
NaCl Sodium chloride
NaHCO3 Sodium bicarbonate
NaOH Sodium hydroxide
nm Nano-meter
ns Non-significant oC Degree Celsius
P Probability
PARS Post Graduate Agricultural Research Station
PE Pectin esterase
PG Polygalacturonase
PL Pectate lyases
ppm Parts per million
R.H Relative humidity
RCBD Randomized complete block design
RCS Removal of central strands
ReID Refractive index detector
S.E Standard error
SBI Sindh Board of Investment
SDT Sun-drying technique
SL Soluble liquid
SSC Soluble solids concentrate
STT Shortening of terminal tips
TA Total titratable acidity
TFC Total flavonoids contents
TPC Total phenolic contents
TSS Total soluble solids
UV Ultra violet
v/v Volume/volume
viz. Videlicet
vs. Versus
1
ABSTRACT
Date palm is an important fruit crop in the world as well as in Pakistan. It provides a rich
and quick energy source to humans and also plays a significant role in the social and
economic life of the people living in dry areas. Monsoon rains at the time of fruit
harvesting or ripening are very harmful and heavy fruit losses occur resulting rotting, fruit
drop and uneven fruit ripening. Unfortunately, in Pakistan serious losses occur due to
these rains at the time of fruit harvesting/ripening. The research work reported in this
manuscript was conducted in the Experimental Fruit Orchard Square Number 9 and Post
Graduate Agricultural Research Station (PARS) (Latitude 31o-26´ N, Longitude 73
o-06´ E
and Altitude 184.4 m), Institute of Horticultural Sciences, University of Agriculture
Faisalabad, Punjab Province, Pakistan. In the field studies, effectiveness of ethephon
application (foliar and injection) and strands thinning practices on ripening acceleration
and fruit quality of date palm were investigated and found that ethephon application with
spray showed superiority over injection method to accelerate the maturity and ripening
processes of date fruits in both Hillawi and Khadrawi cultivars. Fruit sprayed with
ethephon (4 ml/L and 2 ml/L) at final kimri and early khalal stages reached at rutab stage
13 and 6 days earlier and showed uniform fruit ripening indexes of 60.46 and 44.85% and
rutab fruit yield (6.29 and 4.37 kg ) per bunch with good fruit quality composition than
the untreated fruits. Second field experiment was conducted to explore the role of strands
thinning on maturity enhancement and fruit quality. Strands thinning practices were
carried out with following intensities (no thinning, 20% RCS (removal of central strands),
30% RCS, 20% STT (shortening of terminal tips), 30% STT, 20% RCS + 20% STT and
30% RCS + 30% STT) at early kimri stage (4 weeks after pollination). It was observed
that strands thinning practices improved quality characteristics than the fruit those were
untreated (without thinning) in both cultivars. Strands thinning intensity @ 30% RCS
alone resulted in 10 days earlier maturity and higher rutab yield of 5.22 kg per bunch and
more uniformly ripe fruit (76.28%) at rutab stage. The total soluble solids, ascorbic acid,
sugars (glucose, fructose and sucrose), total phenolic, total flavonoids and total
antioxidants were significantly improved while titratable acidity and total tannin contents
were decreased in thinned fruits. In post-harvest experiments, hot water exposures for 3
and 5 min at 65oC in Hillawi and Khadrawi cultivars reduce the fruit ripening period up to
6 days and produced uniformly ripened fruit (73.33 and 81.66%) with better quality and
higher acceptability of organoleptic scores marked by the panellists as compared to
2
untreated fruit. Acetic acid @ 3% showed higher uniform ripening index of 64.24% with
higher total soluble solids, sugars, total phenolic, total flavonoids, total antioxidants and
organoleptic properties after incubation at 40±1oC for 72 h. In the last study different sun
drying techniques were used for the curing of soft Hillawi dates. Among different sun-
drying techniques, SDT4 (DSE with removal in baskets and covered during night) proved
good regarding the fruit quality composition such as TSS, acidity, total sugar, reducing
sugar, total phenolics, total antioxidants, total flavonoids with lower amounts of total
tannin contents. In conclusion, a spray application of ethephon @ 4 ml/L at final kimri
stage, strands thinning @ 30% RCS alone at early kimri stage, hot water treatments at
khalal stage (3 min for Hillawi and 5 min for Khadrawi) and acetic acid @ 3% at khalal
stage showed better results to accelerate the fruit ripening period and produced higher
index of uniformly ripe fruits with good fruit quality composition in both date palm
cultivars. Among different sun-drying techniques in fruits harvested at rutab stage, SDT4
(DSE with removal in baskets and covered during night) proved good regarding the fruit
quality composition in Hillawi date palm cultivar. Uniformity in ripening gave extra
benefits and higher economic returns were achieved by adopting these technologies and it
provided higher economic return.
3
Chapter-1 INTRODUCTION
Date palm (Phoenix dactylifera L.) is a primeval plant and considered as a ‘symbol of
life’ in the desert oases of Arab world countries for centuries (Baliga et al., 2011). It is
monocotyledonous, dioecious in nature and belongs to family Palmaceae (Barrow, 1998).
Date palm has 14 recognized species; dactylifera is one of the most cultivated fruit crop
in world. Dactylifera is widely spread in the tropical and subtropical regions of Africa
and southern Asia with varied geographical, soil and climatic conditions (El-Hadrami et
al., 2011). The name of date palm originates from its fruit ‘Phoenix’ which means purple
or red in Greek and ‘dactylifera’ refers due to the finger like appearance of fruit bunches.
The morphology of male and female date palm plants varies according to the structure of
inflorescence. The flowers of both male and female are covered in a hard, fibrous sheath
that protects them from heat and sunlight at early growth stages during flower initiation or
development (Nixon and Carpenter, 1978; Vandercook et al., 1980).
Globally, date palm is grown in 37 countries with more than 2000 different cultivars (Ali-
Mohamed and Khamis, 2004). A large population of date palm trees is found in the
Arabian Gulf and North Africa with a small population in North American states
(California, Arizona and Mexico). Date palm requires high temperature of 35oC for
optimum pollen development, fruit set and ripening with low relative humidity. It requires
abundance of water drained from bottom of the soil or from surface irrigation through a
deep-rooted structure. The date palm grows well in almost less rain fall areas at North
latitude ranging from 9-39o with areas represented by Sahara desert in Africa and
Southern borders of Near East commonly known as Arabian Peninsula, Southern Iraq and
Jordan. A date palm garden can survive up to an average life of 40-50 years, but few are
still productive up to 150 years (Chao and Krueger, 2007).
Presently, global production, consumption and industrialization of date palm are
increasing constantly as noticed in main date palm producing states such as Egypt (1.37
million tons), Saudi Arabia (1.12 million tons), Iran (1.01 million tons), UAE (0.900
million tons), Algeria (0.690 million tons), Iraq (0.619 million tons) and Pakistan (0.557
million tons) (FAOSTAT, 2011). World area under date palm cultivation in 2009-10 was
1.3 million hectares (FAOSTAT, 2011). However, the area under cultivation had been
increased by 0.300 million ha during the last few decades. Gulf countries are the biggest
producer of dates having an area under cultivation of 0.833 million hectares followed by
4
Africa (0.416 million hectares) and North Africa (0.392 million hectares). In American
states and European Union, the date’s production holds just a few thousand hectares.
While, Middle East and North Africa are the main dates producing centers with an annual
production of 2.70 million tons. United States is at top rank regarding dates annual
production with an average of 67.09 tons ha-1
followed by North African countries on an
average of 64.97 tons ha-1
. Although a large number of production groves exist in the
Middle East but annual production is below the world average of 53.79 tons ha-1
(FAOSTAT, 2011). The Middle-East and North African countries account for almost
60% of total world’s production with the cultivation of about 800 cultivars (Mikki, 1998).
Pakistan ranks seventh in world dates production with an annual production of 0.557
million tons on an area of 90.10 thousand hectares, contributing 10% share in global
production (GOP, 2011). Date palm is third major fruit crop of the country having more
than 325 well known cultivars (Jamil et al., 2010). These cultivars are distinctive in their
flavor and texture and are extremely practicable for commercial production and
successful cultivation in all over the country. Sindh (50-52%) and Baluchistan (38%) are
the major date producers and contributes 85-90% share in total production of country.
While Punjab and Khyber Pakhtunkhwah (KPK) contributes 10% and 3-4%, respectively.
In Baluchistan, the prime cultivated varieties are Mozawati, Begum Jangi, Kaharba,
Sabzo, Halini, Gongna, Jansor, Dashtiari, Aseel, while in Sindh, Aseel, Fasli, Bhedir,
Karbalian, Kurpo and Red Zardi are the main focusing varieties. Hillawi, Khadrawi,
Zahidi and Dorn are grown in Punjab whereas in KPK the major cultivated varieties are
Dhakki, Mozawati, Basrai, Kango, Halini, Zahidi, Gulistan and Shakri. During the year
2010-2011, Pakistan’s dates export was $48.211 million in both fresh and dried forms.
India is the major importer of dried dates of 91.47 thousand tons while other importing
countries are Australia, Bangladesh, Canada, Denmark, Germany, Malaysia, New
Zealand, Japan, Turkey, Qatar, South Africa and United Kingdom (SBI, 2010).
Date palm has a unique significance over other fruits due to historical cultivation, multi-
nutrition, consumption and use of every plant part (Barreveld, 1993). Date fruit is highly
nutritious and an important source of sugars (glucose, fructose and sucrose), fibers,
mineral elements, vitamins, minute amount of fats and proteins (Mohamed, 2000; Al-
Farsi et al., 2005; Baloch et al., 2006). Muslims widely consume dates it in the Holy
month of ‘Ramzan’ at ‘Iftar’ time as it provides a quick source of energy. Therefore,
dates are considered as an ideal food with abundant of potential health benefits
(Barreveld, 1993; Al-Shahib et al., 2003; Al-Farsi et al., 2005; Elleuch et al., 2008).
5
Dates also contain K and little quantity of Na contents which are fit for hypertensive
individuals (Al-Hooti et al., 2002). The fruit of date palm is also considered for
antimutagenic and anticancer patients (Ishurd and Kennedy, 2005). Mostly dates are
consumed in two forms; fresh or dried. But date fruit is also consumed in different ways
like; fresh table dates, frozen dates (rutab), dates filled with nuts, chocolate coverings and
mixed with seeds of sesame seeds and numerous other such types of forms.
Climate is one of the main factor affecting dates cultivation and production. In Pakistan,
the peak production period of dates begins in hot months of July and August. Monsoon
rain during these months is a real threat for date fruit crop, because at the time of fruit
ripening, monsoon rains even for very short duration can damage up to 60% date crop
(ASF, 2010). ‘Hillawi’ and ‘Khadrawi’ are the main cultured varieties of Punjab and are
totally consumed at khalal stage. There is no concept among the date growers to process
these varieties because of monsoon rains and they harvest the fruit at khalal stage. At this
stage 50-60% fruit remains immature with poor quality and sold it at lower prices in the
market. Both these varieties are soft in texture and their ripening period starts from mid-
July to August. Monsoon rains affects these varieties badly. About 60% date fruit crop is
damaged due to these rains with uneven ripening, poor fruit quality and fruit drop. In
several cases, this harm may go up to 100% loss of the date fruit crop (SBI, 2010). Thus,
to overcome these heavy losses, there is a need to force early ripening on or even off the
tree with uniform and good quality fruit.
Fruit ripening is an irreversible phenomenon which involves different physical,
biochemical and organoleptic changes. These changes are interdependent on each other.
After successful completion of these changes fruit become edible with desirable quality
(Prasanna et al., 2007). Exogenous applications of some chemicals can accelerate the
ripening process through increased respiration, starch hydrolysis, softening, flavor and
colour. The different ripening agents such as calcium carbide, acetylene, ethylene,
propylene, ethephon (2-chloroethyl phosphonic acid), glycol and ethanol are commonly
used for the ripening of fruits and vegetables (Asif, 2012). Ethephon is potentially used to
ripen the fruit before and after harvest (Cua and Lizada, 1990; Padmini and Prabha, 1997;
Singh and Janes, 2001). Ethephon once applied, penetrates into the fruit tissues and
decomposes the ethylene as it is an ethylene generating compound. Ethylene hydrolyzes
in plant tissues and initiates the ripening in climacteric fruits (Warner and Leopold, 1967;
Cooke and Randall, 1968). Post-harvest application of various other chemicals such as
sodium hydroxide, sodium chloride and acetic acid also accelerates the fruit ripening in
6
date palm (Shamshiri and Rahemi, 1999). These have a profound effect on the maturity
and ripening by advancing or delaying the fruit harvesting period (Looney, 1998).
Moreover, heat affects the fruit ripening processes in different ways which includes
change in color (Tian et al., 1996; Cheng et al., 1988), synthesis of ethylene (Ketsa et al.,
1998), respiration (Inaba and Chachin, 1988), firmness, break down of cell wall
components (Lurie and Nussinovich, 1996) and accumulation of different volatile
compounds with enhanced fruit ripening rate (McDonald et al., 1999). Thinning is also
considered as an important managerial approach in date palm to improve the fruit size,
fruit weight, fruit quality, reduces the chances of bunch breaking, and alternate bearing
(Ibrahim and Kashif, 1998; Alkhateeb and Ali-Dinar, 2002; Ali-Dinar et al., 2002) and
also shorten fruit drop and hasten the fruit ripening (Zaid, 1999).
Modifications in the fruit maturation period and uniformity in ripening are much more
important in the date fruit industry for fulfilling the early or late market demands,
staggering fruit harvest and to avoid the effects of unfavorable climatic conditions. This
facilitates the single harvest of the fruits and also reduces the labor cost. In Pakistan,
research on date palm does not have promotes as compared to other major fruit crops
(citrus, mango and guava). Therefore, very little work has been reported regarding the
ripening acceleration and fruit quality of date palm with the use of different chemicals.
Present study, therefore, was carried out with the following objectives.
To find out the ways to accelerate the date palm fruit ripening on tree and after
harvest.
To produce uniform ripening and good quality fruit.
7
Chapter-2 REVIEW OF LITERATURE
2.1 Introduction
Date palm (Phoenix dactylifera L.) is successfully cultivated in the scorching areas of
Southwest Asia and North Africa (Dowson, 1982; Zaid, 1999; Al Farsi and Lee, 2008). It
grows well under hot, arid and brackish soil than any other fruit crops (Lunde, 1978). It is
the main fruit crop in arid and semi-arid regions of Western Asia and North Africa
situated between 24oN and 34
oN (Zaid and Arias-Jimenez, 2002). A proverb is very
famous about date palm that “its head exist in fire while its feet live in water”. It is one of
the oldest mankind‟s cultivated fruit plants on earth (Yousif et al., 1987). Due to its high
nutritious worth, yield and lengthy productive life span (100 years); it is also called as
“tree of life” in Bible (UN, 2003). The fruit of date palm has been used as staple food in
hot and desert areas of the planet for thousands of years and is considered as an admired
food product of these areas (Sarig et al., 1989). It is regarded as a one of the most
important socio-economic component of the people living in hot and dry areas of world.
As well as the civilization moves out from the Middle East, date palm cultivation has
been extended up to Spain and United States (Sauer, 1993).
2.2 Historical milieu of date palm cultivation
Historically, date palm has been linked with sustaining the human life and traditional
values of the people living in old world as a chief agricultural crop. In the universe, tree
of date palm is regarded as the oldest known tree from which man has derived benefits,
and it has been cultivated since ancient times (Riad, 2006). Initially, date palm cultivation
was coextensive to the ancient civilizations and then it widely spread from Africa
(northeast) to Tigris and uplands of Euphrates (Dawson, 1982). Pre-historically,
Phoenicians introduced the cultivation of date palm in Mediterranean areas. In Iran about
4000 years ago along the banks of two large rivers „Karoon‟ and „Karkheh‟ people have
been cultivating the dates. The exact origin of date palm has been lost in past and is still
unknown due to its long cultivation history, extensive distribution and swap of different
date cultivars, but most likely it is thought that Mesopotamia or Western India are the
original centers of date palm (Wrigley, 1995). Around 5000 years ago, the cultivation of
date palm was expanded to Arabian Peninsula, North Africa and Middle East states
(Kader and Hussein, 2009). In the Middle East the date palm cultivation was started
8
around 6000 BC (Al-Qarawi et al., 2003). Its domestication goes back to 3000 B.C. in
Mesopotamia which is now called as southern Iraq and might be its cultivation goes back
to at least 5000 B.C. in the Arab and North African countries (Zohary and Hopf, 2000). In
the Middle-East it has been cultivated as early as 6000 B.C. (Al-Qarawi et al., 2003). In
Indus Valley (Pakistan) archaeological excavations reported that the cultivation of date
palm goes back to 2000 B.C. In Arabian Peninsula, the date palm is regarded as an
ancient mankind‟s cultivated fruit plant, and played a vital role in the daily life for the
people of these areas for at least 7000 years (Ahmed et al., 1995). According to
archaeological indications, date palm has been cultivated in Mehrgarh (West Pakistan)
around 7000 BCE at the time of Neolithic civilization. This evidence of date‟s cultivation
is also related to the Indus Valley civilizations which includes Harappan period around
2600-1900 BCE (Kenoyer et al., 2005). During the second millennium B.C. date‟s
cultivation spread to Egypt and with the expansion of Islam, it has been brought to
southern Spain and Pakistan. Ancient thoughts reported that Spanish were the first who
introduce the dates in the Arabian Peninsula, North Africa, and the South Asia (Middle
East), then it reached to America (Nixon, 1951). Date palm cultivation was mainly spread
by soldiers during fighting missions, traders and excavators who eat dates as energy
source and throw away the pits there (Barreveld, 1993). Some researchers believe that it
is probably originated somewhere from the North African desert oases and southwest
Asia (El-Shibli and Korelainen, 2009). Date fruit has been considered as a rich energy
source and most popular food commodity in the Arabian Gulf and its neighboring
countries for thousands of years (Khatchadourian et al. 1982).
2.3 Significance of date palm
In world dry regions, date palm has been widely cultivated as an important cash crop and
playing an important role in the history of mankind since ancient times. It has a
significant role to nourish the residents of these areas due to its high nutritional value,
health, economic, spiritual, aesthetic and environmental importance. It also plays an
important role to provide an appropriate habitation for the nomad‟s in the form of shade
to avoid the hot winds of deserts. The fruit of date palm is composed of a fleshy seeded
pericarp (Besbes et al., 2004; Erskine et al., 2004). Worldwide, date fruit has its unique
nutritional significance and it is consumed as fresh or other derived by-products. The date
palm is a mainly an important produce in scorched areas and plays a significant part in
9
economic and social life of the people living in these areas (Besbes et al., 2004; Sahari et
al., 2007).
2.3.1 Religious and cultural significance
The date palm has religious values as well as cultural significance for mankind. In the
„Holy Qur‟an more than 20 verses narrated the importance of date palm than any other
fruit bearing plant, which is associated with the religion and Muslims. The name of date
palm is cited in the holy books like Qur‟an, Torah and Buddha, due to its prized value and
historic importance (Belarbi et al., 2000; Falade and Abbo, 2007). All the Muslims in
world eat few dates (3, 5 and 7) with few sips of water at Iftar time in the Holy month of
„Ramadan‟ to break their fast. It is important in ceremonies of Judaism, Christianity,
Islam and Hinduism. A large number of people used the date fruit in religious traditions
as a part of their food which they consumed with bread. For Muslims the religious
significance of date palm goes back to Prophet Ibrahim, who was living in Ur and loved
dates. All the Muslims in the world value the life of Muhammad (PBUH) and they try to
do as much as possible as He did. During the start of Islam, Muhammad (PBUH) eats
only dates and drink water for months. Hazrat Aisha (R.A) narrated that the Prophet
(PBUH) said: A home which has dates will never go starving (Sahee Muslim, 2002).
Hazrat Sa‟ad (R.A) narrates that the Prophet (PBUH) said, „Whoever awakens to eat
seven dates of „Ajwa‟ will not be harmed by poison or black magic (Saheeh Bukhaari,
2001). In Christianity, the palm leaves (fronds) are used for celebration of Easter festival
(Zohary and Hopf, 2000).
2.3.2 Nutritional significance
Date fruit is considered as an important nutritional component in the food of the residents
where it is cultivated. The fruit of date palm also becomes a vital part in daily life of the
people for those countries which import this fruit (El-Hadrami and El-Hadrami, 2009).
Date fruit is rich source of chemical constituents which are variable due to numerous
factors such as cultivar type, area of cultivation, climatic conditions, fertilizer application
and different management operations. (Al-Rawahi et al., 2005). Dates are rich source of
carbohydrates (70%), mostly are present in the form of sugars. Invert sugar is entirely
found in most of the date varieties, as it rapidly dissolved in the human body (Ahmed et
al., 1995; Al-Hooti et al., 1997; Myhara et al., 1999). Date fruit is considered as an
important energy component mainly due to the presence of higher sugar contents of 213
10
and 314 kcal/100g in both fresh and dried forms respectively. An adult human male and
female requires the energy with amount of 2300-2900 and 1900-2200 kcal day-1
,
respectively. Date fruit (100 g flesh) provides an approximate energy of 12 to 15% for
each adult each day. Sugars such as glucose, fructose and sucrose are the key sugars and
are the major components of the date‟s fruit being a vital and rich energy source for
human beings. Glucose plays an important role to elevate the level of blood sugars
because it is freely absorbed in digestive tract of the human body (Liu et al., 2013).
However, the presence of this amount in fresh and dried dates varies from variety to
variety, different maturation phases and climatic conditions (Barreveld, 1993). Dates are
an important constituent of dietary fibers (soluble, insoluble and total dietary), mainly
celluloses, hemicelluloses, pectin and lignin. The amount of total dietary fiber varies from
7.5 g/100 g to 8.0 g/100 g in freshly consumed and dried dates, respectively. The date
fruit comprised of 25 g per day of total dietary fibers which is enough to fulfill the
recommended daily intake (RDI) requirement of the body (Marlett et al., 2002). Hence,
dates are good source of dietary fibers in daily human beings diet.
2.3.3 Biological and curative significance
In ancient times, date fruits and seeds have been used as medication in numerous
traditional systems where date palm is cultivated (Duke, 1992; Khare, 2007). Worldwide,
dates are commonly used due to its biological significance for human beings as it contains
anti-oxidant and anti-mutagenic properties (Vayalil, 2012). According to an ethno-
medicinal survey, dates have been traditionally used for the treatment of hypertensive and
diabetics patients in southeast Morocco (Tahraoui et al., 2007). Old Egyptians used dates
as a vital tonic component in numerous aphrodisiac and different types of confectionaries.
They intake the date palm male pollens and flowers on regular basis as a source of sex
stimulants or to enhance the male fertility (Khare, 2007; Zaid, 1999). Old Hindus
consumed dried dates as medicines in their routine life to balance the body system. The
regular intake of dates is supposed to strength the body system, prevents the early hair
graying, formation of crumples and provides a lush and glossy outlook to the body skin.
The seeds of date palm fruits have been used as anti-aging tonic and to diminish the
crumples formation in women‟s skin (Bauza, 2002). The flesh of date fruits boiled in the
milk until it becomes soft and then consumed as a tonic for mothers during pregnancy as
highly nutritious food (Puri et al., 2000). Date fruits are thought to strengthen the gums in
babies having teeth problems (Zaid, 1999).
11
It is believe that intake of cooked dates with black pepper and cardamom to relief the
continuous pain in the head, dry coughs, tiredness, slight illness and loss of hunger (Zaid,
1999). Mastication of dried dates early in the morning plays a vital role to increase the
resistance power against common cold and to release the asthma (Zaid, 1999). Date fruit
is recommended for the patients of gastroenteritis, coughs, difficulty in breathing, chest
problems, illnesses, higher level of blood pressure and exhaustion (Khare, 2007; Selvam,
2008). Date fruit contains antioxidants and antimutagenic properties which gives
protection against a number of long-lasting ailments e.g. cancer and cardiovascular
illnesses (Al-Farsi et al. 2005b; Vayalil, 2012, Allaith, 2008). Date fruits are widely used
for manufacturing of drinks and alcohol as traditional medication, tonics, sex stimulants
and treatment of tumor patients (Al-Qarawi et al., 2005). Muslims have a faith that
“Person who consumes seven dates early in the morning for each day he will not be
affected by any kind of poisonous or magical effects on the day he consumed these dates”
(Miller et al., 2003). Dates are rich in insoluble fibers which minimize the danger bowl
cancer and diverticular disease (Marlett et al., 2002). Fully ripened dates contain higher
amounts of sugar contents (glucose and fructose) as compared to other fruits. These
sugars exert a number of valuable effects on the human health. Occurrence of high
amounts of fructose in dates may provide several beneficial effects on human health by
delaying or preventing the long-lasting diseases. It has been reported that minute amounts
of fructose increases the carbon flux with the help of an enzyme glycogen synthetase
which stimulates the synthesis of glycogen (Van Schaftingen and Davies, 1991; Shiota et
al., 2002; Watford, 2002).
2.4 Nutritional composition of date fruit
The fruit of date palm is an important and rich source of nutrition for humans as it
provides a large amount of sugars, salts, minerals, fibers, vitamins, phytonutrients, fatty
acids, protein and amino acids etc. Thus dates are considered as highly nutritious when
consumed with other food items (Lambiote et al., 1982) and mostly people consumed
dates in the form of fresh or dried. Vayalil (2012) widely studied that date fruit has a great
health potential as medicinal diet for the ailment of different types of human diseases.
2.4.1 Sugars composition
Carbohydrates are the main chemical components found in date fruit, mainly invert or
reducing sugars such as glucose and fructose and sucrose (non-reducing) and minute
12
amount of little concentrations of starch and cellulose (Al-Shahib and Marshall, 2003).
Based on sugar content, dates are of two types: invert sugar containing dates and sucrose
containing dates (Sawaya et al., 1983). During date fruit development and especially with
the progression of ripening, a remarkable increase in total sugars such as reducing sugars
and sucrose was noted. In date palm during the kimri, khalal and tamar fruit maturity
stages, level of TSS total sugars increased progressively depends upon the cultivars and
climatic conditions (Bacha et al., 1987). This rise in sugar composition from different
maturation stages (kimri to tamar) stage is directly linked with water contents during
these phases (Al-Shahib and Marshall, 2003). However, at hababouk stage, no soluble
sugars have been noticed (Eltayeb et al., 1999) while at kimri stage, invert sugars rapidly
increases and level of sucrose increases at khalal stage. Whereas, at rutab stage, fruit loses
its weight due to loss of moisture contents and sucrose in converted into invert sugars
(Morton, 1887; Myhara et al., 1999). During date fruit development, sugar accumulation
reached to a maximum level at tamar stage with predominant invert sugars (Morton,
1887; Bacha et al., 1987). At tamar stage, the flesh of date fruit contains highest
concentration of total soluble solids and invert sugars due to decreased water contents
(Tafti and Fooladi, 2006). Eltayeb et al. (1999) found that in some Omani date varieties,
fructose is the only sugar at kimri and khalal stages. However, during storage the fructose
concentration increased due to loss of moisture contents. In some soft and semi-dry date
cultivars, the sucrose is hydrolyzed into reducing sugars and in fully matured dates
(Mejdool and Boufgouss), no sucrose is noted, however in Deglet Noor contains the
sucrose as a dominant sugar at the time of fruit harvesting (Djerbi, 1996).
Generally, in invert sugars same trend was noticed as in total sugars (Gasim, 1994). At
rutab and tamar fruit ripening stages, maximum sugars concentration was noted due to
more photosynthetic activity and higher activity of invertase enzyme (Eltayeb et al.
1999). Soft dates contain lower level of sucrose than as compared to dry dates (Tafti and
Fooladi, 2006) and these contains glucose and fructose, excluding limited varieties which
contain sucrose (Eltayeb et al., 1999). Semi dried dates have about 50% sucrose and
invert sugars (Morton, 1987) and Eltayeb et al. (1999) reported that in semi dried dates,
higher amount of sucrose is recorded as compared to invert sugars. A date cultivar
„Deglet Nour‟ cultivated in California contains only sucrose sugar (Ensminger et al.,
1995). Date cultivars grown in Saudi Arabia comprised of about 70% invert sugars with
nearly same quantity of glucose and fructose (Tafti and Fooladi, 2006). A study carried
out in the United Arab Emirates on 12 date palm cultivars showed that level of glucose
13
and fructose increased in a rapid way as the fruit goes to developmental phases, and
moisture contents decreased during ripening and reached its lowest level at harvest
(Ahmed et al., 1995). In soft or invert sugar cultivars almost sucrose is converted into
invert sugars. Presence of plenty of sugars in date fruit have an important marketable
characteristic in both fresh intake and as processing. The presence of this huge amount of
sugars in date fruits recommends that it could be a potential source of refined sugar in
agro-industry (Samarawira, 1983).
2.4.2 Phytonutritional composition
The fruit of date palm is an important source of phytochemicals such as antioxidants,
phenolic compounds, sterols, carotenoids, anthocyanins, procyanidins, tannin and
flavonoids contents. The production or accumulation of these components depends upon
the type of fruit, harvesting stage, locality and type of soils. These phytonutrients have a
role in the nutritional and sensorial characteristics of date fruit (Abdelhak et al., 2005;
Abdul and Allaith, 2008; Al Farsi et al., 2005b; Ahmed et al., 1995; Fayadh and Al-
Showiman, 1990; Hulme, 1970). Dried dates contains contain higher amounts of these
phytonutrients as compared to other kinds of dates which represents a strong relationship
among antioxidants, phenolic compounds and flavonoids (Biglari et al., 2008).
2.4.2.1 Antioxidants composition
Dates are an important source of antioxidants especially freshly harvested dates (Al-Farsi
et al., 2007) but their ability is found in variable amounts in various cultivars and
different maturity stages that might be due to the change in phenolics. Dramatic changes
occurred in the composition of antioxidant phenolics as fruit goes to ripening phase and
this can affect the post-harvest life (Brady, 1987). Substantial quantities of efforts have
been conducted on physical and biochemical changes in date fruit during its growth and
development (Myhara et al., 1999; El Arem et al., 2011). However, very short reports are
available on the total phenolics, antioxidants (Amoros et al., 2009; Awad et al., 2011),
and tannin contents (Myhara et al., 2000) of dates during different maturation phases. The
hydrophilic activity of antioxidants is higher which is interrelated to phenolics, but the
activity of lipophilic antioxidants is very low with no changes during the fruit
development (Amorós et al., 2009). Overall, date fruit is regarded as rich source of
natural antioxidants having antiradical activities.
14
2.4.2.2 Phenolics composition
The total phenolics in date fruits are found in variable amounts which depend upon the
cultivars and extraction methods that create unacceptable assessment quantitatively. At
early fruit maturity stages phenolics are present in higher amount than later stages
(Biglari et al., 2008). Drying is considered as un-favorable as there are chances of
oxidative breakdown either through enzymes or degradation of phenolics due to heat
(Shahidi and Naczk, 2004). Though, the increase in phenolics were observed in few
cultivars after drying due to the tannins degradation by heat and different ripening
enzymes which involves during whole the dehydrating procedure, which release phenolic
compounds and break the linkage between p-coumaric acid and lignin and between
ferulic acid and arabinoxylans due to high temperature (Maillard and Berset, 1995). It has
been reported that in fresh and dried dates of Fard date palm cultivar, phenolics
efficiently increased because of tannins degradation and maturation of degradative
enzymes at high temperature (Al Farsi et al., 2005b).
2.4.2.3 Flavonoids composition
In plants, flavonoids are present in abundance amounts and hold a lot of beneficial effects
on health such as antioxidants and radical scavenging activities. Flavonoids present in
plants possess diverse health benefits, which includes antioxidant and radical scavenging
activities, to relieve some long-lasting illnesses, decreased the heart problems and
different types of tumors (Tapas et al., 2008). Hong et al. (2006) measured the thirteen
different types of flavonoids in „Deglet Noor‟ cultivar at khalal phase. Now a days date
fruits have a unique significance due to the presence of huge amounts of flavonoid
sulfates in the food (Hong et al., 2006). Chaira et al. (2009) reported that Tunisian date
cultivars „Korkobbi‟ contain higher amounts of flavonoids contents.
2.4.2.4 Polyphenols composition
Polyphenols are also an important constituent found in date fruit and making up to 3% of
the date flesh on dry weight basis (Hashempoor, 1999). The principle role of these
polyphenols is to convert the astringent taste of the fruit into tasteless form mainly due to
the reaction with protein (Hashempoor, 1999). The concentration of astringency in fruits
at different maturation phases depends upon the intensity of tannin contents, lesser the
level of tannin contents fruits were less astringent (Myhara et al., 2000). The level of
tannin contents is recorded more at immature green kimri stage (Messaïtfa, 2008) but its
15
concentration decreased rapidly as the fruit enters into mature khalal phase (Mohamed,
2000; Messaïtfa, 2008) and gradually decreased at rutab ripening phase (El-Agamy et al.,
2001) and fastly declines at last stage of maturity (tamar) and reached to a lesser level
(Bacha et al., 1987). Tannins in date fruits play a double role in taste observation and
helps in the color development during the ripening and storage (Hashempoor, 1999). As
well as the date fruit drops from its greenish color and fruit turns into reddish or yellowish
color, tannin contents are stored in cells and convert into unsolvable components. In dates
a thin coating of tannins is present at immature green kimri stage under the fruit skin
which makes the fruit astringent in taste. Booij et al., (1992) reported that a significant
decrease in tannin contents occurs as the fruit proceeded from immature kimri stage to
mature khalal to rutab and finally tamar stage in „Deglet Noor‟ cultivar. In dates, mostly
blackening occurs after harvesting due to the presence of tannin contents (Hashempoor,
1999).
2.5 Activities of enzymes during date fruit maturation
In date palm the most important enzymes found at different fruit maturation phases are
invertase, polygalacturonase (PG), pectin methyl esterase (PME), cellulase, and
polyphenol oxidase (Rohani, 1988; Fallahi, 1996). Invertase is the most active enzyme
found at rutab stage of fruit maturation (Al-Kahtani et al., 1998). Mostly in soft date
cultivars the activity of invertase is high and it is the most affecting date‟s fruit quality
enzyme. It is considered as the most responsible enzyme for the accumulation of invert
sugars at tamer phase of fruit maturity (Vandercook et al., 1980). The activity of invertase
noted higher at later fruit developmental stages (Zare et al., 2002). In soft date cultivars,
invertase hydrolyzed the sucrose into glucose and fructose but to some extent in semi-dry
and dry date cultivars (Biglari, 2009). Dried date cultivars contains little or no invertase
enzyme whereas, a small quantity of this enzyme if found in semi-dried dates as
compared to soft dates cultivars have maximum level of invertase (Hui, 2006; Eltayeb et
al., 1999). Invertase enzyme in date fruit is sensitive to high temperature and storage
duration (Zare et al., 2002). During date fruit ripening, there is conversion of protopectin
into water soluble pectin through the combination of PG and PME (Biglari, 2009, Al-
Jasim and Al-Delaimy, 1972). At kimri stage PG is not present but it progressively rises
as well as fruit goes to maturity (Mustafa et al., 2006). The higher activity of PG enzyme
found at later red or yellow fruit developmental stage and soft date cultivars showed
higher level of this PG activity (Hasegawa et al., 1969). In date fruit a adjacent
16
correlation found among the PG activity and fruit softening throughout ripening
(Hasegawa et al., 1969; Eltayeb et al., 1999). The activity of PG is found maximum in
soft dates (Hui, 2006). As the fruit goes to khalal and rutab fruit maturity stages, PME
activity increases (Biglari, 2009) which are mainly due to loss of pectin content (Al-
Shahib and Marshall, 2003). The activity of cellulase rises as the date fruit matures (Hui,
2006). At kimri phase cellulase is absent and its activity rises as the fruit goes to maturity,
reaching its highest level at final rutab phase while it remains constant at tamar phase of
fruit development (Hasegawa and Smolensky, 1971). Fruit softening in dates is mainly
occurred due to the breakdown of cellulase to cellulose into more soluble constituents,
ultimately glucose with decreased fiber contents (Biglari, 2009). The polyphenol oxidase
is the enzyme which is mainly involved to break down the tannins. The activity of
polyphenol oxidase remains higher at kimri stage than khalal and tamar date fruit
maturation phases (Hui, 2006). The natural brown color of all date fruit might be due to
the activity of polyphenol oxidase by oxidation of polyphenols (Al-Qarni, 2005).
2.6 Fruit classification on the basis of ripening
Harvesting of fruits should be practiced at their accurate physiological maturity and status
of ripeness (Harman and Patterson, 1984). Fruits are classified into two classes depends
on the respiration pattern and production of ethylene; as climacteric and non-climacteric
fruits.
2.6.1 Climacteric fruits
These types of fruits can be ripened of after harvest at proper physiological maturity. At
maturity both the respiration and ethylene generation however negligible at ripeness,
increased drastically as the fruit ripening progressed just at the start but it further declines
(Gamage and Rehman, 1999). Ripening is escorted by a piercing rise in respiration and
ethylene generation in such type of fruits. Ethylene production at during fruit ripening is
supposed to regularize the entrance of several genetic factors associated with ripening
which are liable for ethylene synthesis, break down of cell wall components, loss of green
pigments, carotenoids formation, and transformation of starch into sugar (Gray et al.,
1992; Theologis, 1993; Alexander and Grierson, 2002). The date palm is a climacteric
fruit because the respiration rate is more during fruit growth which preceded the higher
ethylene production and then it decreases as the fruit goes to maturation phase but again a
rise in ethylene production occurs as fruits goes to ripening stage (Abdel-Latif, 1988).
17
2.6.2 Non-climacteric fruits
Such kinds of fruits are not accomplished their ripening progression, when they are
removed from the mother plant. At this stage a little amount of ethylene is produced in
fruits which do not give any response after the application of exogenous ethylene
production. Such fruits show relatively slow decline in the respiration rate and ethylene
formation, during progression of ripening (Gamage and Rehman, 1999). These fruit do
not demonstrate any significant change in their respiration rate and production of ethylene
which persists at a minor degree. Nevertheless, in certain plant species, various features
of ripening, such as loss of green pigments and fruit softening occurs in fruits due to the
accumulation of precise ethylene level (Goldschmidt et al., 1993; Wills and Kim, 1995).
2.7 Fruit ripening mechanism
Ripening involves a number of physiological and biochemical alterations after the
maturation in fruits. It can be defined as variations that "happen since the final phases of
progression and expansion over the initial phases of senescence and outcome in
distinguishing aesthetic and/or food value" (Watada et al., 1984). A varied range of
biochemical variations occur in fruits during ripening such as increased rate of
respiration, loss of green pigments, carotenoids formation, anthocyanin and improved
action of cell wall loosening enzymes (Brady, 1987). During ripening the loss in color is
mainly due to the degradation of chlorophyll and disassembling of photosynthetic
mechanism and creation of numerous forms of anthocyanin and their buildup in vacuoles
(Tucker and Grierson, 1987; Lizada, 1993). Fruit flavor enhancement is owing to an
overall rise in sugariness that is due to enlarged gluconeogenesis, polysaccharides
hydrolysis, chiefly starch, reduced acidity, and build-up of sugars and organic acids
(Grierson et al., 1981; Lizada, 1993). In fruit, firmness is mainly linked with
disassembling of the cell wall (Seymour and Gross, 1996) and alterations in the level of
pectin are certain understandable variations in the fruit outer layer during ripening
(Marin-Rodriguez et al., 2002). Various types of enzymes such as PE, PG and PL plays
an important role during the fruit softening and solubilization of pectin and starch
hydrolysis (White, 2002) and starch hydrolysis.
2.8 Date fruit maturation and development
The date fruit ripening is a complex phenomenon which involves the breakdown of
chlorophyll, carotenoids formation, degradation of cell wall and transformation of starch
18
into sugars (Eltayeb et al., 1999). Date palm plant bears fruit only once a year as its fruit
development or maturation period is very length and it takes about 6-7 months. A large
number of physiological and biochemical changes occur during all these maturation
stages. During the fruit formation and ripening date fruit passes through five different
phases i.e. Hababouk (baby fruit), Kimri (immature fruit), Khalal (full colored mature
fruit), Rutab (soft brown) and Tamar (hard raisin like appearance) and these are common
Arabic terms but also accepted in English languages (Fayadh and Al- Showiman, 1990;
Al-Shahib and Marshall, 2003; Fadel et al., 2006).
2.8.1 Hababouk stage
It is the earliest stage of fruit development which starts after fertilization and it lasts for 4
to 5 weeks by the loss of two unfertilized carpals (Eltayeb et al., 1999). The fruits are
immature and also called as‟ baby fruit‟ which turns into calyx (fruit cap). At this stage
the fruit is just like a pea sized, round, creamy to faint green in color and weighs up to a
gram by holding the moisture content of 85 to 90% (Al Noimi and Al-Amir, 1980;
Ahmed et al., 1995; Al-Shahib and Marshall, 2003; Fadel et al., 2006).
2.8.2 Kimri stage
It is the longest stage (period) of date fruit development and it appears in first 17 weeks
after fertilization (Morton, 1887) depending upon location and cultivar. The fruit at this
stage remains immature young, elongated (Eltayeb et al., 1999) and hard surface with
greenish color (Hui, 2006). In this phase fruit weight increases and tannin concentration
reached at maximum level (Eltayeb et al., 1999). It is categorized into two stages. In first
stage, fruit size and weight rapidly increases with more sugars accumulation and water
contents. While in seconds phase, reduction in fruit size, weight, acidity and sugars
occurs with higher water contents as compared to first stage (Fallahi, 1996; Hashempoor,
1999; Najeh et al., 1999; Al-Shahib and Marshall, 2003).
2.8.3 Khalal stage
This stage starts next 6 weeks to kimri phase (Morton, 1987) in which the fruit gains its
maximum size and weight, turns into yellowish or reddish color depends upon the variety
and surface is hard (Hui, 2006). At this stage fruit volume, sugars, acidity and water
contents continuously decrease. Sugars accumulation gradually increases and this phase
takes about 5 weeks for completion depends on the cultivars (Eltayeb et al., 1999). In this
19
fruit maturation stage, mostly fruit is consumed in raw or fresh form or used for making
of jams and date syrup (Hui, 2006).
2.8.4 Rutab stage
This stage remains 4 weeks (Morton, 1987) after khalal stage and fruit loses water
contents (Al-shahib and Marshall, 2003). At this stage, fruit starts ripening from the point
of apex and fruit becomes firmer, sweet in taste with dark brown appearance, lower
astringency, and sucrose transforms into glucose and fructose (Morton, 1987). Fruit starts
to lose weight due to consistent loss of water contents (35-40%). The concentrations of
total sugars and SSC were increased and sucrose is converted into reducing sugars with
minimum intensity of tannin contents (Al-Hooti et al., 1995; Ahmed et al., 1995; Fadel et
al., 2006) and this phase is the beginning of fruit ripening (Najeh et al., 1999). Fruits of
this stage are mainly consumed as jams, date bars paste etc. In some cultivars the fruit at
this stage is mostly eaten as fresh rutab dates which are highly nutritious and full of
energy (Hui, 2006).
2.8.5 Tamar stage
This is the last phase of date fruit ripening and it takes about two weeks depends on the
variety (Morton, 1987). At this stage, fruit attains higher amounts of SSC, sweeter, less
astringent, and softer and color turns into darkish brown with presence of furrows on the
outer surface (Hui, 2006). At this phase, glucose and fructose are present in abundance
while sucrose is lacking (Al-Hooti et al., 1997; Myhara et al., 1999). Fruits of this stage
loses higher amount of water for with accumulation of more sugars which plays an
important role for the prevention of fermentation (Najeh et al., 1999). In dried varieties,
the fruit of tamar stage becomes light colored with hard surface as compared to soft date
varieties (Fallahi, 1996). The fruit of this stage is almost used for storage purpose due to
presence of lower water contents and higher amounts of sugars (Hong et al., 2006; Awad,
2007). These dates can be used for storage up to one year under ambient conditions if
firmly pressed (Najeh et al., 1999).
20
Khalal stage (cv. Khadrawi)
Rutab stage (cv. Khadrawi)
Tamar stage (cv. Khadrawi)
Slide-2.1: Different edible stages of Khadrawi fruit
21
Khalal stage (cv. Hillawi)
Rutab stage (cv. Hillawi)
Tamar stage (cv. Hillawi)
Slide-2.2: Different edible stages of Hillawi fruit
22
2.9 Monsoon rains and dates industry
Date palm industry is highly affected due to the occurrence of monsoon rains at the time
of fruit harvesting and ripening which starts from July to August. Mostly the dates are
harvested during these months at different maturity stages according the customer
demands. Most of the growers harvest the dates at mature khalal or early rutab stage and
process them into dried dates (Khajoor) after adopting hydration or de-hydration
techniques to fulfill the market demands. The occurrence of rains during this period is
very harmful especially for the fruits which were going to be harvest. Experts say that
these rains destroy up to 60% of dates and in few cases this harm may go to 100%
damage of the dates. This threatening situation is not bearable for the poor date growers
as they wish to earn some money for their living after a long span of field work. This
condition becomes further worsens when the poor growers do not save a little part of their
crop from full flourishing fruit crop (SBI, 2011). Date palm growers mostly convert the
dates in full dried form (Chohara) with less economic value by harvesting the fruit at
early maturity stage (un-ripened) to avoid the risk of monsoon rains. Similarly they adopt
old drying techniques which decreased the quality of the produces under unhygienic
conditions which harshly affects their profit. Processing of dates through such ways or
means contributes about 20 to 30% post-harvest losses every year (ASF, 2010).
2.10 Fruit ripening agents
The ripening agents probably disturb the epidermal cells and protoplasm, thus liberating
and triggering the activity of enzymes. Ripening by contribution of enzymes different
enzymes such as invertase, polygalacturonase (PG), cellulase, polyethylene (PE) and
peroxidase (PO), causes alterations in the structural parts e.g. pectin and cellulose that
grasp the cells organized, to become soluble, and tannin contents precipitates. Hence, it
facilitates the ripening process of fruits from khalal to tamar, which involve; precipitating
out of tannins, increasing small sugars causing sweetness, texture softening, color
changes and other ripening related quality compositional characters. This degree of
modification is variable depends upon the fruit maturation phase and lot of others
environmental factors which are liable for the ripening and or curing of date fruits
(Shamshiri and Rahemi, 1999).
23
2.10.1 Ethephon (2-chloroethyl-phosphonic acid)
The fruit ripening hormone ethylene is released by ethephon which is hydrolyzed in plant
tissues and initiates the ripening in climacteric fruits, is now commercially used in various
fruit species (Cooke and Randall, 1968; Warner and Leopold, 1967). The main reaction
which is generated by the ethephon is to breakdown the ethylene (Anderson, 1968).
Ethephon is now being widely used in agriculture sector for the promotion of flowering,
defoliation, and fruit ripening and so on. Ethephon applications had to be accompanied
with severe pruning in order to be able to enhance ripening of Samany dates (Hussein et
al., 1993). Thus, many researchers have been attempting to accelerate ripening of dates
after harvest (Khalifa et al., 1975; Rouhani and Bassiri, 1977). It was found that due to
the hydrophilic nature of ethephon, its diffusion across the cuticle is very slow (Farag,
1989) and its penetration across the cuticle could be enhanced by changing its
formulation (Farag and Palta, 1992). Application of ethephon in newly emerging fruits
and leaves increased the level of ethylene in two days. In most of the fruit crops ethephon
plays a vital role to enhance the chlorophyll degradation and carotenoids formation
(Sonkar and Ladaniya, 1999; Drake et al., 2006). The effectiveness of ethephon depends
upon its rate (Sims et al., 1970; Knavel and Kemp, 1973), time (Hoyer, 1996),
formulation (Conrad and Sundstorm, 1987), fruit maturation phase (Beaudry and Kays,
1988; Hoyer, 1996; Kahn et al., 1997), and environmental features (Beaudry and Kays,
1988). Ethephon hasten and liberate the fruit maturation cycle in pepper fruits as a
ripening agent (Sims et al., 1970; Batal and Granberry, 1982). Fruit maturity is the key
factor which affects the ethephon efficacy during the ripening of pepper fruit (Batal and
Granberry, 1982; Armitage, 1989). Furthermore, initial application of ethephon after fruit
set resulted in a significant yield reduction (Mougheith and Hassaballa, 1979). The
application of ethephon is known to increase total soluble solids contents (Khalifa et al.,
1975; Rouhani and Bassiri, 1977). Application of ethephon before and after harvest
mostly causes the changes in skin color however; some internal compositional changes
have also been reported such as TSS, sugars, and juice contents increased (Mazumdar and
Bhatt, 1976) while loss of green pigments, level of acidity, and vitamin-C contents
decreased during degreening (Ramana et al., 1973; Singh et al., 1978).
2.10.1.1 Pre-harvest ethephon application
Pre-harvest ethephon application with different concentrations gives irregular results
regarding the color development and defoliation which linked to each other (Stewart,
24
1977). Pre-harvest ethephon hasten the fruit maturity time in apples (Edgerton and
Blanpied, 1970). According to Kamal (1995) revealed that fruit ripening enhanced about
one month by foliar application of ethephon in „Zaghloul‟ and „Samani‟ date palm
cultivars. The significant increase in rutab fruit yield per bunch was noted in date palm
cv. Hilali by pre-harvest application of ethephon either it sprayed or injected two weeks
from fruit color turning phase as compared to untreated fruits (Awad, 2007). Fruit
ripening accelerates by about one month with application of ethephon @ 1500 ppm in
„Zaghloul‟ and „Samani‟ date cultivars soon after complete blooming (Kamal, 1995).
Musa (2001) revealed that by injecting ethephon @ 2 ml/bunch in „Mishrigi Wad Khatib‟
and „Mishrigi Wad Lagi‟ cultivars fruit ripening time accelerates two to three folds than
fruits those were sprayed with ethephon @ 1000 ppm.
Pre-harvest application of ethephon also accelerates the fruit maturation time in other fruit
crops. In rabbiteye blueberry the application of ethephon promotes the fruit ripening,
however the stimulatory action of ethephon on the ripening of fruits was dissimilar
regarding the fruit grade and ripening properties (Ban et al., 2007). Similarly, in apple
and cranberry the influence of ethephon has been well known for the improvement of skin
color (Murphey and Dilley, 1988). In Satsuma the fruit ripening accelerates by fifteen to
twenty days with uniform and thin peel and superior bio-chemical composition by the
application of ethephon before the onset of yellow fruit stage (Nodiya and Mikaberidze,
1991). In Beladi oranges the application of ethephon two times before fruit colour break,
improved the chlorophyll breakdown and increases the production of carotenoids (Al-
Mughrabi et al., 1989). The commercial application of ethephon is done two to three
weeks in „Delicious‟ apples before harvest to increase the fruit color development and
obtain early maturity (Hammett, 1976). It has been shown that ethephon accelerates the
physiological process of fruit maturation by promoting the ethylene production in blue
berry plants (Lieberman, 1979). Prohens et al. (1999) reported that ethephon spraying @
500 mg/L improves the earliness and fruit quality without any significant effect on yield
in the hybrid clones of pepino (Solanum muricatum Aiton). In „Delicious‟ apples the
application of ethephon at early fruit maturation phases accelerates the fruit ripening to
breakdown the cell wall and soften the fruit tissues (Curry, 1994). Bal et al. (1996)
reported that pre-harvest application of ethephon @ 400 ppm hasten the fruit ripening
period of ber (Zizyphus mauritiana Lamk.) by about two weeks. In Figs, pre-harvest
ethephon application (at the end of slow growth period ), when most of the basal figs
showed color break, stimulated the growth and shortened the maturity period of fruits
25
without any adverse effect on fruit quality. The fruits those were treated started to ripen 5
days earlier than untreated ones, and most of the fruits were harvested when control fruits
had just started to mature (Çelikel et al., 1997). Kim et al. (2004) elucidated the effect of
ethephon on fruit quality and maturity of astringent persimmon cv. Tone Wase and
reported that ethephon accelerates the fruit maturity by 13 to 22 days when sprayed 120
days after bloom. According to Yuzo and Tomoya (2002) that ethephon application 140
days after full bloom in 'la France' accelerated the harvesting time by about 5-10 days.
Ross (1993) revealed that ethephon at 1000 to 1500 mgL-1
significantly increased the fruit
soluble solids concentration and substantially reduced the fruit starch when applied 12 to
26 days after full bloom in apple (Malus domestia Borkh., spur „Delicious‟ strains). Pre-
harvest application of ethephon was found to enhance the ripening processes and
noticeably increased the total soluble solids (Mougheith and Hassaballa, 1979). Pre-
harvest ethephon application was also found to improve the fruit quality composition
(Maximos et al., 1980), SSC, sugars, and juice percentage increased (Mazumdar and
Bhatt, 1976) while degradation of chlorophyll and level of acidity and vitamin-C contents
lower down during degreening (Ramana et al., 1973; Singh et al., 1978). Juice percentage
and total soluble solid remained higher in fruits those were sprayed with ethephon before
harvesting (Chauhan and Rana, 1974; Soni and Ameta, 1983).
2.10.1.2 Postharvest application of ethephon
Most of the citrus species i.e. oranges, tangerine, grapefruit, and lemon when dipped in
the solutions of ethephon for a few seconds to quite a few minutes gave attractive colour
within 7-10 days after application (Fuch and Cohen, 1969; Yong et al., 1970). In Meiwa
kumquat fruits the orange red fruit colour developed by the application of ethephon (400
ppm) and a rapid increase in color development was recorded in treated fruits than non-
treated fruits which were stored at 10oC. The application of ethephon at the rate of 5%
increased the average fruit weight and peel/fruit and juice/fruit ratio by reducing the
acidity without affecting the sugar composition (Hashinaga and Itoo, 1985). Dipping of
mango fruits in ethephon @ 1000-2000 mgL-1
for 1 to 2 min accelerates the ripening with
acceptable product quality (Sergent et al., 1993). Fresh market pineapples (Ananas
comosus L.) treated with ethephon produced uniform full yellow color 2-3 days earlier
than untreated ones with superior eating quality (Smith, 1991). In „Coorg‟ mandarins
color was improved by ethephon dipping @ 1000 ppm (Ramana et al., 1973). In Green
Valencia and Mosambi sweet oranges, yellow color appeared in 5-7 days when fruits
26
were dipped in ethephon @ 1000-2000 ppm under ambient conditions (Arora et al., 1973;
Chauhan and Parmar, 1981; Purandhare et al., 1992). Treatment of Mosambi oranges
with ethephon dipping @ 3000 ppm showed superior bright yellowish color in short time
(Sanghvi and Patil, 1983).
2.10.2 Application of NaCl and acetic acid
Acetic acid is a universal metabolic agent and occurs in plants and animals. It is a plant
bio-regulating agent which belongs to auxin group and plays a crucial role for some
particular physiological processes within the plant body. These bio-regulators can speed
up or slow down the growth or maturity rate or otherwise change the plants action or their
products (Lemaux, 1999; Olaiya and Osonubi, 2009). In date palm fruit ripening with salt
and acetic acid is insufficient and only a few evidences are reported which are variety
specific (Kalra et al., 1977; Asif and Al Taher, 1983). Saleem et al. (2005) reported that
NaCl (2%) is more effective to accelerate the fruit ripening in „Dhakki‟ date palm cultivar
with good quality fruits as compared to untreated fruits. It has been reported that CaCl2
plays an important role to reduce the post-harvest problems and improved the produce
quality during the ripening (Stanly et al., 1995). Furthermore, it improves the strength
ability of fruit skin and makes the cell wall and tissues more resistant against different
types of infections (Mignani et al., 1995; Hong et al., 1999). It has been documented that
by increasing the salt concentration, ripening increased progressively in Khadrawi and
Shamran cultivars while by adding acetic acid showed greater effect (Kalra et al., 1977).
Sodium chloride (3-6 gL-1
) significantly increased the fruit ripening characters such as
color, flavor, and production of ethylene and rate of carbon dioxide production.
Farahnaky and Afshari-Jouybari (2011) conducted a study on „Mazafati‟ date cultivar by
incubating the fruits in hot solution of acetic acid 0.5% at 40 ± 1oC for 72 h. They
reported that the treated fruits contain more TSS and acidity than control fruits. Great
losses of fruit softness were recorded for the duration of 12 h incubation and were
acceptable to the customers in terms of organoleptic properties. The applications of NaCl
and acetic acid alone or in combination significantly enhance the total soluble solids;
reduced the water contents and fruit firmness. Acetic acid (2%) showed superior effect on
fruit ripening than NaCl; however the fruits treated with NaCl were better in appearance
(Shamshiri and Rahemi, 1999). Farahnaky et al., (2009) indicated that during ripening of
„Kabkab‟ dates with NaCl and acetic acid, the moisture content and colour changed
significantly. The major change was observed for firmness where a maximum force for
27
puncture test varied from about 1000 to 50 g force for all samples after 72 h of incubation
at 40°C. Harvesting at khalal stage followed by treating the fruits with NaCl and/or acetic
acid solutions and an incubation stage at 40°C showed to be a promising method for
accelerating the ripening of „Kabkab‟ dates from khalal to tamar stage. Tafti and Fooladi
(2004) postulated that treatment of „Mozafati‟ fruits at the end of khalal stage with acetic
acid (4%) and placing them in a maturation room at 38-40oC with 70-80% relative
humidity for 3-5 days is the effective and economical method for artificial ripening of the
fruits. Chatha et al. (1985) reported that best curing of „Khadrawi‟ dates harvested at
khalal stage was performed in the solution of acetic acid at 0.09% + NaCl at 1.5%. Haq
(1990) treated the „Zahidi‟ dates for curing with acetic acid and NaCl alone or in
combination. He concluded that combined application of acetic acid (2.5%) + NaCl
(12%) showed significantly superior results by affecting the early ripening of the fruit and
make the fruit soft over all other treatments. Another study conducted by Mirza and
Meraj-ud-Din (1988) by treating the fruits of „Dhakki‟ and „Basra‟ cultivars at khalal
stage with 3% brine solution, 0.25% acetic acid and 0.25% citric acid solution for 5
minutes. Their results indicated that different chemical treatments enhanced the fruit
ripening process significantly with better fruit quality.
2.11 Hot water applications
Fruit and vegetables can be treated with heat by means of hot water dipping, vapor, or hot
dry air. Recently, extensive global concern in the heat treatment for maintaining the food
quality and diseases has been shown in many of the literatures. Water is the most efficient
and preferred medium in many of the applications than the others. Hot water treatments
have a number of benefits such as: comparatively simple in use, short time exposure,
consistent handling of fruits and temperature of water and burning of disease causing
agents with economic advantage as it is cheap as compared to other heat application
methods (Fallik et al., 1999; Garcia-Jimenez et al., 2004). Higher temperature exposure
in agricultural products alters the various physiological processes such as heat shock
proteins transcripts and different level of proteins in such type of products (Lurie, 1998).
Presently, hot water treatments in fruits and vegetable have got the extensive worldwide
attention for the maintenance of product quality and to control various types of diseases.
Higher temperature increased the intensity of heat shock proteins in exposed agricultural
products (Lurie, 1998). Moreover, heat affects a number fruit ripening processes which
includes the color (Cheng et al, 1988; Tian et al., 1996), ethylene production (Ketsa et
28
al., 1999), rate of respiration (Inaba and Chachin, 1988), firmness of fruits, breakdown of
cell wall (Lurie and Nussinovich, 1996) and formation of different volatile compounds
(McDonald et al, 1999). All the agricultural products showed a variable response to heat
treatments. Inappropriate application of heat to agricultural commodities can cause
ripening progression or heat damage (McDonald et al., 1999). Heat treatment triggered by
significantly increasing the rate of respiration and production of certain types of organic
acids (Lurie and Klein, 1990). The harshness of heat contact regulates the thermo
tolerance reaction of treated produce which depends upon the exposure temperature
(Lurie, 1998).
Hot water is an efficient means of heat transfer and it maintained the uniform
temperature within a short time limit (Couey, 1989). Hot water has been widely adopted
as heat disinfestation due to its effectiveness and more economic (Jacobi et al., 1995).
Heat treatments increased the thermal tolerance in exposed produce against various
environmental features such as time of application, duration and application type. These
can alter the fruit ripening by hindering, promoting and or disturbing all the processes
involved during the fruit ripening. In mango fruits, heat treatments accelerates the yellow
color and uniformity of the fruit skin, however fruit becomes softer in a number of
varieties (Jacobi et al., 2001). The concrete mechanism by which heat treatments
accelerates the ripening in mango fruits is still unknown. Post-harvest heat application in
fruits and vegetables plays a wide role to overcome the problems of diseases and insects
(Lurie, 1998). In banana fruits, hot water treatments stimulated the antioxidants activities
due to increase in phytochemicals and decreases of ethylene during the progression of
ripening which cause delay in banana fruit ripening processes (Nittaya et al., 2011). Hot
water treatments significantly affected the rate of respiration, C2H2 production and
activities of different ripening enzymes (aminocyclopropane carboxylic acid) in fruits
during ripening Marrero and Paull (1998). The exposure time of hot water treatments is
more effective as compared to the temperature of hot water during the ripening of banana
fruits Wall (2004). Higher temperature for long exposure significantly reduced the
conversion process of starch into sugars without any significant effect of total soluble
solids and acidity level. Bananas exposed at 51oC for 20 minutes had delayed respiratory
peaks and ethylene production. Mild peel injury was observed on fruits exposed to higher
temperatures (49-51oC) for longer durations (15-20 minutes).
Shahnawaz et al. (2012) reported that mango fruit treated in HW ripened earlier under
ambient conditions (38 ± 4oC) as compared to fruits those were untreated. These early
29
ripened mango fruits received higher organoleptic scores in terms of color, firmness,
taste, texture and aroma. Hot water treatments significantly increased the level of acidity
in ripened mango fruit under ambient conditions than untreated fruit. This rise may be
due to the degradation of bio-chemical constituents of the un-ripened fruits during
respiration, resulting in certain acids (Anwar and Malik, 2007). In another study HWT at
55oC and 45
oC has reduced the vitamin C content of mango as compared to control. This
attributed to susceptibility of ascorbic acid to oxidative destructions particularly slow in
hot water treatment as compared to ambient temperature. These findings were also
confirmed by Pudmini and Prabha (1997) and Thomas and Oke (1980) claimed that the
reduction of vitamin C during fruit ripening. Furthermore, total soluble solids of mango
fruit was significantly affected by hot water treatments. They reported that the increase in
total soluble solids might be due to the alteration in the cell wall structure and break down
of complex carbohydrates into simple sugar and this hydrolytic changes in starch is may
be due to hot water treatment whereas slow changes in TSS was also observed in control
samples. There was a gradual increase of total sugars in mangoes treated with hot water
treatment at 55oC and stored at room temperature as compared to 45
oC and control stored
at room temperature. The increase in total sugar level could be attributed mainly due to
breakdown of starch into simple sugars during ripening along with a proportional increase
in total sugars which was attributed to the increased activity of amylase and other
enzymes converted into sucrose, glucose and fructose during storage (Aina, 1990;
Rajwana et al., 2010). Increase in non-reducing sugar by HWT may be due to acidity by
physiological changes during storage (Anwar and Malik, 2007). Jabbar et al. (2011)
found that when fruits were given hot water treatment, reducing sugar remained higher
than non-reducing sugar throughout ripening process under ambient temperature. Carillo
et al. (2000) and Malik et al. (2003) reported that fruit pulp color turned into pale yellow
due to hot water treatment that increased enzymatic oxidation and photo discretion as
compared to control. Warm water at 45oC for 30 minutes increases the soluble solids
concentrate (SSC), weight loss, enhanced the fruit firmness, reducing the decay,
prolonging the shelf life and improving some quality characteristics in tomato fruit (El-
Assi, 2004). In date palm the hot water dipping temperature for artificial ripening of soft
date varieties ranges from 60-65oC (Kader and Hussein, 2009).
2.12 Application of thinning practices
In date palm, fruit thinning is a very critical managerial operation which effects the
development of fruits, gives early maturity, larger fruit size; regulate the tree yearly
30
bearing and better quality fruits by reducing the competition among the remaining fruits.
Fruit thinning is one of the main principles of commercial date production. Usually fruit
thinning is carried out physically or by using different chemicals. However, to avoid the
risk of various environmental issues or health hazards, thinning is considered as an
effective managerial approach for getting the desired quality traits.
Several methods have been used to thin the date palm trees such as bunch thinning,
strands thinning and single fruit removal thinning (Ali-Dinar et al., 2002). Combination
of single fruit removal and strands thinning had substantially improved the fruit quality in
„Medjool‟ date cultivar (Osman and Abdulrida, 1989). Thinning by progressive removal
of strands improves the physical and chemical parameters while overall yield was reduced
in „Sewi‟ date cultivar (Moustafa, 1993). The methods of thinning used in these
experiments included removal of part of the length of the strands (Tavakkoli et al., 1994;
Samavi, 1998; Sayyahpoor, 2002); removal of some of the entire central strands
(Tavakkoli et al., 1994); removal of some of the fruit on the strand (Tavakkoli et al.,
1994); and removal of some of the bunches (Davoodian, 1999). Removal of fruit bunches
at the intensity of 10 to 30% significantly increased the yield per bunch than fruits those
were untreated (Akl et al., 2004; El-Assar, 2005 and Alwasfy and Mostafa, 2008).
Removal of 30% strands from the center of the bunch resulted in better yield, accelerates
the ripening and produces superior quality fruit as compared to fruit without thinning in
„Shamran‟ and „Nabetet ali‟ (Godara et al., 1990; Al-Ghamdi et al., 1993). In „Zaghloul‟
date palm cultivar, shortening of strands or by reducing their number 2-4 weeks after
pollination positively increased the total soluble solids and sugars with optimum fruit
yield than un-thinned fruits (Khalifa et al., 1987; Abdel-Hamid, 2000; Hammam et al.,
2002; Bassal and El-Deeb, 2002; Marzouk et al., 2007 and Al-Wasfy and Mostafa, 2008).
Bloom thinning improved the fruit quality compositional parameters by regulating the
yield in „Zaghloul‟, „Haiany‟, „Seewy‟ and „Amry‟ date palm cultivars.
Removal of central strands four weeks after pollination led to optimum fruit quality in the
„Succary‟ date palm cultivar (Soliman and Harhash, 2012). Al-Obeed et al. (2005) on
„Succary‟ dates found that the shortening of strands by 40% gave the highest value of
total sugars. Bunch thinning significantly increased the fruit physical and biochemical
characteristics of tamar stage fruits in „Khalas‟ date cultivar (Soliman et al., 2011). Al-
Darwish (2010) found that fruit thinning reduces the fruit shrivel percentage and
improved the quality. Similarly fruit thinning increases the fruit size, accelerates the fruit
ripening, and minimizes the fruit drop and alternate bearing, one of the main principles of
31
commercial date‟s production. It increases fruit size and quality, reduces alternate bearing
and fruit drop, enhances the fruit ripening and has other advantages (Zaid, 1999).
Behseresht et al. (2007) reported that the thinning at kimri stage had no significant effects
on fruit quality and quantity when compared with that at pollination stage. Although,
removal of one third (control and strand-tip) of strands reduced yield; this treatment
increased fruits in top grade. Sayyahpoor (2002) reported that cutting 5, 10 or 15 cm of
the strand one week after pollination had no effect on fruit volume, but thinning intensity
@ 10 and 15 cm resulted in significant increases in fruit length and in fruit weight and
diameter of „Sayer‟ dates, respectively. Samavi (1998) also found that in „Mordasang‟
cultivar, removing the tip of strands @ 10 or 15 cm levels 3 weeks after pollination
improved the fruit size and weight but without affecting the fruit quality parameters such
as TSS and total sugar and also seed weight and volume. Furthermore, it has been
indicated that in „Shahani‟ cultivar, cutting back one third of the tip or central strands at
the beginning of kimri stage (identical to the treatments used in our study) increased the
fruit weight and length, pulp to seed ratio, fruit water content and TSS but did not affect
fruit diameter (Tavakkoli et al., 1994). It was also found that in „Samani‟ cultivar,
removing one third of the tips or central strands eight weeks after pollination resulted in
significant increases in fruit weight, length and diameter, pulp weight and fruit TSS
percentage. Khademi (1998) reported that cutting back one third of the central strands at
pollination time is much more effective to increase the fruit size and quality and
accelerating the ripening period of „Kabkaab‟ dates than the same treatment at the time of
bunch lowering at mid kimri stage. Hence in date palm fruit thinning is considered as an
important management practice to hasten the maturity or ripening and improves the
physical and biochemical composition by reducing the competition in remaining fruits.
The research findings described in the preceding lines throw light on the status and
challenges faced by date palm industry in Pakistan. It also suggested making some plan to
combat these challenges; therefore, the current studies were intended and executed.
32
Chapter-3 MATERIAL AND METHODS
The research studies reported in this manuscript were conducted during 2011-2012 on
two date palm cultivars including ‘Hillawi’ (Slide 3.1) and ‘Khadrawi’ (Slide 3.2),
commercially grown in Punjab, Pakistan. On the basis of texture, these are soft date
cultivars but completely consumed at khalal stage due to occurrence of monsoon rains at
the time of harvesting and/or ripening during the months of mid-July to August, which is
a peak monsoon period that badly affects the production, processing and quality of these
date palm cultivars.
Slide 3.1: Mature fruit of date palm at final kimri stage cv. Hillawi
Slide 3.2: Mature fruit of date palm at final kimri stage cv. Khadrawi
33
3.1 Experimental site description
The research work reported in this manuscript was conducted in the Experimental Fruit
Orchard Square Number 9 and Post Graduate Agricultural Research Station (PARS) and
Pomology Laboratory Institute of Horticultural Sciences, University of Agriculture
Faisalabad, Pakistan. Analytical work was conducted in the laboratories of Post-harvest
Research Centre, Ayub Agricultural Research Institute (AARI), Faisalabad, Pakistan,
Central High-Tech Laboratory, University of Agriculture Faisalabad and Biological and
Bioassay Laboratory of Chemistry and Biochemistry Department, University of
Agriculture Faisalabad, Pakistan.
3.2 Experimental material
The plants of two date palm (Phoenix dactylifera L.) cultivars ‘Hillawi’ and ‘Khadrawi’
having the age of about 20-22 years grown at Experimental Fruit Orchard Sq. No. 9 and
Post Graduate Agricultural Research Station (Latitude 31o-26´ N, Longitude 73
o-06´ E
and Altitude 184.4 m), Institute of Horticultural Sciences, University of Agriculture
Faisalabad, Punjab Province, Pakistan, were selected for this study work. All the selected
plants were uniform in size, manually pollinated and uniform agronomic practices
(fertilizers application and irrigation) were adopted throughout the period of
investigations (2011-2012).
3.3 Experimental details
3.3.1a Evaluating the potential of ethephon on ripening acceleration and fruit
quality of date palm at kimri stage.
Twenty one trees of each cultivar (Hillawi and Khadrawi) with uniform size and age were
selected as experimental material under RCBD (Factorial) with three replications (2
bunches per replication). A liquid plant growth regulator [(Ethephon 480g/L SL (48%
m/v)] was purchased from Shanghai Mingdou Agrochemical Co., Ltd. China. A wooden
step ladder was used for climbing up on the date palm trees during the experimentation.
Following concentrations of ethephon [(Ethephon 480g/L SL (48% m/v)] were applied at
final kimri stage with following treatments given as under.
T1: Control (without ethephon application)
T2: Ethephon spray @ 2 ml/L at final kimri stage
T3: Ethephon spray @ 4 ml/L at final kimri stage
T4: Ethephon spray @ 6 ml/L at final kimri stage
T5: Ethephon injection @ 1 ml/bunch at final kimri stage
T6: Ethephon injection @ 2 ml/bunch at final kimri stage
34
T7: Ethephon injection @ 3 ml/bunch at final kimri stage
3.3.1.1a Method of spray
For spraying ethephon was dissolved in 1000 ml water. Tween-20 at 0.01% was added as
surfactant with foliar application as a wetting agent. For each bunch 250 ml solution was
used as a spraying material. Spraying was done with a hand carrying plastic sprayer
having the capacity of 500 ml.
3.3.1.2a Method of injection
For injection a small pit was made in the peduncle with a sharp budding knife made up of
stainless steel. The pit was made 20 cm away from the start of fruiting and ethephon
solution was injected into the pit with the help of a 5 ml BD Plastipak TM Luer Tip
syringe (diameter: 12.05 mm) mounted with stainless steel needle having the dimension
of (21G×11/2”-0.08×40 mm). After injection pit was covered with cellotape to avoid any
contamination.
3.3.1.3a Fruit harvesting
During the entire harvesting season, rutab/ripe fruits were periodically collected from the
selected bunches and weighed. Fruits showing soft brownish tip were considered as ripe
or rutab fruits. From each replication 100 rutab fruits were randomly selected for physical
and biochemical analysis.
3.3.1b Effectiveness of ethephon on the ripening acceleration and physico-
chemical characteristics of date palm at khalal stage.
3.3.1.1b Methodology
Same methodology was adopted as mentioned in the section 3.3.1.1a regarding the
ethephon treatments, concentrations used, application procedure and fruits harvesting. In
this part of experiment, treatments were applied at color break stage (early khalal stage)
of both date palm cultivars.
35
Khadrawi fruit at final kimri stage Hillawi fruit at final kimri stage
Calibration of ethephon Ethephon spray
Removal of thorns Scaling for injection
36
Making pit for injection Injecting ethephon in the peduncle
Covering of injection site
Slide-3.3: Application of ethephon by foliar spray and injection
37
3.3.2 Exploring the role of thinning practices on the ripening and fruit quality of
date palm.
In this experiment, seven trees of each cultivar (Hillawi and Khadrawi) with uniform size
and age were selected as experimental material under RCBD (factorial) with three
replications (2 bunches per replication). The treatments detail is given below.
T1: Control (no thinning)
T2: 20% removal of central strands
T3: 30% removal of central strands
T4: 20% shortening of terminal tips
T5: 30% shortening of terminal tips
T6: 20% removal of central strands + 20% shortening of terminal tips (T2+T4)
T7: 30% removal of central strands + 30% shortening of terminal tips (T3+T5)
3.3.2.1 Method and time of thinning
Thinning was performed with a small hand carrying pruning scissor made up of stainless
steel at early kimri stage (4 weeks after pollination). Thinning was carried out with
removal of central strands and shortening of terminal tips with different intensities and
combination of both. For the removal of central strands, firstly these were counted from
each selected bunch for performing the required intensity of thinning. Whereas, for
shortening of terminal tips, the strands length was measured with a hand scale from
selected bunches and then the required intensity of thinning was executed as mentioned
above in the treatments layout.
3.3.2.2 Fruit harvesting
During the entire harvesting season, rutab/ripe fruits were periodically collected from the
selected bunches and weighed. Fruits showing soft brownish tip were considered as ripe
or rutab fruits. From each replication 100 rutab fruits were randomly selected for physical
and biochemical analysis.
38
Performing thinning operation Removal of central strands
Removal of terminal tips Tagging of thinned bunches
Slide-3.4: Performing strands thinning practices at early kimri stage
39
3.3.3 Ripening and quality assessment of date palm fruit by the influence of hot
water treatment.
The experiment was comprised of five treatments under completely randomized design
(factorial) with three replications and two date palm cultivars ‘Hillawi and ‘Khadrawi’.
The treatments detail is given as under.
T1: Control T4: HWD at 65oC for 5 min
T2: HWD at 65oC for 1 min T5: HWD at 65
oC for 7 min
T3: HWD at 65oC for 3 min
3.3.3.1 Fruit collection and hot water treatments procedure
The fruit was collected at khalal stage from Post Graduate Agricultural Research Station,
Institute of Horticultural Sciences, University of Agriculture Faisalabad, Pakistan. The
collected fruits along with strands were brought to the laboratory for further procedure.
After cleaning and washing, fruits of both cultivars (Hillawi and Khadrawi) were dipped
in hot water at a fixed temperature of 65oC but timing was ascending to the treatments.
The treated samples were placed under ambient conditions (25 ± 4oC, 70-75% R.H.) for
ripening until the fruit reached at tamer stage. From each replication 100 tamar fruits
were randomly selected for physical and biochemical analysis.
3.3.4 Effects of different chemicals on the ripening behaviour and fruit quality of
date palm.
The experiment was comprised of nine treatments under completely randomized design
(factorial) with three replications and two date palm cultivars ‘Hillawi and ‘Khadrawi’.
The treatments detail is given below.
T1: Control (without chemical dipping)
T2: Dipping in 2% acetic acid solution
T3: Dipping in 3% acetic acid solution
T4: Dipping in 2% NaCl solution
T5: Dipping in 3% NaCl solution
T6: Dipping in 2 ml/L ethephon solution
T7: Dipping in 4 ml/L ethephon solution
T8: Dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon solution
T9: Dipping in 3% acetic acid+3% NaCl+4 ml/L ethephon solution
3.3.4.1 Fruit collection and treatments procedure
The fruits were collected at khalal stage from Post Graduate Agricultural Research
Station, Institute of Horticultural Sciences, University of Agriculture Faisalabad,
40
Pakistan. The collected fruits were brought to the laboratory for further procedure. After
cleaning and washing fruits were immersed in the aforementioned chemicals solutions for
4 to 5 minutes at ambient temperature (25 ± 4oC, 70-75% R.H.) and then incubated in an
aerated incubator at 40 ± 1oC for 72 h (Chakraverty et al., 2003). After incubation 100
tamar fruits were randomly selected for physical and biochemical analysis.
3.3.5 Sun-drying techniques (SDTs) affected the fruit quality attributes of dates
picked at rutab stage cv. Hillawi.
The experiment was comprised of five treatments under completely randomized design
with three replications (5 kg fruit per replication) in Hillawi date palm cultivar. The
treatments detail is given below.
SDT1: Control (DSE without covering and removal during night)
SDT2: DSE on mat and covered with polythene sheet during night
SDT3: DSE on mat and removal in baskets during night
SDT4: DSE on mat with removal in baskets and covered during night
SDT5: DSE on mat and removal with mats during night
3.3.5.1 Fruit collection and treatments procedure
The fruit of Hillawi cultivar was harvested at rutab stage from Post Graduate Agricultural
Research Station, Institute of Horticultural Sciences, University of Agriculture
Faisalabad, Pakistan (Latitude 31o-26´ N, Longitude 73
o-06´ E and Altitude 184.4 m).
The collected fruit was dried under direct sun light exposure (DSE) by adopting different
sun drying techniques (SDTs). The sun drying practices were carried out continuously for
6 to 8 days (depends on daily temperature) until fruit goes to <25% moisture level. From
each replication 100 tamar fruits were randomly selected for biochemical analysis.
3.4 Detail of field work (observations recorded)
The detail of all collected data during the research work is given as under.
3.4.1 External/physical observations recorded:
All the external/physical parameters were collected randomly from the tagged fruit
bunches/experimental units. The following parameters were recorded:
3.4.1.1 Time taken to reach the fruit at final kimri stage (days)
Time taken to reach the fruit at final kimri stage (full hard green fruit) after the treatments
application was recorded from tagged bunches and then average was calculated.
3.4.1.2 Time taken to reach the fruit at final khalal stage (days)
Time taken to reach the fruit at khalal stage (yellow fruit) after the treatments application
was recorded from the tagged bunches and then average was calculated.
41
3.4.1.3 Time taken to reach the fruit at rutab stage (days)
Time taken to reach the fruit at rutab stage (fruit showing soft/brown tip portion) after the
treatments applications were recorded from the tagged bunches of each treatment and
then average was calculated.
3.4.1.4 Time taken to reach the fruit at tamar stage (days)
Time taken to reach the fruit at tamar stage after the treatments application was recorded
from the tagged experimental units and then average was calculated.
3.4.1.5 Rutab fruit yield per bunch (kg)
Rutab fruit yield per bunch was calculated from tagged bunches with a digital weighing
balance during the entire harvesting season and then average was calculated. Fruit tips
showing soft/brown portion are considered as rutab/ripe fruits.
3.4.1.6 Uniform fruit ripening index (%)
Uniform fruit ripening index was calculated by using the following formula as given
below.
Uniform fruit ripening index (%) = X/Y×100
Where,
X = Number of ripe fruits Y = Total number of fruits
3.4.1.7 Fruit weight (g)
For fruit weight, thirty fruits were randomly selected from each replication and weighed
with digital balance and then average of individual fruit was calculated.
3.4.1.8 Fruit length (mm)
The fruit length of thirty selected fruits was recorded with a digital vernier calliper and
then average of individual fruit length was calculated.
3.4.1.9 Fruit width (mm)
The fruit width of thirty selected fruits was recorded with a digital vernier calliper and
then average of individual fruit width was calculated.
3.4.1.10 Fruit flesh weight (g)
For calculating the flesh weight, cut thirty selected fruits with a knife and remove the
stone then weighed with digital balance and calculate the mean value.
3.4.1.11 Fruit stone weight (g)
After removing the flesh from thirty selected fruits, stone weight was measured with a
digital balance and then average was calculated.
42
3.4.1.12 Fruit weight loss (%)
For the determination of fruit weight loss, fruits were weighed before imposing the
treatments which served as the initial fruit weight. The loss in weight was recorded at the
final day of observation which served as the final fruit weight. The loss in weight was
determined by the following formula and expressed as percentage.
Fruit weight loss = Initial fruit weight – Fruit weight at final observation × 100
Initial fruit weight
3.4.2 Biochemical analysis
3.4.2.1 Moisture determination (%)
Moisture percentage was determined by an automatic electronic computer operated
moisture tester (Brabender® MT-C, made by GmbH & Co. KG, Germany).
3.4.2.2 Total soluble solids concentration (oBrix)
Total soluble solids concentration was measured by using digital refractometer (ATAGO,
RX-5000, Japan) at room temperature (20oC) and readings were expressed as
oBrix.
3.4.2.3 Ascorbic acid (mg 100 g-1
)
Ascorbic acid contents were determined following the method described by Ruck (1961)
by titrating the extracted juice samples against 2, 6-dichlorophenolindophenol dye, to
light pink color end point, persisted at least for 15 seconds. The vitamin-C was calculated
by using following formula as given below.
Ascorbic acid / Vit. C (mg 100 g-1
) = 1 × R1 × V × 100
R × W × V1
R: ml of dye used to titrate against 2.5 ml (1 ml standard ascorbic acid + 1.5 ml 0.4%
oxalic acid) of reference solution (standard reading)
R1: ml of dye used to titrate against V1 of aliquot (sample reading)
V: Volume of the aliquot made by 0.4% oxalic acid
V1: ml of juice taken for titration
W: ml of aliquot used for titration
Dye was prepared by adding 42 mg NaHCO3 and 52 mg 2, 6-dichlorophenol indophenols
in a 200 ml volumetric flask. Volume was made up to the mark by adding distilled water.
It was filtered and used as freshly prepared dye.
3.4.2.4 Total titratable acidity (%)
Total titratable acidity (TA) was determined by the method described by Hortwitz (1960)
by titrating the extracted juice samples against 0.1N NaOH, using 2-3 drops of
phenolphthalein as an indicator till pink color end point was achieved. Total acidity was
measured according to the following formula:
43
Total titratable acidity (%) = 0.1N NaOH used × 0.0064 × 100
ml of juice taken for titration
3.4.2.5 Total tannins
Total tannins contents were estimated according to the method of (AOAC, 1980) by
titrating the extracted fruit samples with standard potassium permanganate solution by
using indigo caramine as in indicator until colour changed to faint pink and values were
expressed as percentage.
3.4.2.6 Total phenolics
Total phenolic contents (TPC) were calculated by using Folin-Ciocalteu reagent method
as reported by Ainsworth and Gillespie (2007). The FC-reagent (10 mL) was dissolved in
distilled water to make the solution 100 mL. In each sample (100 mL), FC-reagent (200
μL) was added and vortex thoroughly. The 700 mM Na2CO3 (800 μL) was added into
each sample and incubated at room temperature for 2 h. Sample (200 μL) was transferred
to a clear 96-well plate and absorbance of each well was measured at 765 nm. Amount of
TPC was calculated using a calibration curve for Gallic acid. The results were expressed
as Gallic acid equivalent.
3.4.2.7 Total antioxidants
Total antioxidants activity of the date fruits (skin+pulp) was assessed by measuring their
scavenging abilities to 2, 2-diphenyl-1-picrylhydrazyl stable radicals as described by
Amira et al. (2012). The absorbance was read against blank at 517 nm using micro-plate
ELISA reader (BioTek, USA). Inhibition of free radical by DPPH in percent was
calculated by following formula:
I % = (Ablank -Asample /Ablank) × 100
Where Ablank is the absorbance of the control reaction mixture excluding fruit sample, and
Asample is the absorbance of the test compounds. IC50 values, which represented the
concentration of date fruit extracts that caused 50% neutralization of DPPH radicals, were
calculated from the plot of inhibition percentage against concentrations.
3.4.2.8 Total flavonoids
Flavonoids were determined by the method of Kim et al. (2003). Distilled water (4 ml)
was added to 1 ml of extracted aliquot. Then, 5% sodium nitrite solution (0.3 ml) was
added, followed by 10% aluminum chloride solution (0.3 ml). Test tubes were incubated
at ambient temperature for 5 min, and then 2 ml of 1M sodium hydroxide were added to
the mixture and then the volume of reaction mixture was made up to 10 ml with distilled
water. The mixture was thoroughly vortex and the absorbance of the pink colour
44
developed was determined in a UV-visible spectrophotometer (IRMECO, U2020-
Germany) at 510 nm. A calibration curve was prepared with catechin and the results were
expressed as mg catechin equivalents. All the measurements were taken in triplicate and
the mean values were calculated.
3.4.2.9 Estimation of sugars through HPLC
For the estimation of sugars date fruit was extracted from the date flesh (2 g) in HPLC
grade ethanol (80% v/v). The available extracts were then centrifuged at 13000 xg for 10
min and then supernatants were separated and analysed by high performance liquid
chromatography (HPLC).
Liquid chromatographic (LC) separation was carried out at room temperature on a Razex
RCM-Monosaccharide Ca+2, Phenomenex column with flow rate of 0.60 ml/min at 80oC.
The mobile phase was 100% double distilled water (DDH2O). The HPLC was connected
to a refractive index detector (ReID) RID-10 AL (Shimadzu, Japan) having the range of
(bipolar, 1250 mV,) with peak width of 0.200 min. Identified sugars were quantified on
the basis of peak areas of external standards consisting of glucose (1%), fructose (1%)
and sucrose (1%) solutions. Reducing sugars were calculated as a sum of glucose and
fructose values and total sugars were calculated by sum of glucose, fructose and sucrose.
Each sample was carried out from integrated peak areas of the sample against the
corresponding standard graph. Results were expressed as percentage of fresh weight.
3.4.3 Organoleptic evaluation
Organoleptic evaluation of the fruit for color, taste, texture, astringency, firmness and
overall acceptability was performed using the 5 point hedonic scale. Five master level
students were chosen from the Institute of Horticultural Sciences, as panelists who were
asked to mark the following parameters by using the 5 point hedonic scale:
Product: _____________ Variety: __________________ Date: ________________
Name of Judge:_________________________ Signature: _______________________
Please follow the numerical system for scoring the samples.
Very poor ---------------1 Good -------------------- 4
Poor ----------------------2 Excellent-----------------5
Satisfactory-------------- 3
Please do not disturb the sequence of the samples provided.
Please wash the tongue before testing next sample, with water provided.
45
Table 3.1 Organoleptic evaluation of Hillawi and Khadrawi date palm cultivars.
Sample
No.
Colour Taste Texture Astringency Firmness Overall
acceptability
1
2
3
4
5
3.5 Statistical analysis
The collected data were statistically analyzed using computer software MSTAT-C.
Analysis of variance was used to test the significance of variance. While difference
among treatment means were compared using LSD test (p = 0.05) (Steel et al., 1997).
Figure 3.1 Average meteorological data during two seasons (2011-2012) at
experimental site of date palm orchard.
0
20
40
60
80
100
120
140
Feb March April May June July August
Rela
tive h
um
idit
y (
%)
RH Temp Sunshine Wind speed Total Rain fall
46
Chapter-4 RESULTS AND DISCUSSION
4.1a Study-1 Evaluating the potential of ethephon on ripening acceleration and
fruit quality of date palm at kimri stage.
4.1.1a Results
4.1.1.1a Fruit maturity/ripening traits
4.1.1.1.1a Time taken to reach the fruit at late khalal stage (days)
Statistically significant differences (p ≤ 0.05) were found regarding the effects of
ethephon treatments and cultivars while interaction between them showed non-significant
results for time taken to reach the fruit at khalal stage (Figure 4.1a). Higher
concentrations of ethephon (spray and injection) accelerate the fruit maturity period two-
fold as compared to lower doses of ethephon in both date palm cultivars. The fruits those
were sprayed with ethephon @ 6 ml/L and 4 ml/L took shorter time (15.25 and 16.25
days) to complete the period from final kimri to late khalal stage, respectively and these
were statistically at par with each other. Whereas, more time of 27.50 days were noted in
the untreated fruits to complete the period from final kimri to late khalal stage. The fruits
of Hillawi cultivar took shorter time of 19.76 days to accomplish the period from final
kimri to late khalal stage as compared to the fruits of Khadrawi where more time of 22.92
days were noted to complete that period. Meanwhile, fruits those were sprayed with
ethephon @ 2 ml/L and by injection @ 3 ml/bunch showed intermediate effect in
accelerating the fruit maturity period (time taken to reach the fruit at late khalal stage) of
both date palm cultivars.
4.1.1.1.2a Time taken to reach the fruit at rutab stage (days)
The analyzed data presented in Figure 4.2a showed significant differences at p ≤ 0.05
regarding the effects of ethephon treatments and cultivars while their interaction was
found non-significant for time taken to reach the fruit at rutab stage. Higher
concentrations of ethephon (spray and injection) speed up the process of fruit maturity
two-fold than lower doses of ethephon in both date palm cultivars. The fruits those were
sprayed with ethephon @ 6 ml/L took shorter time of 32.83 to complete the period from
final kimri to rutab stage followed by fruits those were sprayed with ethephon @ 4 ml/L.
Whereas, more time of 47.66 and 46.25 days were recorded in the fruit those were
untreated and by ethephon injection @ 1 ml/bunch, respectively to complete the period
from final kimri to rutab stage and these were at par with each other. The fruits of Hillawi
47
cultivar took shorter time of 38.59 days to accomplish the period from final kimri to rutab
stage as compared to the fruits of Khadrawi where 41.35 days were noted to complete that
period. In the meanwhile, fruits sprayed with ethephon @ 2 ml/L and by injection @ 3
ml, 2 ml/bunch showed intermediate effect on time taken to reach the fruit at rutab stage
of both date palm cultivars.
4.1.1.1.3a Rutab fruit yield per bunch (kg)
Rutab fruit yield per bunch showed significant differences at p ≤ 0.05 regarding the
effects of ethephon treatments and cultivars while interaction between them was found
non-significant (Figure 4.3a). The increased concentration of ethephon also increased the
rutab fruit yield per bunch in both cultivars. Higher rutab fruit yield of 7.78 kg per bunch
was recorded in the fruits those were sprayed with ethephon @ 6 ml/L followed by fruits
those were sprayed with ethephon @ 4 ml/L. While, minimum rutab fruit yield of 1.91,
2.13 and 2.47 kg per bunch was noted in the fruits those were untreated and by injection
@ 1ml and 2ml/bunch, respectively and these were at par with each other. More rutab
fruit yield (4.43 kg) per bunch was noted in Hillawi cultivar as compared to the fruits of
Khadrawi where rutab fruit yield of 3.31 kg per bunch was recorded. Similarly, fruits
sprayed with ethephon @ 2 ml/L and by injection @ 3 ml, 2 ml/bunch showed
intermediary effect on rutab fruit yield of both date palm cultivars.
4.1.1.1.4a Uniform fruit ripening index (%)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of
ethephon treatments and cultivars while interaction between them showed non-significant
results for uniform fruit ripening index (Figure 4.4a). The rate of uniform fruit ripening
increased as well as the concentration of ethephon increased. Fruits those were sprayed
with ethephon @ 6 ml/L and 4 ml/L showed higher uniform fruit ripening indexes of
62.35 and 60.46%, respectively and these were statistically at par with each other. While,
lower uniform fruit ripening index of 34.14% was recorded in the untreated fruits and
these were at par with the fruits those were treated with ethephon injection @ 1 ml/bunch
where uniform fruit ripening index was 35.24%. The Hillawi fruits attained higher
uniform fruit ripening index of 50.01% as compared to the fruits of Khadrawi where fruit
ripening index of 44.75% was measured. The in
termediate effect was observed in fruits those were sprayed with ethephon @ 2 ml/L and
by injection @ 3 ml, 2 ml/bunch regarding the uniform fruit ripening of both date palm
cultivars.
48
Figure 4.1a Effects of different ethephon concentrations (spray and injection) on
time taken (days) from final kimri to late khalal stage of Hillawi and
Khadrawi date palm fruit ± S.E.
Figure 4.2a Effects of different ethephon concentrations (spray and injection) on
time taken (days) from final kimri to rutab stage of Hillawi and
Khadrawi date palm fruit ± S.E.
0
5
10
15
20
25
30
35
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Tim
e t
ak
en
to
kh
ala
l st
ag
e (
da
ys)
Hillawi Khadrawi
0
10
20
30
40
50
60
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Tim
e t
ak
en
to
ru
tab
sta
ge (
da
ys)
Hillawi Khadrawi
49
Figure 4.3a Effects of different ethephon concentrations (spray and injection) on
rutab fruit yield per bunch (kg) of Hillawi and Khadrawi date palm
fruit ± S.E.
Figure 4.4a Effects of different ethephon concentrations (spray and injection) on
uniform fruit ripening index (%) of Hillawi and Khadrawi date palm
fruits ± S.E.
0
1
2
3
4
5
6
7
8
9
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Ru
tab
yie
ld p
er b
un
ch
(k
g)
Hillawi Khadrawi
0
10
20
30
40
50
60
70
80
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Un
iform
fru
it r
ipen
ing
in
dex
(%
)
Hillawi Khadrawi
50
4.1.1.2a Fruit physical traits
4.1.1.2.1a Fruit weight (g)
Statistically non-significant differences were found at p ≥ 0.05 regarding the effects of
ethephon treatments and interaction while both cultivars showed significant results for
fruit weight (Figure 4.5a). The fruits of Hillawi attained higher weight (7.19 g) as
compared to fruits of Khadrawi where fruit weight of 6.32 g was recorded.
4.1.1.2.2a Fruit length (mm)
The analyzed data presented in Figure 4.6a showed non-significant differences (p ≥ 0.05)
regarding the effects of ethephon treatments and interaction while both cultivars differ
significantly for fruit length. Regarding the response of cultivars, Hillawi fruits attained
maximum length (36.52 mm) than the fruits of Khadrawi where fruit length of 32.56 mm
was noted.
4.1.1.2.3a Fruit width (mm)
Effects of ethephon treatments and interaction were found non-significant (p ≥ 0.05)
while both cultivars showed significant results for fruit width (Figure 4.7a). The fruits of
Khadrawi cultivar attained higher width (22.50 mm) as compared to the fruits of Hillawi
where fruit width of 18.52 mm was noted.
4.1.1.2.4a Fruit flesh weight (g)
Statistically non-significant differences (p ≥ 0.05) were found regarding the effects of
ethephon treatments and interaction while both cultivars showed significant results for
fruit flesh weight (Figure 4.8a). The fruits of Hillawi attained higher flesh weight (6.17 g)
than the fruits of Khadrawi where flesh weight of 5.62 g was recorded.
4.1.1.2.5a Fruit pit weight (g)
Fruit pit weight showed non-significant differences at p ≥ 0.05 regarding the effects of
ethephon treatments and interaction while a significant differences was found in cultivars
(Figure 4.9a). The fruits of Hillawi attained higher pit weight (1.02 g) as compared to the
fruits of Khadrawi where pit weight of 0.69 g was measured.
51
Figure 4.5a Effects of different ethephon concentrations (spray and injection) on
fruit weight (g) of Hillawi and Khadrawi date palm ± S.E.
Figure 4.6a Effects of different ethephon concentrations (spray and injection) on
fruit length (mm) of Hillawi and Khadrawi date palm ± S.E.
4
4.5
5
5.5
6
6.5
7
7.5
8
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
it w
eig
ht
(g)
Hillawi Khadrawi
30
32
34
36
38
40
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
it l
en
gth
(m
m)
Hillawi Khadrawi
52
Figure 4.7a Effects of different ethephon concentrations (spray and injection) on
fruit width (mm) of Hillawi and Khadrawi date palm ± S.E.
Figure 4.8a Effects of different ethephon concentrations (spray and injection) on
flesh weight (g) of Hillawi and Khadrawi date palm fruit ± S.E.
10
12
14
16
18
20
22
24
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
it w
idth
(m
m)
Hillawi Khadrawi
5
5.2
5.4
5.6
5.8
6
6.2
6.4
6.6
6.8
7
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
it f
lesh
weig
ht
(g)
Hillawi Khadrawi
53
Figure 4.9a Effects of different ethephon concentrations (spray and injection) on
pit weight (g) of Hillawi and Khadrawi date palm fruit ± S.E.
4.1.1.3a Fruit biochemical traits
4.1.1.3.1a Fruit moisture content (%)
The analyzed data presented in Figure 4.10a showed statistically significant differences (p
≤ 0.05) regarding the effects of ethephon treatments, cultivars and their interaction for
fruit moisture content. The progression of ripening decreased the fruit moisture contents.
Higher ethephon concentrations showed more reduction in fruit moisture content as
compared to lower concentrations in both cultivars. Lower level of moisture content
36.48% was noted in the fruit of Hillawi those were sprayed with ethephon @ 6 ml/L
followed by fruits sprayed with ethephon @ 4 ml/L. Whereas, higher level of moisture
content (39.50 and 39.22%) was recorded in the untreated fruits and those were treated
with ethephon injection @ 1 ml/bunch and these were statistically similar to each other.
The fruits of Hillawi showed lower level of moisture content (37.86%) than the fruits of
Khadrawi where moisture contents of 38.72% were noted. The fruits those were sprayed
with ethephon @ 2 ml/L and by injection @ 3 ml/bunch showed intermediate effect
regarding the fruit moisture content of both date palm cultivars.
4.1.1.3.2a Total soluble solids concentration (oBrix)
Total soluble solids concentration in fruit showed significant differences (p ≤ 0.05)
regarding the effects of ethephon treatments and cultivars while interaction between them
0
0.2
0.4
0.6
0.8
1
1.2
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Hillawi Khadrawi
54
was found non-significant (Figure 4.11a). Total soluble solids increased positively with
the progression of fruit ripening. The fruits those were sprayed with ethephon @ 4 ml/L
showed higher amount of total soluble solids contents (9.45 oBrix) followed by fruits
sprayed with ethephon @ 6 ml/L. While, lower amount of TSS contents of 7.87 and 8.04
oBrix were noted in untreated fruits and these were at par with the fruits those were
treated with ethephon injection @ 1 ml/bunch where TSS contents were 8.04 oBrix.
Hillawi fruits showed higher amounts of TSS contents (9.08 oBrix) as compared to the
fruits of Khadrawi where TSS contents of 8.37 oBrix were recorded. The intermediary
effect on TSS contents was noted in fruits those were sprayed with ethephon @ 2 ml/L
and by injection @ 3 ml/bunch in both date palm cultivars.
4.1.1.3.3a Total titratable acidity (%)
Statistically significant differences (p ≤ 0.05) were found regarding the effects of
ethephon treatments and cultivars while their interaction showed non-significant results
for total titratable acidity (Figure 4.12a). Lower levels of total titratable acidity (0.174,
0.203 and 0.213%) were recorded in the fruits those were sprayed with ethephon @ 4, 6
and 2 ml/L and these were statistically similar to each other. Whereas, higher levels of
total titratable acidity (0.287%) was noted in the untreated fruits and these were at par
with the fruits those were treated with ethephon injection @ 1ml/bunch, 2ml/bunch and
3ml/bunch where titratable acidity values were 0.276, 0.256 and 0.246%, respectively and
these were at par with each other. Hillawi fruits showed lower level of titratable acidity
(0.207%) as compared to the fruits of Khadrawi where titratable acidity of 0.266% was
recorded.
4.1.1.3.4a Ascorbic acid (mg 100 g-1
)
The analyzed data presented in Figure 4.13a showed significant differences at p ≤ 0.05
regarding the effects of ethephon treatments and cultivars while interaction between them
was found non-significant for ascorbic acid. Higher ascorbic acid contents (1.39 and 1.29
mg 100 g-1
) were recorded in the fruits those were sprayed with ethephon @ 4 ml/L, 6
ml/L. While, lower amounts of ascorbic acid of 0.94 mg 100 g-1
were noted in control
fruits and these were at par with the fruits those were treated with ethephon injection @ 1
ml/bunch where level of ascorbic acid values was 1.01 mg 100 g-1
recorded. The Hillawi
fruits showed higher amounts of ascorbic acid (1.21 mg 100 g-1
) as compared to the fruits
of Khadrawi where ascorbic acid contents of 1.12 mg 100 g-1
were noted. The fruits those
were sprayed with ethephon @ 2 ml/L and by injection @ 3 and 2 ml/bunch showed
intermediate effect regarding ascorbic acid in both date palm cultivars.
55
Figure 4.10a Effects of different ethephon concentrations (spray and injection) on
fruit moisture content (%) of Hillawi and Khadrawi date palm fruit
± S.E.
Figure 4.11a Effects of different ethephon concentrations (spray and injection) on
total soluble solids concentration (oBrix) of Hillawi and Khadrawi
date palm fruit ± S.E.
30
32
34
36
38
40
42
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Mo
istu
re c
on
ten
t (%
)
Hillawi Khadrawi
0
2
4
6
8
10
12
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
TS
S (
oB
rix
)
Hillawi Khadrawi
56
Figure 4.12a Effects of different ethephon concentrations (spray and injection)
on total titratable acidity (%) of Hillawi and Khadrawi date palm
fruit ± S.E.
Figure 4.13a Effects of different ethephon concentrations (spray and injection)
on ascorbic acid (mg 100 g-1
) of Hillawi and Khadrawi date palm
fruit ± S.E.
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Acid
ity
(%
)
Hillawi Khadrawi
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Asc
orb
ic a
cid
(m
g 1
00
g-1
)
Hillawi Khadrawi
57
4.1.1.3.5a Glucose (%)
The analyzed data presented in Figure 4.14a showed significant differences regarding the
effects of ethephon treatments and cultivars while interaction between them was found
non-significant for glucose. Higher levels of glucose (23.32, 22.81 and 22.40%) were
noted in fruits those were sprayed with ethephon @ 4 ml/L, 6 ml/L and 2 ml/L and these
were at par with each other. While, lower amounts of glucose (18.25%) were recorded in
fruits those were untreated and these were at par with the fruits those were treated with
ethephon injection @ 1 ml/bunch where glucose of 18.52% were noted. The fruits of
Hillawi showed higher glucose contents (21.96%) as compared to the fruits of Khadrawi
where glucose of 20.20% was noted. Fruits treated with ethephon injection @ 3 ml/bunch
showed intermediate effect regarding glucose of both date palm cultivars.
4.1.1.3.6a Fructose (%)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of
ethephon treatments and cultivars while interaction between them showed non-significant
results for fructose (Figure 4.15a). Higher fructose contents (21.65 and 21.19%) were
recorded in fruits those were sprayed with ethephon @ 4 ml/L and 6 ml/L, respectively
and these were at par with each other. Whereas, lower level of fructose (17.08%) were
noted in fruits those were untreated and these were at par with the fruits those were
treated with ethephon injection @ 1 ml/bunch. Hillawi fruits showed higher amounts of
fructose contents (20.24%) than the fruits of Khadrawi where fructose of 19.06% were
recorded. Fruits those were sprayed with ethephon @ 2 ml/L and by injection @ 3
ml/bunch showed intermediary effect regarding the fructose on both date palm cultivars.
4.1.1.3.7a Sucrose (%)
Effects of ethephon treatments and cultivars showed significant differences (p ≤ 0.05)
while interaction between them were found non-significant regarding the sucrose (Figure
4.16a). Fruits those were sprayed with ethephon @ 4 ml/L and 6 ml/L showed higher
level of fructose (5.81 and 5.52%), respectively and these were at par with each other.
While, fruits those were untreated showed lower value of sucrose of 3.99%. The fruits of
Hillawi attained higher level of sucrose (5.21%) as compared to the fruits of Khadrawi
where sucrose of 4.55% was noted. The intermediate effect was recorded in fruits those
were sprayed with ethephon @ 2 ml/L and by injection @ 3 ml/bunch regarding the
fructose in both cultivars.
58
4.1.1.3.8a Reducing sugars (%)
Statistically significant differences (p≤0.05) were found regarding the effects of ethephon
treatments and cultivars while their interaction showed non-significant results for
reducing sugars (Figure 4.17a). Fruits those were treated with foliar spray @ 4 ml/L, 6
ml/L and 2 ml/L achieved higher values of reducing sugars (44.97, 44.00 and 43.47%),
respectively and these were at par with each other. Whereas, lower level of reducing
sugar contents (35.33%) were recorded in untreated fruits and these were at par with the
fruits those were treated with ethephon injection @ 1 ml/bunch where reducing sugars of
35.75% were noted. The fruits of Hillawi showed higher amounts of reducing sugars
(42.20%) than the fruits of Khadrawi where reducing sugars of 39.27% were recorded.
Meanwhile, fruits those were treated with ethephon injection @ 3 ml/bunch showed
intermediate effect on reducing sugars of both date palm cultivars.
4.1.1.3.9a Total sugars (%)
The analyzed data presented in Figure 4.18a showed significant differences at p≤0.05
regarding the effects of ethephon treatments and cultivars while interaction between them
was found non-significant for total sugars. The fruits those were sprayed with ethephon
@ 4 ml/L and 6 ml/L showed higher levels of total sugars of 50.78 and 49.52%,
respectively and these were at par with each other. While, fruits those were untreated
showed lower level of total sugars (39.32%) and these were at par with the fruits those
were treated with ethephon injection @ 1 ml/bunch where total sugars of 40.07% were
noted. Hillawi fruits attained higher level of total sugars (47.42%) as compared to the
fruits of Khadrawi where total sugars of 43.82% were recorded. The intermediary effect
regarding total sugars was noted in fruits those were sprayed with ethephon @ 2 ml/L and
by injection @ 3 ml/bunch in both date palm cultivars.
59
Figure 4.14a Effects of different ethephon concentrations (spray and injection)
on glucose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.15a Effects of different ethephon concentrations (spray and injection)
on fructose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
0
5
10
15
20
25
30
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Glu
co
se (
%)
Hillawi Khadrawi
0
5
10
15
20
25
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
cto
se (
%)
Hillawi Khadrawi
60
Figure 4.16a Effects of different ethephon concentrations (spray and injection)
on sucrose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.17a Effects of different ethephon concentrations (spray and injection)
on reducing sugars (%) of Hillawi and Khadrawi date palm fruit ±
S.E.
0
1
2
3
4
5
6
7
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Su
cro
se (
%)
Hillawi Khadrawi
0
10
20
30
40
50
60
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Red
ucin
g s
ug
ars
(%)
Hillawi Khadrawi
61
Figure 4.18a Effects of different ethephon concentrations (spray and injection)
on total sugars (%) of Hillawi and Khadrawi date palm fruit ± S.E.
4.1.1.4a Fruit phytonutritional traits
4.1.1.4.1a Total phenolics (mg GAE/100 g)
Total phenolics in the fruits at rutab stage showed significant differences (p ≤ 0.05)
regarding the effects of ethephon treatments and cultivars while interaction between them
was found non-significant (Figure 4.19a). Fruits those were sprayed with ethephon @ 4
ml/L and 6 ml/L showed higher amounts of total phenolics (158.72 and 152.50 mg
GAE/100 g), respectively and these were at par with each other. While, fruits those were
untreated showed lower amounts of total phenolics (116.57 mg GAE/100 g) and these
were at par with the fruits those were treated with ethephon injection @ 1 ml/bunch
where total phenolics of 121.71 mg GAE/100 g were noted. The fruits of Khadrawi
attained higher amounts of total phenolics (141.35 mg GAE/100 g) as compared to the
fruits of Hillawi where total phenolics of 132.37 mg GAE/100 g were recorded. The fruits
those were sprayed with ethephon @ 2 ml/L and by injection @ 3 ml/bunch showed
intermediate effect regarding the total phenolics in both date palm cultivars.
4.1.1.4.2a Total flavonoids (mg CEQ/100 g)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of
ethephon treatments and cultivars while interaction between them showed non-significant
results for total flavonoids in fruit at rutab stage (Figure 4.20a). Higher amounts of total
flavonoids (49.51 mg CEQ/100 g) were recorded in fruits those were sprayed with
0
10
20
30
40
50
60
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
To
tal
sug
ars
(%)
Hillawi Khadrawi
62
ethephon @ 4 ml/L. While, lower amounts of total flavonoids (21.29 mg CEQ/100 g)
were noted in control fruits and these were at par with the fruits those treated with
ethephon injection @ 1 ml/bunch and 2 ml/bunch where values of total flavonoids were
21.70 and 22.78 mg CEQ/100 g, respectively and these were at par with each other. The
Hillawi fruits attained higher amounts of total flavonoids (33.79 mg CEQ/100 g) as
compared to the fruits of Khadrawi where total flavonoids of 30.02 mg CEQ/100 g were
noted. The intermediate effect regarding the total flavonoids was observed in fruits those
were sprayed with ethephon @ 6, 2 ml/L and by injection @ 3 ml/bunch in both date
palm cultivars.
4.1.1.4.3a Total tannins (%)
The analyzed data presented in Figure 4.21a showed statistically significant differences (p
≤ 0.05) for total tannins regarding the effects of ethephon treatments and cultivars while
interaction between them was found non-significant. The fruit those were sprayed with
ethephon @ 4 ml/L and 6 ml/L showed lower levels of total tannins (0.48 and 0.52%) and
these were at par with each other. Whereas, higher amounts of total tannins (0.87%) were
noted in fruits those were untreated and these were at par with the fruits those were
treated with ethephon injection @ 1 ml/bunch where total tannins were 0.84%. The fruits
of Hillawi showed lower amounts of total tannins (0.63%) than the fruits of Khadrawi
where total tannin contents of 0.73% were recorded. The fruits those were sprayed with
ethephon @ 2 ml/L and by injection @ 3 ml/bunch showed intermediate effect regarding
the total tannins in both dates palm cultivars.
4.1.1.4.4a Total antioxidants (%)
Statistically significant differences (p ≤ 0.05) were found regarding the effects of
ethephon treatments and cultivars while interaction between them showed non-significant
results for total antioxidants activities in fruits at rutab stage (Figure 4.22a). Higher total
antioxidants activities of 61.79 and 59.78% were recorded in fruits those were sprayed
with ethephon @ 4 ml/L and 6 ml/L, respectively and these were at par with each other.
Whereas, lower total antioxidants activities (40.20%) were noted in untreated fruits and
these were at par with the fruits those were treated with ethephon injection @ 1 ml/bunch
where total antioxidants activities of 42.49% were recorded. The fruits of Khadrawi
showed higher total antioxidants activities (51.49%) as compared to the fruits of Hillawi
where total antioxidants activities of 48.16% were noted. The intermediary effect
regarding the total antioxidants activities was noted in fruits those were sprayed with
ethephon @ 2 ml/L and by injection @ 3, 2 ml/bunch in both date palm cultivars.
63
Figure 4.19a Effects of different ethephon concentrations (spray and injection)
on total phenolics (mg GAE/100 g) of Hillawi and Khadrawi date
palm fruit ± S.E.
Figure 4.20a Effects of different ethephon concentrations (spray and injection)
on total flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi date
palm fruit ± S.E.
0
20
40
60
80
100
120
140
160
180
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
TP
C (
mg
GA
E/1
00
g)
Hillawi Khadrawi
0
10
20
30
40
50
60
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
TF
C (
mg
CE
Q/1
00
g)
Hillawi Khadrawi
64
Figure 4.21a Effects of different ethephon concentrations (spray and injection)
on total tannins (%) of Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.22a Effects of different ethephon concentrations (spray and injection)
on total antioxidants (%) of Hillawi and Khadrawi date palm fruits
± S.E.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
To
tal
tan
nin
s (%
)
Hillawi Khadrawi
0
10
20
30
40
50
60
70
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
To
tal
an
tio
xid
an
ts (
%)
Hillawi Khadrawi
65
4.1b Study-1 Effectiveness of ethephon on the ripening acceleration
and physico-chemical characteristics of date palm at
khalal stage.
4.1.1b Results
4.1.1.1b Fruit maturity/ripening traits
4.1.1.1.1b Time taken to reach the fruit at late khalal stage (days)
Statistically significant differences (p ≤ 0.05) were found regarding the effects of
ethephon treatments and cultivars while interaction between them showed non-significant
results for time taken to reach the fruit at late khalal stage (Figure 4.23b ). Fruits those
were sprayed with ethephon @ 4 ml/L and 2 ml/L took shorter time of 9.25 and 11.58
days to complete the period from early khalal to late khalal stage, respectively and these
were statistically similar to each other. Whereas, fruits those were untreated took more
time (16.41 days) to accomplish that period and these were at par with the fruits those
were treated with ethephon injection @ 1 ml/bunch, 2 ml/bunch and 3 ml/bunch those
took 15.00, 14.75 and 14.50 days to complete the period from early khalal to late khalal
stage, respectively. The fruits of Hillawi completed the period in shorter time of 12.57
days as compared to the fruits of Khadrawi those took 14.19 days to accomplish the
period from early khalal to late khalal stage. The fruits those were sprayed with ethephon
@ 6 ml/L showed intermediate effect regarding the time taken to reach the fruit at late
khalal stage in both date palm cultivars.
4.1.1.1.2b Time taken to reach the fruit at rutab stage (days)
The analyzed data presented in Figure 4.24b showed statistically significant differences
regarding the effects of ethephon treatments and cultivars while interaction between them
was found non-significant for time taken to reach the fruit at rutab stage. The fruits those
were sprayed with ethephon @ 4 ml/L took shorter time of 15.91 days to complete the
period from early khalal to rutab stage. While, fruits those were untreated took more time
of 26.41 days to accomplish the period from early khalal to rutab stage. The Hillawi fruits
completed the period from early khalal to rutab stage in shorter time (19.40 days) than the
fruits of Khadrawi those took 22.64 days to accomplish that period. The intermediary
effect was observed in fruits those were sprayed with ethephon @ 2 ml/L, 6 ml/L and by
injection @ 3 ml/bunch regarding the time taken to reach the fruit at rutab stage in both
date palm cultivars.
66
4.1.1.1.3b Rutab fruit yield per bunch (kg)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of
ethephon treatments and cultivars while their interaction showed non-significant results
for rutab fruit yield per bunch (Figure 4.25b). Ethephon treatments effectively increased
the rutab fruit yield per bunch as compared to control fruits in both date palm cultivars.
Higher rutab fruit yield (4.91 and 4.37 kg) per bunch was recorded in fruits those were
sprayed with ethephon @ 4 ml/L and 2 ml/L, respectively and these were at par with each
other. Whereas, lower rutab fruit yield of 1.67 kg per bunch was noted in untreated fruits
and these were at par with the fruits those were treated with ethephon injection @ 1
ml/bunch and 2 ml/bunch where rutab fruit yield was 1.86 and 1.96 kg per bunch,
respectively. Hillawi fruits attained more rutab fruits yield (3.27 kg) per bunch as
compared to the fruits of Khadrawi where rutab fruit yield of 2.49 kg per bunch was
noted. The fruits those were sprayed with ethephon @ 6 ml/L and by injection @ 3
ml/bunch showed intermediate effect on rutab fruit yield per bunch in both date palm
cultivars.
4.1.1.1.4b Uniform fruit ripening index (%)
Uniform fruit ripening index showed statistically significant differences at p ≤ 0.05
regarding the effects of ethephon treatments and cultivars while interaction between them
was found non-significant (Figure 4.26b). Ethephon treatments significantly increased the
uniform fruit ripening index as compared to the fruits those were untreated in both
cultivars. Maximum uniform fruit ripening indexes of 46.65 and 44.85% were noted in
fruits those were sprayed with ethephon @ 4 ml/L and 2 ml/L, respectively and these
were at par with each other. Whereas, minimum uniform fruit ripening index of 31.62%
was recorded in control fruits and these were at par with the fruits those were treated with
ethephon injection @ 1 ml/bunch, 2 ml/bunch and 3 ml/bunch where uniform fruit
ripening indexes were 31.90, 32.61 and 36.08%, respectively. The fruits of Hillawi
showed higher uniform fruit ripening index (39.46%) than the fruits of Khadrawi where
uniform fruit ripening index of 35.48% was recorded. The fruits those were sprayed with
ethephon @ 6 ml/L showed intermediate effect regarding the uniform fruit ripening index
of both date palm cultivars.
67
Figure 4.23b Effects of different ethephon concentrations (spray and injection)
on time taken (days) from early khalal to late khalal stage of
Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.24b Effects of different ethephon concentrations (spray and injection)
on time taken (days) from early khalal to rutab stage of Hillawi and
Khadrawi date palm fruit ± S.E.
0
2
4
6
8
10
12
14
16
18
20
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Tim
e t
o l
ate
kh
ala
l st
ag
e (
da
ys)
Hillawi Khadrawi
0
5
10
15
20
25
30
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Tim
e t
o l
ate
ru
tab
stg
ae (
da
ys)
Hillawi Khadrawi
68
Figure 4.25b Effects of different ethephon concentrations (spray and injection)
on rutab fruit yield per bunch (kg) of Hillawi and Khadrawi date
palm fruit ± S.E.
Figure 4.26b Effects of different ethephon concentrations (spray and injection)
on uniform fruit ripening index (%) of Hillawi and Khadrawi date
palm fruit ± S.E.
0
10
20
30
40
50
60
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Ru
tab
fru
it y
ield
bu
nch
-1 (
kg
)
Hillawi Khadrawi
0
1
2
3
4
5
6
7
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Un
ifo
rm
fru
it r
ipen
ing
in
dex (
%)
Hillawi Khadrawi
69
4.1.1.2b Fruit physical traits
4.1.1.2.1b Individual fruit weight (g)
Statistically non-significant differences (p ≥ 0.05) were found regarding the effects of
ethephon treatments and interaction while both cultivars differ significantly (4.27b). The
fruits of Hillawi cultivar attained maximum weight (7.35 g) as compared to the fruits of
Khadrawi where weight of 6.27 g was noted.
4.1.1.2.2b Fruit length (mm)
Effects of ethephon treatments and interaction showed non-significant differences (p ≥
0.05) while a significant difference were found in cultivars regarding the fruit length at
rutab stage (Figure 4.28b). Hillawi fruits achieved greater length (36.22 mm) than the
fruits of Khadrawi where fruit length of 32.36 mm was recorded.
4.1.1.2.3b Fruit width (mm)
The analyzed data presented in Figure 4.29b showed non-significant differences at p ≥
0.05 regarding the effects of ethephon treatments and interaction while a significant
difference was found in cultivars. The fruits of Khadrawi attained higher fruit width
(22.42 mm) as compared to the fruits of Hillawi where width of 18.46 mm was recorded.
4.1.1.2.4b Fruit flesh weight (g)
Fruit flesh weight at rutab stage showed non-significant differences (p ≥ 0.05) regarding
the effects of ethephon treatments and interaction while a significant difference was found
in cultivars (4.30b). Hillawi fruits showed higher flesh weight (6.41 g) than the fruits of
Khadrawi where flesh weight of 5.51 g was recorded.
4.1.1.2.5b Fruit pit weight (g)
Statistically non-significant differences were found at p ≥ 0.05 regarding the effects of
ethephon treatments and interaction while cultivars showed significant results for fruit pit
weight at rutab stage (Figure 4.31b). The fruits of Hillawi attained higher pit weight (0.94
g) as compared to the fruits of Khadrawi where pit weight of 0.76 g was noted.
70
Figure 4.27b Effects of different ethephon concentrations (spray and injection)
on individual fruit weight (g) of Hillawi and Khadrawi date palm ±
S.E.
Figure 4.28b Effects of different ethephon concentrations (spray and injection)
on fruit length (mm) of Hillawi and Khadrawi date palm ± S.E.
1
2
3
4
5
6
7
8
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
it w
eig
ht
(g)
Hillawi Khadrawi
0
5
10
15
20
25
30
35
40
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
it l
en
gth
(m
m)
Hillawi Khadrawi
71
Figure 4.29b Effects of different ethephon concentrations (spray and injection)
on fruit width (mm) of Hillawi and Khadrawi date palm ± S.E.
Figure 4.30b Effects of different ethephon concentrations (spray and injection)
on fruit flesh weight (g) of Hillawi and Khadrawi date palm fruit ±
S.E.
0
5
10
15
20
25
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
it w
idth
(m
m)
Hillawi Khadrawi
1
2
3
4
5
6
7
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
it f
lesh
weig
ht
(g)
Hillawi Khadrawi
72
Figure 4.31b Effects of different ethephon concentrations (spray and injection)
on pit weight (g) of Hillawi and Khadrawi date palm fruit ± S.E.
4.1.1.3b Fruit biochemical traits
4.1.1.3.1b Fruit moisture content (%)
The analyzed data presented in Figure 4.32b showed statistically significant differences (p
≤ 0.05) regarding the effects of ethephon treatments and cultivars while interaction
between them was found non-significant for moisture content in fruit at rutab stage. The
moisture content decreased positively as well as the fruit goes to ripening. Fruits those
were sprayed with ethephon @ 4 ml/L and 2 ml/L showed lower levels of moisture
contents (35.22 and 36.01%), respectively and these were at par with each other.
Whereas, fruits those were untreated showed higher value of moisture content (37.64%)
and these were at par with the fruits those were treated with ethephon injection @ 1
ml/bunch where moisture content of 37.14% in fruits were noted. The fruits of Hillawi
attained lower level of moisture content (36.08%) than the fruit of Khadrawi where
moisture contents of 37.00% were noted. The fruits those were sprayed with ethephon @
6 ml/L and by injection @ 3 ml/bunch showed intermediary effect on fruit moisture
content of both date palm cultivars.
4.1.1.3.2b Total soluble solids concentration (oBrix)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of
ethephon treatments and cultivars while interaction between them showed non-significant
0
0.2
0.4
0.6
0.8
1
1.2
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
it p
it w
eig
ht
(g)
Hillawi Khadrawi
73
results for total soluble solids in fruits at rutab stage (Figure 4.33b). Total soluble solids
increased positively with the progression of ripening. Higher doses of ethephon at khalal
stage decreased the level of TSS as compared to lower doses. Higher total soluble solids
of 8.03 and 7.55 oBrix were noted in fruits those were sprayed with ethephon @ 2 ml/L
and 4 ml/L, respectively and these were at par with each other. While, lower amounts of
total soluble solids (6.75 oBrix) were noted in untreated fruits and these were at par with
the fruits those were treated with ethephon injection @ 1ml/bunch, 2 ml/bunch and 3
ml/bunch and sprayed @ 6 ml/L where TSS values were 6.86, 6.90, 7.06 and 7.22 oBrix,
respectively and these were at par with each other. The Hillawi fruits attained higher total
soluble solids (7.57 oBrix) as compared to the fruits of Khadrawi where total soluble
solids of 6.81 oBrix were recorded.
4.1.1.3.3b Total titratable acidity (%)
The effects of ethephon treatments and cultivars were found significant (p ≤ 0.05) while
interaction between them showed non-significant results for total titratable acidity in
fruits at rutab stage (Figure 4.34b). The fruits those were sprayed with ethephon @ 2 ml/L
and 4 ml/L showed lower values of total titratable acidity (0.180 and 0.207%) and these
were at par with the fruits those were treated with ethephon injection @ 3 ml/bunch
where titratable acidity of 0.221% was recorded. Whereas, higher total titratable acidity
values (0.296%) were noted in control fruits and these were at par with the fruits those
were treated with ethephon injection @ 1 ml/bunch where total titratable acidity of
0.273% was recorded. The Hillawi fruits showed lower value of total titratable acidity
(0.213%) than the fruits of Khadrawi where total titratable acidity of 0.260% was noted.
The fruit sprayed with ethephon @ 6 ml/L and by injection @ 2 ml/bunch showed
intermediate effect regarding the total titratable acidity of both date palm cultivars.
4.1.1.3.4b Ascorbic acid (mg 100 g-1
)
The analyzed data presented in Figure 4.35b showed significant differences (p ≤ 0.05)
regarding the effects of ethephon treatments and cultivars while interaction between them
was found non-significant for ascorbic acid in fruit at rutab stage. Higher ascorbic acid
(1.43 and 1.32 mg 100 g-1
) was recorded in the fruits those were sprayed with ethephon
@ 2 ml/L and 4 ml/L, respectively and these were at par with each other. While, lower
ascorbic acid (1.00 mg 100 g-1
) were noted in untreated fruit and these were at par with
ethephon injection @ 1 ml, 2 ml, 3 ml/bunch and by spray @ 6 ml/L. The Hillawi fruits
attained higher ascorbic acid (1.29 mg 100 g-1
) as compared to the fruit of Khadrawi
where ascorbic acid contents of 1.06 mg 100 g-1
were noted.
74
Figure 4.32b Effects of different ethephon concentrations (spray and injection)
on moisture content (%) of Hillawi and Khadrawi date palm fruit ±
S.E.
Figure 4.33b Effects of different ethephon concentrations (spray and injection)
on total soluble solids concentration (oBrix) of Hillawi and
Khadrawi date palm fruit ± S.E.
32
33
34
35
36
37
38
39
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Mo
istu
re c
on
ten
t (%
)
Hillawi Khadrawi
0
1
2
3
4
5
6
7
8
9
10
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
TS
S (
oB
rix
)
Hillawi Khadrawi
75
Figure 4.34b Effects of different ethephon concentrations (spray and injection)
on total titratable acidity (%) of Hillawi and Khadrawi date palm
fruit ± S.E.
Figure 4.35b Effects of different ethephon concentrations (spray and injection)
on ascorbic acid (mg 100 g-1
) of Hillawi and Khadrawi date palm
fruit ± S.E.
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Acid
ity
(%
)
Hillawi Khadrawi
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Asc
orb
ic a
cid
(m
g 1
00
g-1
)
Hillawi Khadrawi
76
4.1.1.3.5b Glucose (%)
Statistically non-significant differences (p ≥ 0.05) were found regarding the effects of
ethephon treatments and interaction while both cultivars differ significantly for glucose in
fruit at rutab stage (Figure 4.36b). The application of ethephon (spray and injection) at
khalal stage did not show any response regarding the glucose in fruit of both cultivars.
The fruit of Hillawi showed higher level of glucose (20.70%) as compared to the fruit of
Khadrawi where glucose of 18.73% was recorded.
4.1.1.3.6b Fructose (%)
Fructose in fruit at rutab stage showed non-significant differences at p ≥ 0.05 regarding
the effects of ethephon treatments and interaction while a significant difference was found
in cultivars (Figure 4.37b). The application of ethephon (spray and injection) at khalal
stage did not show any positive effect on fructose in fruit of both cultivars. Hillawi fruit
achieved higher amounts of fructose (19.65%) than the fruits of Khadrawi where fructose
of 17.61% was noted.
4.1.1.3.7b Sucrose (%)
The analyzed data presented in Figure 4.38b showed statistically non-significant results (p
≥ 0.05) regarding the effects of ethephon treatments and interaction while a significant
difference was found in sucrose of both cultivars. The application of ethephon (spray and
injection) at khalal stage did not show any response regarding the sucrose in fruits of both
cultivars. The fruits of Hillawi attained higher amounts of sucrose (3.85%) than the fruits
of Khadrawi where sucrose of 2.93% was noted.
4.1.1.3.8b Reducing sugars (%)
Statistically non-significant differences were found at p ≥ 0.05 regarding the effects of
ethephon treatments and interaction while both cultivars showed significant results for
reducing sugars in fruit at rutab stage (Figure 4.39b). The application of ethephon (spray
and injection) at khalal stage did not show any response regarding the reducing sugars in
fruit of both cultivars. The Hillawi fruit achieved higher level of reducing sugars
(40.36%) as compared to the fruit of Khadrawi where reducing sugars of 36.34% were
noted.
4.1.1.3.9b Total sugars (%)
Total sugars in fruit at rutab stage showed non-significant differences (p ≥ 0.05) regarding
the effects of ethephon treatments and interaction while a significant difference was found
in cultivars (Figure 4.40b). The application of ethephon (spray and injection) at khalal
stage did not show any response regarding the total sugars in fruit of both cultivars.
77
Hillawi fruit attained higher amounts of total sugars (43.98%) as compared to the fruit of
Khadrawi where total sugars of 38.80% were noted.
Figure 4.36b Effects of different ethephon concentrations (spray and injection)
on glucose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.37b Effects of different ethephon concentrations (spray and injection)
on fructose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
0
5
10
15
20
25
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Glu
co
se (
%)
Hillawi Khadrawi
0
5
10
15
20
25
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Fru
cto
se (
%)
Hillawi Khadrawi
78
Figure 4.38b Effects of different ethephon concentrations (spray and injection)
on sucrose (%) of Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.39b Effects of different ethephon concentrations (spray and injection)
on reducing sugars (%) of Hillawi and Khadrawi date palm fruit ±
S.E.
0
1
2
3
4
5
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Su
cro
se (
%)
Hillawi Khadrawi
0
10
20
30
40
50
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
Red
ucin
g s
ug
ar (
%)
Hillawi Khadrawi
79
Figure 4.40b Effects of different ethephon concentrations (spray and injection)
on total sugars (%) of Hillawi and Khadrawi date palm fruit ± S.E.
4.1.1.4b Fruit phytonutritional traits
4.1.1.4.1b Total phenolics (mg GAE/100 g)
Total phenolics in fruit measured at rutab stage showed significant differences (p ≤ 0.05)
regarding the effects of ethephon treatments and cultivars while interaction between them
was found non-significant (Figure 4.41b). Ethephon application (spray and injection) at
khalal stage positively improved the total phenolic contents as compared to untreated fruit
of both date palm cultivars. Higher amounts of total phenolics (146.36, 143.74 and 136.43
mg GAE/100 g) were noted in fruit those treated with ethephon spray @ 2 ml/L, 4 ml/L
and 6 ml/L, respectively and these were at par with each other. Whereas, lower amounts
of total phenolics of 112.99 mg GAE/100 g were recorded in fruit those were untreated
and these were at par with the fruit those were treated with ethephon injection @ 1
ml/bunch and 2 ml/bunch where total phenolics of 114.97 and 119.39 mg GAE/100 g,
respectively were noted. The fruit of Khadrawi attained higher amounts of total phenolics
(133.87 mg GAE/100 g) as compared to the fruit of Khadrawi where total phenolics of
122.66 mg GAE/100 g were recorded.
4.1.1.4.2b Total flavonoids (mg CEQ/100 g)
Statistically non-significant differences (p ≥ 0.05) were found regarding the effects of
ethephon treatments and interaction while cultivars showed significant results for total
0
10
20
30
40
50
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
To
tal
sug
ar (
%)
Hillawi Khadrawi
80
flavonoids in fruit at rutab stage (Figure 4.42b). The application of ethephon (spray and
injection) at khalal stage did not show any response regarding the total flavonoids in fruit
of both date palm cultivars. The Hillawi fruit showed higher amounts of total flavonoids
contents (44.11 mg CEQ/100 g) as compared to the fruit of Khadrawi where total
flavonoids contents of 38.82 mg CEQ/100 g were noted.
4.1.1.4.3b Total tannins (%)
The analyzed data presented in Figure 4.43b showed significant differences at p ≤ 0.05
regarding the effects of ethephon treatments and cultivars while their interaction was
found non-significant for total tannins in fruit at rutab stage. Total tannins decreased
significantly with the progression of fruit ripening. The fruit sprayed with ethephon @ 2
ml/L and 4 ml/L showed lower levels of total tannins (0.515 and 0.546 %), respectively
and these were at par with each other. Whereas, higher amounts of total tannins of 0.897
and 0.810% were noted in fruits those were untreated and by injection @ 1 ml/bunch,
respectively and these were at par with each other. Hillawi fruits attained lower amounts
of total tannins (0.607%) than the fruit of Khadrawi where total tannins of 0.776% were
recorded. The fruits those were sprayed with ethephon @ 6 ml/L and by injection @ 3
ml/bunch showed intermediary effect on total tannins of both date palm cultivars.
4.1.1.4.4b Total antioxidants (%)
Total antioxidants activities in fruit at rutab stage showed statistically significant
differences (p ≤ 0.05) regarding the effects of ethephon treatments and cultivars while
interaction between them was found non-significant (Figure 4.44b). Higher total
antioxidants activities of 55.73 and 52.35% were noted in fruits those were sprayed with
ethephon @ 2 ml/L and 4 ml/L, respectively and these were at par with each other.
Whereas, lower total antioxidants activities of 45.92% were recorded in untreated fruits
and these were at par with the fruits those were treated with ethephon injection @ 1
ml/bunch, 2 ml/bunch, 3 ml/bunch and by foliar spray @ 6 ml/L where total antioxidants
activities of 46.33, 47.06, 47.67 and 47.86%, respectively and these were at par with each
other. The fruit of Khadrawi showed higher total antioxidants activities (51.66%) as
compared to the fruit of Hillawi where total antioxidants activities of 46.31% were
recorded.
81
Figure 4.41b Effects of different ethephon concentrations (spray and injection)
on total phenolics (mg GAE/100 g) of Hillawi and Khadrawi date
palm fruit ± S.E.
Figure 4.42b Effects of different ethephon concentrations (spray and injection)
on total flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi date
palm fruit ± S.E.
0
20
40
60
80
100
120
140
160
180
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
TP
C (
mg
GA
E/1
00
g)
Hillawi Khadrawi
0
10
20
30
40
50
60
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
TF
C (
mg
CE
Q/1
00
g)
Hillawi Khadrawi
82
Figure 4.43b Effects of different ethephon concentrations (spray and injection)
on total tannins (%) of Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.44b Effects of different ethephon concentrations (spray and injection)
on total antioxidants (%) of Hillawi and Khadrawi date palm fruit
± S.E.
0
0.2
0.4
0.6
0.8
1
1.2
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
To
tal
tan
nin
s (%
)
Hillawi Khadrawi
0
10
20
30
40
50
60
70
Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch
Foliar spray Injection
To
tal
an
tio
xid
an
ts (
%)
Hillawi Khadrawi
83
4.1.2 (a, b) Discussion
Monsoon rains at the time of fruit harvesting and/or ripening are extremely harmful and
causes heavy fruit loss in the form of rotting, fruit drop and uneven ripening and quality.
Present study therefore, was started to investigate the effects of ethephon (foliar and
injection) at final kimri and early khalal stages on the ripening acceleration and fruit
quality of Hillawi and Khadrawi date palm cultivars. Fruit maturation from final kimri to
rutab and early khalal to rutab stages indicated that application of ethephon (spray and
injection) played an important role to shorten the fruit transition period, however foliar
spray performed better as compared to injection application in both cultivars date palm
cultivars. This reduction in fruit transition period might be due to the influence of
ethylene which was released by the application of ethephon and hasten the fruit ripening
process. It is because ethylene is hydrolyzed in plant tissues (Cooke and Randall, 1968;
Warner and Leopold, 1967) and accelerates the physiological process of maturation in
fruits (Liberman, 1979). It is also reported that ethephon regulates many aspects of fruit
ripening (Szyjewicz et al., 1984; Abeles et al., 1992) and is considered as the hormone of
fruit maturation (Hartmann, 1992) as it promotes the degradation of chlorophyll that
alters the fruit texture and internal quality characters (Worku et al., 1975; Lopez et al.,
2000). Ethephon application at early fruit maturation phases accelerate the fruit ripening
processes to breakdown the cell wall which leads to tissue softening in apples (Curry,
1994). Ethephon fasten up the level of ripeness in grapevines (Han et al., 1996; Nikolaou
et al., 2003; Delgado et al., 2004), apples (Jones, 1979) and Rabbit eye blueberry (Ban et
al., 2007).
Foliar spray of ethephon applied at both fruit maturity stages (final kimri and early khalal)
gave better results as compared to injection application in both date palm cultivars.
However, ethephon application at final kimri stage was more effective as compared to
early khalal stage in both cultivars. Foliar spray of ethephon (6 ml/L and 4 ml/L) at final
kimri stage accelerated the fruit ripening period by about two weeks from final kimri to
rutab stage. Meanwhile, foliar spray of ethephon (4 ml/L and 2 ml/L) at early khalal stage
accelerated the ripening period by about 6 days form early khalal to rutab stage. Our
results are confirmed with Mougheith and Hassaballa (1979) who reported that pre-
harvest ethephon application speed up the fruit maturation period in ‘Hayany’ date palm.
These findings are also correlated with Kamal (1995) who reported that foliar application
of ethephon hasten the fruit ripening about one month in ‘Zaghloul’ and ‘Samani’ date
84
palm cultivars. Musa (2001) reported that application of ethephon accelerated the fruit
ripening period two to three folds in ‘Mishrigi Wad Khatib’ and ‘Mishrigi Wad Lagi’ date
palm cultivars. This effect of ethephon is also reported in other fruit crops such as in ber
(Zizyphus mauritiana L.) foliar application of ethephon accelerated the fruit ripening
period about 2 weeks (Bal et al., 1996), 13 to 22 days in persimmon (Kim et al., 2004)
and 8 days in fig fruits (Puech et al., 1976).
The fruit of date palm do not ripe uniformly on the tree and required more number of
pickings which ultimately increases the labor cost and is too expensive. Regarding the
effectiveness of ethephon on uniform fruit ripening in date palm, rare literature is
available. In our study foliar application of ethephon significantly increased the rutab fruit
yield per bunch and produced more uniformly ripe fruits as compared to untreated fruits
in both cultivars. More rutab fruit yield per bunch and higher uniform fruit ripening index
were noted in fruits treated with foliar spray @ 6 ml/L and 4 ml/L at final kimri and early
khalal fruit stages, respectively. The increase in rutab fruit yield per bunch and uniform
fruit ripening index were mainly due to the action of ethylene that generates from
ethephon. These findings are correlates with Ed Peter (2009) who reported that pre-
harvest spray of ethephon resulted in earlier fruit maturation and higher uniformity in
ripening with good quality composition in grapes, strawberry and cranberry fruits. These
findings are also correlated with Awad (2007) who reported that higher rutab fruit yield
per bunch or evenly ripe fruits were obtained from ethephon treated fruits in ‘Hilali’ date
palm as compared to untreated fruits. He also reported that no significant difference was
found between the foliar and injection application methods. However, in the present study
method of application showed a great variation in their response as foliar spray performed
better as compared to injection method. It is because foliar spray might have a direct
contact with fruits cuticle layer that fasten up the respiration process and fruits reached at
maturity within shorter time. Whereas, ethephon application by injection could not
showed quick and fast response due to its slow translocation from the peduncle to
individual fruit strands. It might also be possible that the whole amount of ethephon
concentrations used could not reach in proper way to the desired place.
The current findings regarding the fruit physical traits (fruit weight, fruit length, fruit
width, fruit flesh weight, fruit pit weight) showed statistically non-significant (p ≥ 0.05)
differences against ethephon application while both date palm cultivars differ
significantly. The difference in cultivars might be due to the genetic character that
responds differently to fruit physical traits.
85
Fruit moisture content is an important feature of fruit quality. Application of ethephon at
final kimri and early khalal fruit stages significantly decreased the moisture contents in
fruits of Hillawi and Khadrawi cultivars. More reduction in fruit moisture contents were
noted in fruits treated with foliar spray as compared to injection application. Foliar spray
@ 6 ml/L and 4 ml/L at final kimri and early khalal fruit stages showed more reduction in
moisture contents of both cultivars, respectively. This decline in fruit moisture contents
might be due to the progression of ripening process due the action of ethylene. The
findings of Frenkel and Hartman (2012) support our results; they reported that water
contents in potato tubers and tomato fruit were lower down due to the action of ethylene
that stimulated the onset of ripening processes, suggesting that a relationship exist
between decreased water contents and onset of ripening. They concluded that the decline
in tissue water contents induced by ethylene is strongly correlated with a decrease in
hydration efficacy of cell wall that might account for changes in tissue water contents.
Maximum total soluble solids contents in treated fruits especially where ethephon was
applied by foliar spray in both date palm cultivars during both years. It is because the
starch hydrolyzed into sugar during the progression of ripening and higher sugar contents
were noted at advanced stage of maturity or ripening (rutab). Fruit treated with foliar
spray (4 ml/L and 2 ml/L) at final kimri and early khalal stages attained higher TSS
contents in both cultivars, respectively. This increase in TSS in ethephon-treated fruits
might be due to the rise of sugar contents which depends upon the conversion of starch on
hydrolysis or it might be due to the enhanced ripening initiated by the ethylene. These
results are confirmed with the findings of (Khalifa et al., 1975; Rouhani and Bassiri,
1977) who reported that pre-harvest ethephon application efficiently improved the total
soluble solid contents in date fruits than the untreated fruits. These results were later
confirmed by (Mougheith and Hassaballa (1979; Shamshiri and Rahemi, 1999) who
reported that pre-harvest application of ethephon noticeably increased the TSS in
‘Hayany’ and Mazafati date palm cultivars. Ben-yehoshua et al. (1970) and Mougheith
and El-Banna (1974) also found similar results regarding the total soluble solids in fig
fruits. According to Sandhu et al. (1989) foliar spray of ethephon in ber (Ziziphus
mauritiana L.) fruits significantly increased the amount of total soluble solids as
compared to fruits where no ethephon was applied. Pre-harvest spray of ethephon
increased the TSS contents in table grapes (Nikolaou et al., 2003) and ‘Cripp’s Pink’
apple (Whale et al., 2008) at the time of commercial fruit harvest.
86
In ethephon treated fruits, acidity level was decreased as compared to untreated fruits.
More reduction in fruits acidity was recorded in foliar spray of ethephon as compared to
injection application. Foliar application of ethephon @ 4 ml/L and 2 ml/L at final kimri
and early fruit stages significantly decreased the level of fruit acidity, respectively. The
reduction in fruit acidity might be due to the effect of ethylene on the activity of enzymes
that promotes the fruit ripening process and lower down the acidity level (Sisler, 1984;
McGlasson, 1985; Yang, 1985). Our findings are also in line with Hashinaga and Itoo
(1985) who reported that ethephon application significantly reduced the acidity level in
‘Meiwa Kumquat’ fruits. Foliar spray of ethephon @ 4 ml/L and 2 ml/L at final kimri and
early khalal stages increased the ascorbic acid contents in treated fruits as compared to
control fruits. This is because ethephon treated fruits reached at maturity or ripening in
shorter time and fruits have less time to loss the ascorbic acid contents. These findings are
supported by various co-workers who reported that ethephon application increased the
ascorbic acid contents in different fruit crops such as cape gooseberry (Yadava et al.
2008), mango (Mann, 1985) and ‘Allahabad Safeda’ guava cultivar (Brar et al., 2012).
In the present study ethephon treatments at final kimri stage significantly increased the
accumulation of sugar contents in treated fruits while non-significant differences were
found when ethephon was applied at early khalal stage. Foliar spray of ethephon @ 4
ml/L at final kimri stage produced higher sugar contents (glucose, fructose, sucrose) as
compared to injection application in both cultivars. These results are in line with (Bal et
al., 1996; Gala et al., 2001; Singh et al., 2001; Suresh and Singh, 2003; Kulkarni et al.,
2004) they all reported that ethephon treatments significantly improved the sugar contents
in different fruits as compared to untreated fruits. The rise in sugar contents might also be
due to the onset of ripening process. However, in date fruit, no evidence is reported in the
literature which ensures that ethephon application increased the sugars contents.
Ethephon application at final kimri stage had a significant influence on the
phytonutritional composition in both date palm cultivars. More accumulation of
phytonutrients was observed in fruits treated with foliar spray as compared to injection
application. Foliar spray of ethephon @ 4 ml/L at final kimri stage showed higher amount
of total phenolics, total flavonoids and total antioxidants with lower level of total tannin
contents. However, ethephon application at early khalal stage did not show significant
variation except reduction of total tannin contents in the ethephon-treated fruit. Our
results are correlates with the findings of Lin et al. (2009) they reported that application
of ethephon generates the ethylene that plays an important role for the synthesis of
87
phenolic compounds. These findings correlates with Whale et al. (2008) who reported
that pre-harvest ethephon application significantly increased the level of phenolics and
flavonoids due to the increased concentration of cyaniding 3-galactoside in the exposed
fruit skin at commercial harvest as compared to untreated fruits. It has also been reported
that, ethephon application increased the activity of PAL in the fruit skin of apples
(Larrigaudiere et al., 1996; Li et al., 2002). A transitory exposure to ethylene can trigger
or enhance the activity of anthocyanin biosynthetic pathway (Wang and Dilley, 2001;
Awad and de Jager, 2002). Liu et al., (2013) reported that ethylene released from
ethephon significantly increased the total phenolic contents and antioxidants activities.
This increase in total phenolics might be due to the increased activity of glucose-6P
dehydrogenase (G6PDH) enzyme by the application of ethephon. Guaiacol peroxidase
(GPX) is the enzyme which is responsible for polymerization of phenolic compounds.
Higher concentration of ethephon significantly increased the GPX activity (Liu et al.,
2013). According to El-Kereamy et al. (2000) ethephon treatments enhanced the gene
expression of some enzymes that advanced the synthesis of phenolic compounds. It is
also reported that ethylene exposure in asparagus promoted the metabolism of
phenylpropanoind that leads to the accumulation of phenolic compounds and tissue
lignification (Lipton, 1990). The increase in antioxidants activities of both date palm
cultivars treated with ethephon demonstrated an increase in their nutritional value.
Ethephon treatments also build up the level of total flavonoids contents. These results are
also supported by different workers (Nikolaou et al., 2003; Lombard et al., 2004; El-
Kereamy et al., 2000); they all reported that pre-harvest ethephon application produced
higher contents of total polyphenols, flavonoids and proanthocyanidins in table grapes. In
our study total tannin contents were also decreased in fruits subjected to ethephon
treatments as compared to untreated fruits. These results are associated with the findings
of (Kato, 1990; Itamura et al., 1991; Taira et al., 1991; Park et al., 1998; Tamura et al.,
1999) they reported that higher concentration of ethephon greatly accelerated the
coagulation process of tannins in persimmon fruits due to the disappearance of
astringency and fruits become sweeter in taste. This reduction in fruit astringency might
be due to the coagulation of tannin cells into insoluble tannins.
The results of current study have an important commercial implication as pre harvest
ethephon application at final kimri stage effectively accelerated the fruit ripening period
and also improved the fruit quality composition in date palm. Foliar spray of ethephon @
4 ml/L at final kimri stage proved as the most effective to accelerate the fruit ripening
88
period by about 13 days with good fruit quality characters in both date palm cultivars.
However, ethephon application @ 2 ml/L at early khalal stage also accelerated the fruit
ripening period about 6 days but fruit quality is least affected at this stage of maturity in
both cultivars. Accelerating the fruit ripening period or shortening the period of about two
weeks between final kimri to rutab stage, growers can harvest the fruit earlier (13 days)
before the onset of peak monsoon rains. For this purpose pesticide companies should be
involved to commercialize this ethylene releasing chemical. Nonetheless, more research
is needed to investigate the response of ethephon on other commercial date palm
cultivars. The present research work suggests that more attention should be given to use
the ethephon as foliar spray at final kimri fruit maturity stage on commercial scale or at
farm level.
4.1.3 (a, b) Conclusion
In conclusion, pre-harvest spray of ethephon (4 ml/L) at final kimri stage is effective to
accelerate the fruit maturation period about 13 days, attained uniformity index of 60.46%,
rutab fruit yield (6.29 kg) per bunch and also improved the fruit quality composition in
terms of total soluble solids concentration, ascorbic acid, sugars, total phenolics, total
flavonoids and total antioxidants with decreased levels of acidity and total tannins in both
date palm cultivars. Whereas, foliar application of ethephon (2 ml/L) at early khalal stage
also accelerate the fruit maturity period about 6 days, attained uniformity index of
44.85% and rutab fruit yield (4.37 kg) per bunch while fruit quality composition is least
affected at this stage of fruit maturity in both Hillawi and Khadrawi cultivars. In
conclusion, foliar application of ethephon (4 ml/L) at final kimri stage is an effective
cultural practice to accelerate the fruit maturity period and to combat the seasonal
fluctuations in the form of monsoon rains at the time of fruit harvesting and/or ripening of
both tested date palm cultivars.
89
4.2 Study-2 Exploring the role of thinning practices on the ripening
acceleration and fruit quality of date palm
4.2.1 Results
4.2.1.1 Fruit maturity/ripening traits
4.2.1.1.1 Time taken from early kimri to final kimri stage (days)
The presented data demonstrated that strands thinning treatments and cultivars showed
significant differences (p ≤ 0.05) regarding the time taken to reach final kimri stage while
their interaction effect was found non-significant (Table 4.1). Strands thinning treatments
significantly reduced the degree days and reached the fruits earlier at maturity as
compared to fruits where no thinning was practiced. Thinning intensity @ 30% RCS +
30% STT took shorter time (95.83 days) to complete the period from early kimri to late
kimri stage that was statistically at par with thinning intensity @ 30% RCS alone which
took 97.00 days to accomplish that period. More time (107.50 days) to accomplish this
period was recorded in fruits those were without thinning treatments (control) (Table 4.1).
The fruits of Hillawi cultivar took shorter time (99.55 days) to reach from early kimri to
late kimri stage than the fruits of Khadrawi which took 102.81 days. The fruits those were
treated with thinning intensity @ 20% RCS alone and in combination with 20%
RCS+20% STT tended to have an intermediate effect regarding time taken from early
kimri to final kimri stage in both date palm cultivars.
4.2.1.1.2 Time taken from early kimri to late khalal stage (days)
Effects of strands thinning treatments and cultivars showed statistically significant
differences (p ≤ 0.05) while their interaction did not differ significantly regarding the time
taken to reach the fruit from early kimri to khalal stage (Table 4.2). Strands thinning
treatments significantly reduced the period from early kimri to late khalal stage by the
fruits as compared to no thinning treatments (control fruits). Thinning intensity @ 30%
RCS alone took shorter time of 123.25 days to complete the period from early kimri to
late khalal stage by the fruits that was statistically at par with thinning degree at the
combination of 30% RCS + 30% STT as compared to other thinning treatments.
However, maximum time (133.67 days) was noted in fruits to accomplish this period
where no thinning treatments were practiced and that was at par with thinning intensity @
20% SST alone which took 133.08 days to complete that period in both date palm
cultivars (Table 4.2). Hillawi fruits took shorter times of 126.62 days to complete the
90
period from early kimri to late khalal stage than Khadrawi fruits those took 129.69 days.
Meanwhile, strands thinning @ 20% RCS alone and in combination with 20% RCS+20%
SST showed intermediary effect on time taken from early kimri to late khalal stage of
both date palm cultivars.
4.2.1.1.3 Time taken from early kimri to rutab stage (days)
Statistical analysis showed that strands thinning treatments and cultivars differ
significantly at p ≤ 0.05 while interaction between cultivars and treatments was found
non-significant regarding time taken from early kimri to rutab stage by the fruits (Table
4.3). Thinning treatments significantly shortened the fruit transition period from early
kimri to rutab stage as compared to control fruits (no thinning). Thinning intensity @
30% RCS alone took minimum degree days (141.75 days ) to complete the period from
early kimri to rutab stage that was at par with thinning degree at combination of 30%
RCS + 30% STT which took 141.83 days to complete that period. Whereas, fruits with no
thinning treatments took 152.58 days to accomplish this period and these were
statistically similar to thinning intensity @ 20% STT and 30% STT alone which took
152.00 and 151.58 days to complete that period (Table 4.3). Fruits of Hillawi took shorter
time (144.31days) to complete the period from early kimri to rutab stage as compared to
the fruits of Khadrawi cultivar those took 149.24 days to reach from early kimri to rutab
stage. In the meanwhile, the strands thinning intensity @ 20% RCS alone and in
combination with 20% RCS+20%STT showed intermediate effect to accelerate the fruit
maturity from early kimri to rutab stage of both date palm cultivars.
4.2.1.1.4 Rutab fruit yield per bunch (kg)
Rutab fruit yield per bunch was significantly affected by strand thinning treatments,
cultivars and their interaction in both date palm cultivars (Table 4.4). Thinning treatments
significantly increased the rutab fruit yield per bunch in both cultivars than those fruits
where no thinning was practiced. Thinning degree @ 30% RCS alone achieved higher
rutab fruit yield of 5.22 kg per bunch as compared to all other treatments. Minimum rutab
fruit yield (3.00 kg) per bunch was recorded in untreated fruits where no thinning was
practiced and these were at par with strands thinning @ 20% STT alone in both date palm
cultivars (Table 4.4). Regarding the response of both cultivars, Hillawi attained higher
rutab fruit yield of 4.25 kg per bunch as compared to Khadrawi where rutab fruit yield of
3.69 kg per bunch was recorded. The strands thinning intensity @ 20% RCS alone and in
combination of 20% RCS+20% STT tended to have an intermediary effect on rutab fruit
yield per bunch of both date palm cultivars.
91
4.5 Uniform fruit ripening index (%)
Effects of strands thinning treatments and cultivars showed statistically significant
differences (p ≤ 0.05) while interaction between cultivars and treatments did not differ
significantly regarding uniform fruit ripening index (Table 4.5). Thinning treatments by
different intensities produced more uniformly ripe fruits as compared to control fruits
where no thinning was practiced in both date palm cultivars. Degree of thinning @ 30%
RCS alone showed higher uniform fruit ripening index (76.28%) as compared to all other
treatments during both years. Minimum uniform fruit ripening indexes of 34.33 and
39.79% were recorded in untreated fruits (no thinning) of both cultivars during the both
study years (Table 4.5). Hillawi cultivar showed higher uniform fruit ripening indexes
(59.09 and 56.89%) than Khadrawi where uniform fruit ripening indexes were 53.24 and
52.45% during the both years, respectively.
Table 4.1 Effects of different strands thinning intensities on time taken (days)
from early kimri to late kimri stage of Hillawi and Khadrawi date palm
fruit.
Thinning treatments Time taken from early kimri to late kimri stage (days)
Hillawi Khadrawi Mean
No thinning 105.50 109.50 107.50 A
20% RCS 97.83 101.33 99.58 C
30% RCS 95.33 98.67 97.00 DE
20% STT 103.67 107.00 105.33 B
30% STT 103.00 106.00 104.50 B
20% RCS+20%STT 97.33 99.67 98.50 CD
30%RCS+30%STT 94.17 97.50 95.83 E
Mean 99.55 B 102.81 A
LSD values Treatments= 2.01, Varieties= 1.07, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
92
Table 4.2 Effects of different strands thinning intensities on time taken (days)
from early kimri to late khalal stage of Hillawi and Khadrawi date palm
fruit.
Thinning treatments Time taken from early kimri to late khalal stage (days)
Hillawi Khadrawi Mean
No thinning 131.67 135.67 133.67 A
20% RCS 123.50 126.33 124.92 C
30% RCS 121.83 124.67 123.25 D
20% STT 131.33 134.83 133.08 AB
30% STT 130.00 134.17 132.08 B
20% RCS+20%STT 124.50 126.83 125.67 C
30%RCS+30%STT 123.50 125.33 124.42 CD
Mean 126.62 B 129.69A
LSD (P ≤ 0.05) Treatments= 1.31, Varieties= 0.70, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
Table 4.3 Effects of different strands thinning intensities on time taken (days)
from early kimri to rutab stage of Hillawi and Khadrawi date palm
fruit.
Thinning treatments Time taken from early kimri to rutab stage (days)
Hillawi Khadrawi Mean
No thinning 149.83 155.33 152.58 A
20% RCS 141.67 146.17 143.92 B
30% RCS 139.50 144.00 141.75 C
20% STT 149.33 154.67 152.00 A
30% STT 149.00 154.17 151.58 A
20% RCS+20%STT 140.83 146.67 143.75 B
30%RCS+30%STT 140.00 143.67 141.83 C
Mean 144.31 B 149.24 A
LSD (P ≤ 0.05) Treatments= 1.30, Varieties= 0.71, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
93
Table 4.4 Effects of different strands thinning intensities on rutab fruit yield (kg)
per bunch of Hillawi and Khadrawi date palm fruit.
Thinning treatments Rutab fruit yield per bunch (kg)
Hillawi Khadrawi Mean
No thinning 3.11 hi 2.90 i 3.00 F
20% RCS 4.89 c 3.73 e 4.31 C
30% RCS 5.62 a 4.81 c 5.22 A
20% STT 3.19 gh 3.06 hi 3.12 EF
30% STT 3.37 fg 3.18 gh 3.28 E
20% RCS+20%STT 4.38 d 3.56 ef 3.97 D
30%RCS+30%STT 5.19 b 4.56 d 4.87 B
Mean 4.25 A 3.69 B
LSD (P ≤ 0.05) Treatments= 0.17, Varieties= 0.09, Interaction= 0.24
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
Table 4.5 Effects of different strands thinning intensities on uniform fruit
ripening index (%) of Hillawi and Khadrawi date palm fruit.
Thinning treatments Uniform fruit ripening index (%)
Hillawi Khadrawi Mean
No thinning 39.33 34.79 37.06 E
20% RCS 64.44 59.99 62.21 C
30% RCS 80.42 72.14 76.28 A
20% STT 40.31 36.38 38.34 DE
30% STT 41.44 38.66 40.05 D
20% RCS+20%STT 64.27 58.89 61.58 C
30%RCS+30%STT 75.73 69.07 72.40 B
Mean 57.99 A 52.84 B
LSD (P ≤ 0.05) Treatments= 1.75, Varieties= 0.93, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
94
4.2.2.1 Fruit physical traits
4.2.2.1.1 Individual fruit weight (g)
Statistically significant differences were found for strands thinning treatments and
cultivars while their interaction did not differ significantly regarding individual fruit
weight at rutab stage (Table 4.6). Thinning treatments significantly increased the
individual fruit weight in both cultivars than those fruits where no thinning was practiced
during both years. A gradual increase in individual fruit weight was noted as thinning
intensity increased in both cultivars. Thinning degree at the combination of @ 30% RCS
+ 30% STT produced fruits with greater weight of 8.23 g that was statistically at par with
thinning intensity @ 30% RCS alone where fruit weight of 8.11 g was measured. Lower
individual fruit weight of 5.88 g was recorded in fruits where no thinning was performed
in both cultivars (Table 4.6). The fruits of Hillawi cultivar attained higher individual fruit
weight (7.82 g) as compared to the fruits of Khadrawi where fruit weight of 6.86 g was
measured. The strands thinning intensity @ 20% RCS alone and in combination with
20% RCS + 20%STT showed intermediary effect on individual fruit weight of both date
palm cultivars.
4.2.2.1.2 Fruit length (mm)
The analyzed data presented in Table 4.7 showed statistically significant differences for
strands thinning treatments and cultivars while their interaction was found non significant
regarding the fruit length at rutab stage. Thinning treatments significantly increased the
fruit length as compared to fruits of control (no thinning). A significant increase in fruit
lengths were observed in fruits subjected to higher degree of thinning in both cultivars.
Thinning intensity @ 30% RCS + 30% STT produced fruits with greater length of 34.53
mm and these were at par with the fruits where thinning intensity @ 30% RCS alone was
practiced with fruit length of 33.88 mm but it was greater than the fruits of all other
treatments. Minimum fruit length of 26.54 mm was noted in untreated fruits (no thinning)
of both date palm cultivars (Table 4.2.2.1.2). The fruits of Hillawi achieved greater fruit
length of 33.40 mm than the fruits of Khadrawi where fruit length of 28.03 mm was
recorded. In the meanwhile, the thinning intensity @ 20% RCS alone tended to have an
intermediate effect regarding the fruit length of both date palm cultivars.
4.2.2.1.3 Fruit width (mm)
The effects of strands thinning treatments, cultivars and their interaction were found
statistically significant regarding the fruit widths at rutab stage (Table 4.8). Thinning
treatments significantly increased the fruit width as compared to fruits where no thinning
95
was performed during both years. A gradual increase in fruit width was noted where
thinning was practiced at higher intensity than the fruits subjected to lower thinning
intensities. The interaction effect between thinning treatments and cultivars showed that
strands thinning @ 30% RCS alone produced fruits with greater width of 22.71 mm these
were statistically at par with fruit having thinning intensity @ 30% RCS + 30% STT
where fruit width of 22.32 mm was noted in Khadrawi cultivar. Whereas, minimum fruit
width of 17.10 mm was recorded in the fruits of Hillawi cultivar where no thinning was
practiced (Table 4.8). Meanwhile, regarding the response of cultivars, the fruits of
Khadrawi attained higher width of 20.78 mm than the fruits of Hillawi where fruit width
of 18.86 mm was measured. Similarly, strands thinning intensity @ 20% RCS alone and
in combination of 20% RCS + 20% STT showed intermediary effect on fruit width of
both date palm cultivars.
4.2.2.1.4 Fruit flesh weight (g)
The analyzed data presented in Table 4.9 indicated that strands thinning treatments and
cultivars showed statistically significant differences while their interaction was found
non-significant regarding fruit flesh weight at rutab stage. Strands thinning treatments
significantly increased the fruit flesh weight as compared to the fruits of no thinning
treatments. Strands thinning intensity @ 30% RCS + 30% STT produced fruits with
greater flesh weight of 7.38 g and these were at par with fruits treated with thinning
intensity @ 30% RCS alone where fruit flesh weight of 7.23 g was noted. Minimum fruit
flesh weight of 5.03 g was recorded in fruits with no thinning in both cultivars (Table
4.9). The Hillawi fruits attained higher fruit flesh weight (6.85 g) as compared to
Khadrawi fruits where flesh weight of 6.10 g was recorded. Meanwhile, the fruits with
thinning intensity @ 20% RCS alone tended to have an intermediate effect on fruit flesh
weight of both date palm cultivars.
4.2.2.1.5 Fruit pit weight (g)
Statistically non significant differences were found for strands thinning treatments and
interaction effect while both date palm cultivars differ significantly between each other
regarding the fruit pit weight at rutab stage (Table 4.10). Regarding the response of both
cultivars, greater fruit pit weight (0.97 g) was recorded in Hillawi as compared to
Khadrawi where fruit pit weight of 0.76 g was measured.
96
Table 4.6 Effects of different strands thinning intensities on individual fruit
weight (g) of Hillawi and Khadrawi date palm fruit.
Thinning treatments Individual fruit weight (g)
Hillawi Khadrawi Mean
No thinning 6.32 5.45 5.88 F
20% RCS 8.29 7.31 7.80 C
30% RCS 8.66 7.57 8.11 AB
20% STT 6.92 6.05 6.49 E
30% STT 7.29 6.47 6.88 D
20% RCS+20%STT 8.47 7.49 7.98 BC
30%RCS+30%STT 8.77 7.69 8.23 A
Mean 7.82 A 6.86 B
LSD (P ≤ 0.05) Treatments= 0.18, Varieties= 0.09, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
Table 4.7 Effects of different strands thinning intensities on fruit length (mm) of
Hillawi and Khadrawi date palm fruit.
Thinning treatments Fruit length (mm)
Hillawi Khadrawi Mean
No thinning 28.83 24.25 26.54 D
20% RCS 35.14 28.93 32.04 B
30% RCS 36.62 31.15 33.88 A
20% STT 29.79 25.19 27.49 C
30% STT 30.19 25.45 27.82 C
20% RCS+20%STT 35.81 29.56 32.69 B
30%RCS+30%STT 37.40 31.67 34.53 A
Mean 33.40 A 28.03 B
LSD (P ≤ 0.05) Treatments= 0.72, Varieties= 0.38, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
97
Table 4.8 Effects of different strand thinning intensities on fruit width (mm) of
Hillawi and Khadrawi date palm fruit.
Thinning treatments Fruit width (mm)
Hillawi Khadrawi Mean
No thinning 17.10 g 18.54 e 17.82 E
20% RCS 19.56 cd 21.42 b 20.49 B
30% RCS 19.76 cd 22.71 a 21.23 A
20% STT 17.73 f 19.29 d 18.51 D
30% STT 18.18 ef 19.56 cd 18.87 C
20% RCS+20%STT 19.72 cd 21.63 b 20.67 B
30%RCS+30%STT 19.97 c 22.32 a 21.14 A
Mean 18.86 B 20.78 A
LSD (P ≤ 0.05) Treatments= 0.35, Varieties= 0.18, Interaction= 0.50
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
Table 4.9 Effects of different strands thinning intensities on fruit flesh weight (g)
of Hillawi and Khadrawi date palm fruit.
Thinning treatments Fruit flesh weight (g)
Hillawi Khadrawi Mean
No thinning 5.38 4.67 5.03 F
20% RCS 7.27 6.51 6.89 C
30% RCS 7.65 6.81 7.23 AB
20% STT 5.97 5.35 5.66 E
30% STT 6.29 5.70 5.99 D
20% RCS+20%STT 7.53 6.72 7.13 B
30%RCS+30%STT 7.83 6.93 7.38 A
Mean 6.85 A 6.10 B
LSD (P ≤ 0.05) Treatments= 0.19, Varieties= 0.10, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
98
Table 4.10 Effects of different strands thinning intensities on fruit pit weight (g)
of Hillawi and Khadrawi date palm fruit.
Thinning treatments Fruit pit weight (g)
Hillawi Khadrawi Mean
No thinning 0.938 0.773 0.855
20% RCS 1.021 0.805 0.913
30% RCS 1.005 0.761 0.883
20% STT 0.950 0.705 0.827
30% STT 1.000 0.778 0.889
20% RCS+20%STT 0.933 0.763 0.848
30%RCS+30%STT 0.941 0.760 0.850
Mean 0.970 A 0.763 B
LSD (P ≤ 0.05) Treatments= ns, Varieties= 0.027, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
4.2.3.1 Fruit biochemical traits
4.2.3.1.1 Fruit moisture content (%)
The results presented in Table 4.11 illustrated that effects of strand thinning treatments
and cultivars were found statistically significant while their interaction did not differ
significantly regarding fruit moisture content at rutab stage. Fruit moisture decreased
progressively with the onset of fruit ripening. Thinning treatments significantly decreased
the level of moisture content in fruit as compared to non thinning fruits. Fruits thinned @
30% RCS + 30% STT showed lower levels of moisture content of 35.88% and these were
statistically at par with the fruits treated with thinning intensity @ 30% RCS alone where
moisture content of 35.91% was recorded in Hillawi cultivar. Higher level of moisture
contents of 40.85% was recorded in fruits where no thinning was practiced in Khadrawi
cultivar (Table 4.11). Whereas, the Hillawi fruits attained minimum level of moisture
content of 37.17% as compared to the fruits of Khadrawi where moisture content of
38.24% was observed. Meanwhile, the strands thinning intensity @ 20% RCS alone and
in combination of 20% RCS + 20% STT tended to have an intermediate effect on fruit
moisture content of both date palm cultivars.
4.2.3.1.2 Total soluble solids concentration (oBrix)
Strands thinning treatments and cultivars showed statistically significant results while
their interaction was found non-significant regarding the total soluble solids concentration
99
at rutab stage (Table 4.12). Thinning treatments significantly increased the TSS contents
in fruits as compared to untreated fruits (no thinning) in both date palm cultivars during
both years. Thinning intensity @ 30% RCS + 30% STT achieved higher amounts of TSS
concentration (10.95 oBrix) in fruits and these were at par with the fruits treated with
thinning intensity @ 30% RCS alone where TSS concentration 10.83 oBrix was recorded
in both date palm cultivars. However, lower amounts (7.81 oBrix) of TSS contents were
noted in control fruits subjected to no thinning in both date palm cultivars (Table 4.12).
Regarding the response of both cultivars, Hillawi fruits attained higher (10.39 oBrix) TSS
contents than Khadrawi fruits where TSS concentration of 9.24 oBrix was recorded.
Similarly, strands thinning intensity @ 20% RCS alone and in combination with 20%
RCS + 20% STT showed intermediary effect on TSS concentration of both date palm
cultivars.
4.2.3.1.3 Total titratable acidity (%)
Statistical analysis showed significant differences for strand thinning treatments and
cultivars whereas non-significant difference was found between their interactions
regarding fruit titratable acidity at rutab stage (Table 4.13). Thinning treatments
significantly decreased the acidity level in fruits as compared to fruits where no thinning
was practiced. Higher intensity of strands thinning effectively reduced the level of acidity
in fruit than lower thinning intensity. Fruit thinned @ 30% RCS + 30% STT showed
lower level of acidity (0.131%) and these were statistically at par with the fruits treated
with thinning intensity @ 30% RCS alone where level of acidity in fruits was 0.139%
while the acidity of these fruits were significantly lower as compared to fruits of other
thinning treatments in both cultivars. Maximum level (0.290%) of acidity was noted in
fruits subjected to no thinning treatments in both cultivars (Table 4.13). The fruits of
Khadrawi cultivar attained higher titratable acidity level (0.206%) than the fruits of
Hillawi where titratable acidity value of 0.165% was measured. The intermediate effect
was noted in fruits subjected to thinning intensity @ 20% RCS alone on total titratable
acidity of both date palm cultivars.
4.2.3.1.4 Ascorbic acid (mg 100 g-1
)
Ascorbic acid at rutab stage was significantly affected by strand thinning, cultivars and
their interaction in both date palm cultivars (Table 4.14). Strands thinning treatments
significantly increased the amount of ascorbic acid in fruit as compared to control fruit
(no thinning). Thinning intensity @ 30% RCS + 30% STT produced greater (1.61 mg 100
g-1
) amount of ascorbic acid contents in Hillawi fruits and these were statistically similar
100
to the fruit of Hillawi having thinning intensity @ 20% RCS + 20% STT and 30% RCS
alone where ascorbic acid values of 1.58 and 1.56 mg 100 g-1
, respectively. Whereas,
lower levels (1.02 and 1.09 mg 100 g-1
) of ascorbic acid were noted in untreated fruits (no
thinning) of Khadrawi and Hillawi cultivars, respectively (Table 4.14). The Hillawi fruit
attained higher ascorbic acid of 1.44 mg 100 g-1
as compared to Khadrawi fruits where
ascorbic acid of 1.36 mg 100 g-1
was recorded. The fruits subjected to strands thinning
intensity @ 20% RCS alone and in combination of 20% RCS + 20% STT showed
intermediate effect on ascorbic acid of both date palm cultivars.
Table 4.11 Effects of different strands thinning intensities on fruit moisture
content (%) of Hillawi and Khadrawi date palm fruit.
Thinning treatments Fruit moisture contents (%)
Hillawi Khadrawi Mean
No thinning 38.89 b 40.85 a 39.87 A
20% RCS 36.39 f 37.42 d 36.91 C
30% RCS 35.91 g 37.17 e 36.54 D
20% STT 38.41 c 38.85 b 38.63 B
30% STT 38.38 c 38.83 b 38.60 B
20% RCS+20%STT 36.37 f 37.40 d 36.88 C
30%RCS+30%STT 35.88 g 37.15 e 36.51 D
Mean 37.17 B 38.24 A
LSD (P ≤ 0.05) Treatments= 0.14, Varieties= 0.07, Interaction= 0.19
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
101
Table 4.12 Effects of different strands thinning intensities on total soluble solids
concentration (oBrix) of Hillawi and Khadrawi date palm fruit.
Thinning treatments Total soluble solids (
oBrix)
Hillawi Khadrawi Mean
No thinning 8.20 7.42 7.81 F
20% RCS 10.79 9.54 10.16 C
30% RCS 11.42 10.23 10.83 A
20% STT 9.78 8.40 9.09 E
30% STT 9.98 8.98 9.48 D
20% RCS+20%STT 10.96 9.82 10.39 B
30%RCS+30%STT 11.58 10.31 10.95 A
Mean 10.39 A 9.24 B
LSD (P ≤ 0.05) Treatments= 0.20, Varieties= 0.10, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
Table 4.13 Effects of different strands thinning intensities on total titratable
acidity (%) of Hillawi and Khadrawi date palm fruit.
Thinning treatments Total titratable acidity (%)
Hillawi Khadrawi Mean
No thinning 0.271 0.310 0.290 A
20% RCS 0.142 0.187 0.165 C
30% RCS 0.122 0.155 0.139 D
20% STT 0.189 0.239 0.214 B
30% STT 0.178 0.227 0.202 B
20% RCS+20%STT 0.140 0.173 0.156 C
30%RCS+30%STT 0.114 0.148 0.131 D
Mean 0.165 B 0.206 A
LSD (P ≤ 0.05) Treatments= 0.015, Varieties= 0.012, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
102
Table 4.14 Effects of different strands thinning intensities on ascorbic acid (mg
100 g-1
) of Hillawi and Khadrawi date palm fruit.
Thinning treatments Ascorbic acid (mg 100 g
-1)
Hillawi Khadrawi Mean
No thinning 1.09 h 1.02 h 1.05 F
20% RCS 1.46 cd 1.39 efg 1.42 D
30% RCS 1.56 ab 1.41 def 1.48 BC
20% STT 1.34 fg 1.32 g 1.33 E
30% STT 1.44 de 1.46 cde 1.45 CD
20% RCS+20%STT 1.58 ab 1.44 de 1.51 B
30%RCS+30%STT 1.61 a 1.52 bc 1.56 A
Mean 1.44 A 1.36 B
LSD (P ≤ 0.05) Treatments= 0.05, Varieties= 0.02, Interaction= 0.07
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
4.2.3.1.5 Glucose (%)
Analyzed data presented in Table 4.15 showed statistically significant results for strand
thinning treatments, cultivars and their interaction on glucose in fruit at rutab stage.
Strands thinning significantly increased the level of glucose in fruit as compared to fruits
where no thinning was practiced in both date palm cultivars. Fruits subjected to higher
degree of strand thinning showed maximum level of glucose than fruits treated with lower
thinning intensities. The interaction between thinning treatments and cultivars shows that
strands thinning intensity @ 30% RCS + 30% STT attained higher level of glucose
(30.36%) in Hillawi fruits and these were statistically at par with the fruits treated with
thinning intensity @ 30% RCS alone in Hillawi cultivar. Minimum value of glucose
(16.88%) was recorded in fruits subjected to no thinning treatments in Khadrawi cultivar
(Table 4.15). Regarding the response of both cultivars, the fruits of Hillawi attained more
glucose (26.38%) as compared to the fruits of Khadrawi where glucose of 23.67% were
recorded. The fruits subjected to strands thinning @ 20% RCS and in combination of
20% RCS + 20% STT showed intermediate effect on glucose of both date palm cultivars.
4.2.3.1.6 Fructose (%)
Statistical analysis of fructose at rutab stage showed significant differences for strands
thinning treatments, cultivars and their interaction (Table 4.16). Fruit treated with
different strand thinning intensities showed greater amounts of fructose than untreated
103
fruits (no thinning). Thinning intensity @ 30% RCS + 30% STT showed higher level of
fructose (29.40%) in the fruits of Hillawi and these were statistically at par with those
fruits treated with thinning intensity @ 30% RCS alone where fructose of 28.56% were
noted in Hillawi cultivar. Whereas, minimum level of fructose (16.10%) were noted in
control fruits of Khadrawi cultivar and these were at par with the Hillawi fruits with no
thinning (control) where fructose level of 16.86% was measured (Table 4.16). The
Hillawi fruits attained higher amounts of fructose (25.16%) than the fruits of Khadrawi
where fructose of 22.53% was recorded. In the meanwhile, the strands thinning intensity
@ 20% RCS and in combination of 20% RCS + 20% STT tended to have an intermediary
effect on fructose of both date palm cultivars.
4.2.3.1.7 Sucrose (%)
The effects of strands thinning treatments, cultivars and their interaction were found
statistically significant regarding the sucrose in fruit at rutab stage (Table 4.17). Strands
thinning treatments significantly increased the level of sucrose in fruit as compared to
fruits where no thinning was practiced in both date palm cultivars. Strands thinning
intensity @ 30% RCS + 30% STT achieved higher amounts of sucrose (6.96%) in Hillawi
fruit and these were at par with fruits treated with thinning intensity @ 30% RCS alone
where sucrose contents of 6.77% were noted in Hillawi cultivar. The minimum amounts
of sucrose (3.22%) were noted in fruits subjected to no thinning treatments in Khadrawi
date palm (Table 4.17). The fruit of Hillawi attained maximum sucrose of 5.83% as
compared to Khadrawi fruits where sucrose of 5.06% was recorded. The intermediate
effect was observed in fruits those were treated with thinning intensity @ 20% RCS alone
and in combination with 20% RCS + 20% STT regarding the sucrose of both date palm
cultivars.
4.2.3.1.8 Reducing sugars (%)
Statistical analysis in Table 4.18 showed significant differences for strand thinning
treatments, cultivars and their interaction regarding the reducing sugars in fruit at rutab
stage. Strands thinning significantly increased the reducing sugar contents in fruits as
compared to the fruit of no thinning. Strands thinning intensity @ 30% RCS + 30% STT
showed higher level of reducing sugars (59.76%) in Hillawi fruits and these were at par
with thinning intensity @ 305 RCS alone in Hillawi date palm. Whereas, lower amounts
of reducing sugars (32.99%) were recorded in control fruit of Khadrawi cultivar and these
were statistically similar to the fruits of Hillawi having no thinning where reducing sugars
of 35.12% were noted (Table 4.18). However, fruit of Hillawi attained higher level of
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reducing sugar contents (51.55%) than the fruit of Khadrawi where reducing sugars level
of 46.21% was recorded. The strands thinning @ 20% RCS alone and in combination of
20% RCS + 20% STT showed intermediate effect on reducing sugars of both date palm
cultivars.
4.2.3.1.9 Total sugars (%)
Total sugars in fruit at rutab stage were significantly affected by strand thinning
treatments, cultivars and their interaction (Table 4.19). Strands thinning treatments
effectively increased accumulation of total sugars in fruit as compared to fruits of control
(no thinning). Thinning at higher intensity showed maximum production of total sugar
contents than the fruits subjected to lower thinning intensities. Strands thinning @ 30
RCS + 30% STT achieved higher level of total sugars (66.73%) in Hillawi fruits and
these were statistically at par with the fruit having thinning intensity @ 30% RCS alone in
Hillawi fruit. The fruit subjected to no thinning treatments showed minimum level
(36.21%) of total sugars in Khadrawi date palm (Table 4.19). Hillawi fruit attained more
total sugars of 57.38% than Khadrawi fruits where total sugars of 51.27% were recorded.
The fruits subjected to strands thinning intensity @ 20% RCS alone and in combination
with 20% RCS + 20% STT tended to have an intermediary effect on total sugars of both
date palm cultivars.
Table 4.15 Effects of different strands thinning intensities on glucose (%) of
Hillawi and Khadrawi date palm fruit.
Thinning treatments Glucose contents (%)
Hillawi Khadrawi Mean
No thinning 18.25 g 16.88 h 17.56 E
20% RCS 27.66 c 25.40 de 26.53 C
30% RCS 29.72 ab 25.73 de 27.72 AB
20% STT 24.74 e 22.31 f 23.52 D
30% STT 24.93 e 23.35 f 24.14 D
20% RCS+20%STT 29.03 b 25.37 de 27.20 BC
30%RCS+30%STT 30.36 a 26.67 cd 28.52 A
Mean 26.38 A 23.67 B
LSD (P ≤ 0.05) Treatments= 0.91, Varieties= 0.49, Interaction= 1.30
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
105
Table 4.16 Effects of different strands thinning intensities on fructose (%) of
Hillawi and Khadrawi date palm fruit.
Thinning treatments Fructose contents (%)
Hillawi Khadrawi Mean
No thinning 16.86 j 16.10 j 16.48 E
20% RCS 26.60 cd 23.82 fg 25.21 C
30% RCS 28.56 ab 24.60 ef 26.58 AB
20% STT 23.06 gh 21.42 i 22.24 D
30% STT 23.75 fg 22.21 hi 22.98 D
20% RCS+20%STT 27.90 bc 24.04 fg 25.97 BC
30%RCS+30%STT 29.40 a 25.54 de 27.47 A
Mean 25.16 A 22.53 B
LSD (P ≤ 0.05) Treatments= 0.94, Varieties= 0.50, Interaction= 1.33
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
Table 4.17 Effects of different strands thinning intensities on sucrose (%) of
Hillawi and Khadrawi date palm fruit.
Thinning treatments Sucrose contents (%)
Hillawi Khadrawi Mean
No thinning 3.91 j 3.22 k 3.56 E
20% RCS 6.21 bc 5.16 gh 5.68 C
30% RCS 6.77 a 5.82 de 6.29 A
20% STT 5.15 gh 4.77 i 4.96 D
30% STT 5.42 fg 4.89 hi 5.16 D
20% RCS+20%STT 6.38 b 5.54 ef 5.96 B
30%RCS+30%STT 6.96 a 5.99 cd 6.48 A
Mean 5.83 A 5.06 B
LSD (P ≤ 0.05) Treatments= 0.20, Varieties= 0.11, Interaction= 0.29
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
106
Table 4.18 Effects of different strands thinning intensities on reducing sugars (%)
of Hillawi and Khadrawi date palm fruit.
Thinning treatments Reducing sugar contents (%)
Hillawi Khadrawi Mean
No thinning 35.12 h 32.99 h 34.05 E
20% RCS 54.27 c 49.22 e 51.74 C
30% RCS 58.28 ab 50.34 de 54.31 AB
20% STT 47.81 ef 43.73 g 45.77 D
30% STT 48.68 e 45.57 fg 47.12 D
20% RCS+20%STT 56.93 b 49.42 e 53.17 BC
30%RCS+30%STT 59.76 a 52.22 cd 55.99 A
Mean 51.55 A 46.21 B
LSD (P ≤ 0.05) Treatments= 1.84, Varieties= 0.98, Interaction= 2.60
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
Table 4.19 Effects of different strands thinning intensities on total sugars (%) of
Hillawi and Khadrawi date palm fruit.
Thinning treatments Total sugar contents (%)
Hillawi Khadrawi Mean
No thinning 39.03 i 36.21 j 37.62 E
20% RCS 60.48 c 54.38 ef 57.43 C
30% RCS 65.06 ab 56.16 de 60.61 AB
20% STT 52.96 fg 48.50 h 50.73 D
30% STT 54.11 ef 50.46 gh 52.29 D
20% RCS+20%STT 63.31 b 54.97 ef 59.14 BC
30%RCS+30%STT 66.73 a 58.22 cd 62.47 A
Mean 57.38 A 51.27 B
LSD (P ≤ 0.05) Treatments= 1.93, Varieties= 1.03, Interaction= 2.72
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
107
4.2.4.1 Fruit phytonutritional traits
4.2.4.1.1 Total phenolics (mg GAE/100 g)
Total phenolics in fruit at rutab stage were significantly affected by strands thinning
treatments and cultivars while their interaction was non-significant (Table 4.20). Strands
thinning significantly increased the level of total phenolics in treated fruits as compared
to fruits of control (without thinning) in both date palm cultivars. Strands thinning
intensity @ 30% RCS + 30% STT showed higher level of total phenolics (179.86 mg
GAE/100 g) in fruits and these were statistically at par with the fruits having thinning
intensity @ 30% RCS alone where TPC of 176.73 mg GAE/100 g was recorded.
Whereas, lower amounts of TPC (114.64 mg GAE/100 g) were noted in untreated fruits
(no thinning) (Table 4.20). The fruit of Khadrawi showed more TPC contents (162.87 mg
GAE/100 g) as compared to the Khadrawi fruits where TPC of 154.17 mg GAE/100 g
was measured. The fruits subjected to strands thinning intensity @ 20% RCS alone and in
combination of 20% RCS + 20% STT tended to have intermediate effect on TPC of both
date palm cultivars.
4.2.4.1.2 Total flavonoids (mg CEQ/100 g)
The analyzed data regarding total flavonoids at rutab stage showed statistically significant
differences but non-significant for their interaction (Table 4.21). Strands thinning
significantly increased the TFC in fruit as compared to untreated fruits (no thinning) in
both cultivars. Strands thinning intensity @ 30% RCS + 30% STT showed maximum
amounts of TFC (57.81 mg CEQ/100 g) in fruits these were at par to the fruits with
thinning intensity @ 30% RCS alone where TFC of 56.50 mg CEQ/100 g were recorded.
Whereas, lower level of TFC (21.82 mg GAE/100 g) were noted in fruits where no
thinning was practiced (Table 4.21). Regarding the response of both cultivars, Hillawi
fruits attained higher amounts of TFC (49.60 mg CEQ/100 g) as compared to the fruits of
Khadrawi where TFC of 44.26 mg CEQ/100 g was measured. Meanwhile, the strands
thinning intensity @ 20% RCS alone and in combination of 20% RCS + 20% STT
showed intermediary effect on TFC of both date palm cultivars.
4.2.4.1.3 Total tannins (%)
The effects of strands thinning treatments and cultivars were found statistically significant
while their interaction showed non-significant differences regarding the total tannins in
fruits at rutab stage (Table 4.22). Total tannins decreased rapidly with the progression of
fruit ripening. Strands thinning treatments effectively reduced the level of total tannin
108
contents in fruit as compared to the fruits subjected to no thinning in both date palm
cultivars. Strands thinning intensity @ 30% RCS + 30% STT showed lower amounts of
total tannins (0.237%) in fruit and these were at par with the fruits having thinning
intensity @ 30% RCS alone where total tannins of 0.250% were noted. Maximum values
of total tannins (0.655%) were noted in fruit subjected to no thinning treatments (Table
4.22). The fruit of Hillawi attained lower (0.362%) total tannin contents as compared to
the fruits of Khadrawi cultivar where total tannins of 0.393% were recorded. The strands
thinning intensity @ 20% RCS alone and in combination of 20% RCS + 20% STT
showed intermediate effect regarding the total tannins in both date palm cultivars.
4.2.4.1.4 Total antioxidants (%)
Total antioxidants in fruits at rutab stage were significantly affected by strands thinning
treatments and cultivars while interaction between them was found non-significant (Table
4.23). Strands thinning efficiently increased the total antioxidants activities in fruits as
compared to fruits where no thinning was performed. Strands thinning intensity @ 30%
RCS + 30% STT showed higher antioxidants (70.76%) in fruits and these were at par
with the fruits having thinning intensity @ 30% RCS alone where total antioxidants
activities of 70.10% were measured. Whereas, lower antioxidants activities (38.33%)
were recorded in untreated fruits (no thinning) (Table 4.23). The Khadrawi fruits attained
higher antioxidants activities (61.64%) as compared to Khadrawi fruits where
antioxidants activities of 57.99% were recorded. In the meanwhile, the fruits subjected to
strands thinning intensity @ 20% RCS alone and in combination of 20% RCS + 20%
STT tended to have intermediate effect on total antioxidants activities of both date palm
cultivars.
109
Table 4.20 Effects of different strands thinning intensities on total phenolics (mg
GAE/100 g) of Hillawi and Khadrawi date palm fruit.
Thinning treatments Total phenolics (mg GAE/100 g)
Hillawi Khadrawi Mean
No thinning 111.20 118.07 114.64 E
20% RCS 159.84 166.68 163.26 B
30% RCS 171.70 181.76 176.73 A
20% STT 149.21 155.03 152.12 D
30% STT 153.36 162.07 157.71 C
20% RCS+20%STT 161.27 169.41 165.34 B
30%RCS+30%STT 172.64 187.07 179.86 A
Mean 154.17 B 162.87 A
LSD (P ≤ 0.05) Treatments= 3.31, Varieties= 1.77, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
Table 4.21 Effects of different strands thinning intensities on total flavonoids (mg
CEQ/100 g) of Hillawi and Khadrawi date palm fruit.
Thinning treatments Total flavonoids (mg CEQ/100 g)
Hillawi Khadrawi Mean
No thinning 24.77 18.88 21.82 D
20% RCS 52.03 47.99 50.01 B
30% RCS 60.27 52.73 56.50 A
20% STT 46.28 42.42 44.35 C
30% STT 50.40 45.87 48.14 B
20% RCS+20%STT 51.81 47.93 49.87 B
30%RCS+30%STT 61.64 53.99 57.81 A
Mean 49.60 A 44.26 B
LSD (P ≤ 0.05) Treatments= 2.09, Varieties= 1.11, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
110
Table 4.22 Effects of different strands thinning intensities on total tannins (%) of
Hillawi and Khadrawi date palm fruit.
Thinning treatments Total tannin contents (%)
Hillawi Khadrawi Mean
No thinning 0.623 0.686 0.655 A
20% RCS 0.288 0.308 0.298 D
30% RCS 0.231 0.270 0.250 E
20% STT 0.461 0.493 0.477 B
30% STT 0.435 0.446 0.440 C
20% RCS+20%STT 0.280 0.295 0.287 D
30%RCS+30%STT 0.218 0.256 0.237 E
Mean 0.362 B 0.393 A
LSD (P ≤ 0.05) Treatments= 0.028, Varieties= 0.015, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
Table 4.23 Effects of different strands thinning intensities on total antioxidants
(%) of Hillawi and Khadrawi date palm fruit.
Thinning treatments Total antioxidants activities (%)
Hillawi Khadrawi Mean
No thinning 36.95 39.72 38.33 F
20% RCS 59.99 64.08 62.04 C
30% RCS 68.43 71.77 70.10 A
20% STT 53.53 57.26 55.39 E
30% STT 56.43 58.78 57.60 D
20% RCS+20%STT 61.91 67.10 64.50 B
30%RCS+30%STT 68.66 72.74 70.70 A
Mean 57.99 B 61.64 A
LSD (P ≤ 0.05) Treatments= 1.29, Varieties= 0.69, Interaction= ns
RCS= Removal of central strands, STT= Shortening of terminal tips
Means sharing same case letter for main effects and interaction, do not differ significantly
at 5% probability level.
111
4.2.2 Discussion
Fruit quality is a chief component to attain maximum economic return and develop
healthy relationship between supply and demand. In spite of profuse date’s production in
the country, growers do not pay any concentration for improving the fruit physical and
quality characters and fetch low market prices. Uneven fruit maturity/ripening in date
palm are a common problem which results poor quality fruits with less economic return.
Fruit thinning is an important managerial approach to achieve constant yields of high
quality fruits with respect to fruit size and nutrient contents (Lippert and Blanke, 2004).
Therefore, present study was carried out to investigate the effects of strand thinning to
accelerate the fruit maturity and quality composition in date fruit. Fruit maturation period
from early kimri to late kimri, late khalal and rutab stages indicated that strand thinning
treatments play an important role to accelerate the fruit maturation period in Hillawi and
Khadrawi date palm cultivars. This acceleration in fruit maturation period might be due to
the accumulation and proper supply of assimilates and photosynthates to remaining
individual fruits by thinning treatments. Fruit thinning is effective after four to six weeks
of full bloom because of less competition for food among young fruits and to ensure a
proper supply of assimilates and photosynthates right from the moment of fruit formation
(Di Marco et al., 1992). Cluster thinning has an important role in plants to induct
physiological adjustments by improving the kinetics of fruits maturation. It is because
thinning improves the sanitary conditions under the canopy and allows more
enlightenment and fresh air penetration in the remaining fruit clusters (Smithyman et al.,
1998).
In the current study, strands thinning significantly reduced the fruits maturation period as
compared to fruits where no thinning was applied in both date palm cultivars. Fruits
treated with strands thinning took shorter time to complete the period from early kimri to
late kimri, early kimri to late khalal and early kimri to rutab stages as compared to un-
thinned fruits in both Hillawi and Khadrawi date palm cultivars. Strands thinning
intensity @ 30% RCS alone and 30% RCS + 30% STT accelerated the fruit ripening
processes and shortened the period by about 10 days from early kimri to rutab stage.
These results are correlated with Myers et al., (1993) who reported that fruit thinning
significantly accelerated the fruit maturity period in peaches. Khademi (1998) reported
that thinning of central strands at pollination time is much more effective in accelerating
the ripening time of ‘Kabkaab’ dates. Strands thinning also increased the rutab fruit yield
112
per bunch and produced more uniformly ripe fruits than the fruits subjected to no
thinning. Strands thinning intensity @ 30% RCS + 30% STT and 30% RCS alone showed
higher rutab fruit yield per bunch and greater uniform fruit ripening index in both the date
palm cultivars. This might be due to the involvement of more light penetration and air
circulation within the fruit bunches that leads to fast and uniformly ripe fruits. It might
also be possible that thinned fruits received sufficient nutrients and water from the main
stem or bunches due to less competition among the remaining fruit and develop their
physiological and chemical constituents of maturation as quickly and uniformly as
compared to un-thinned fruits. However, in date palm no documented evidence is
available which explain this phenomenon but these results are correlates with Bonora et
al. (2013) they supports this explanation and concluded that balanced fruits density in
nectarine trees produced fruits with high homogeneity in terms of growth, maturation and
soluble solids contents.
Strands thinning treatments significantly affected the fruits physical characters in both
date palm cultivars as compared to no thinning fruits in both date palm cultivars. Strands
thinning intensity @ 30% RCS + 30% STT and 30% RCS alone showed higher fruit
weight, fruit length, fruit width and flesh weight in both date palm cultivars. The reasons
are same as explained above but some others can also strengthen these reasons. The
improvement in fruits growth physical parameters could be due to the abundance
accumulation of photosynthates to the remaining fruit strands (Ali-Dinar et al., 2002;
Soliman et al., 2011; Soliman and Harhash, 2012). It is because that initial fruits
development/pericarp growth is regulated by cell division and cell enlargement and also
these processes dependent on photosynthesis (Hole and Scott, 1981). Sun light exposure
is also important to regulate the metabolism of carbon and assimilates in young growing
fruits. In contrast, control fruits (un-thinned) had less light exposure due to high density
that reduced the sink strength and fruits could not develop their growth properly and
uniformly. It is reported that regulation of fruits growth and development are dependent
on light which influenced the activity of phytohormones (Coombe, 1973). Our results are
correlated with the findings of Goffinet et al. (1995) they reported that fruit thinning
reduced the crop load and remaining fruits showed increased fruit size. Thinning reduced
the number of fruit per shoot/tree while the remaining fruits increase their dimensions due
to proper light and photosynthesis as found in mango (Mendoza and Wills 1984), pear
(Kappel and Neilsen 1994) and apple (Morgan et al. 1984). These findings are in line
113
with Costa and Vizzotto (2000) who reported that thinning of fruits in peaches reduced
the competition between fruits and vegetative sinks and enhance the fruit size.
Strands thinning treatments efficiently improved the biochemical characters in fruits as
compared to un-thinned fruits in both cultivars. Strands thinning intensity @ 30% RCS
alone and 30% RCS + 30% STT showed higher TSS, ascorbic acid, sugars accumulation
and decreased the level of acidity as compared to no thinning. The reasons are same as
reported in earlier paragraphs but some coworkers also support these reasons. Fruits
subjected to strand thinning treatments showed lower level of moisture contents than
fruits without thinning. These results are correlated with Blanke and Leyhe (1987) who
reported that fruits exposed to more sun-light showed higher transpiration rate as
compared to control fruits (Blanke and Leyhe, 1987). The increase in TSS, ascorbic acid
and decrease in acidity are supported by different coworkers (Mostafa and El-Akkad,
2011; Iizadi et al., 2010; Soliman et al., 2011). More sugars accomulation in thinned
fruits are also supported are in line with Brown and Coombe (1985) and (Crippen and
Morrison, 1986) who reported that light exposure regulates the activity of invertase
enzyme which is responsible for sugars accumulation in grape berries.
Fruit phytonutrients (total phenolics, total flavonoids and total antioxidants) were
significantly improved and tannin contents were decreased by strand thinning treatments
in both date palm cultivars. Strands thinning @ 30% RCS alone and 30% RCS + 30%
STT showed higher levels of phytonutrients in fruits at rutab stage than no thinning
treatments. The greater improvement in quality of total phenolics, total flavonoids, total
antioxidants and reduction of total tannins in thinning treatments confirmed our previous
explanation as reported in physical and chemical parameters. The main reason is that
more exposure of light due to less fruits density; it is because light plays an important role
in processes which are responsible for the accumulation of anthocyanins and phenolic
compounds (Wicks and Kliewer 1983, Dokoozlian and Kliewer 1996). These findings
were supported by Bubola et al. (2011) and Profio et al. (2012) who reported that cluster
thinning significantly increased the accumulation of phenolics in grape berries. On the
other hand, un-thinned fruits could not attain proper return due to less availability of light
or air circulation that affects the rate of photosynthetic carbon assimilation rate (Morrison
and Noble, 1990).
The findings of the present study have an important commercial implication that strands
thinning at early fruit stages (4 weeks after pollination) accelerated the fruits maturation
processes and reduced the period about 10 days and also improved the fruit physical,
114
chemical and phytonutritional composition in both date palm cultivars. Strands thinning
intensity @ 30% RCS alone and 30% RCS + 30% STT effectively reduced the fruit
maturity cycle and improved the fruit quality in Hillawi and Khadrawi cultivars which is
confirmed from this comprehensive study. These findings could be helpful in achieving
the desired goal. Growers can minimize the date fruit losses occurred due to monsoon
rains by harvesting the fruit 10 days earlier by adopting strands thinning technologies.
Moreover, large fruit size, uniformity in ripening and good quality fruits can increase the
return.
4.2.3 Conclusion
In conclusion, strands thinning at early kimri stage reduced the period of 10 days beyond
of control fruit (without thinning) from kimri to rutab stage by accelerating the maturation
processes. Strands thinning intensity (30% RCS alone) resulted in higher yield of 5.22 kg
per bunch and more uniformly ripe fruit (76.28%) at rutab stage in both date palm
cultivars during both years. The total soluble solids concentration, ascorbic acid, sugars
(glucose, fructose, and sucrose), total phenolics, total flavonoids and total antioxidants
were significantly improved while titratable acidity and total tannin contents were
decreased in thinned fruit. Strands thinning intensity @ 30% RCS alone proved best
thinning treatment for obtaining the desired fruit quality traits as compared to other
thinning intensities. Meanwhile, the fruits subjected to strands thinning intensity (20%
RCS alone) tended to have an intermediate effect on all the measured parameters of both
date palm cultivars.
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4.3. Study-3 Ripening and quality assessment of date palm fruit by
the influence of hot water treatment.
4.3.1 Results
4.3.1.1 Fruit physical traits
4.3.1.1.1 Time taken to reach the fruit at tamar stage (days)
The presented data in Figure 4.45 showed statistically significant differences (p ≤ 0.05)
regarding the effects of hot water treatments and cultivars while interaction between them
was found non-significant for time taken to reach at tamar stage by the fruit. The fruits
those were immersed in hot water for longer duration reached earlier at tamar stage as
compared to the fruits of shorter duration. Hot water treatments exposure for 7 min at
65oC took shorter time of 6.16 and 7.83 days to reach at tamar stage by the fruits. While,
more time of 11.66 and 11.33 days to reach the fruits at tamar stage were noted in
untreated fruits and HWT for 1 min at 65oC, respectively and these were at par with each
other. The fruits of Hillawi took shorter time of 8.86 days to reach at tamar stage as
compared to the fruits of Khadrawi those took 9.66 days to accomplish that period. The
fruits subjected to 5 min hot water immersion showed intermediate effect regarding time
taken to reach the fruit at tamar stage in both date palm cultivars.
4.3.1.1.2 Uniform fruit ripening index (%)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of hot
water treatments and interaction while cultivars showed non-significant results for
uniform fruit ripening index (Figure 4.46). Fruit immersed in higher temperature of 7 min
at 65oC did not show uniformity in fruit ripening as compared to lower temperatures. The
higher uniform fruit ripening index of 69.00% was noted in fruits those were treated with
hot water with an exposure time of 5 min at 65oC and minimum uniform fruit ripening
index of 11.25% was recorded in untreated fruits. The interaction between hot water
treatments and cultivars showed that maximum uniform fruit ripening indexes of 81.66
and 73.33% were noted in fruits those were treated with hot water with an exposure time
of 5 and 3 min at 65oC in Hillawi and Khadrawi cultivars, respectively and these were at
par with each other. Whereas, minimum uniform fruit ripening indexes of 10.70 and
11.81% were recorded in untreated fruits of Hillawi and Khadrawi and these were at par
with the fruits those were treated with hot water with an exposure time of 7 min and 1
min at 65oC in Hillawi and Khadrawi fruits where uniform fruit ripening indexes were
116
16.30 and 20.88%, respectively and these were at par with each other. The hot water
immersion for 3 min at 65oC tended to have an intermediate effect on uniform fruit
ripening of both date palm cultivars.
4.3.1.1.3 Fruit weight loss (%)
Effects of hot water treatments and cultivars were found statistically significant (p ≤ 0.05)
while their interaction showed non-significant difference regarding the fruit weight loss at
tamar stage (Figure 4.47). Fruit weight loss increased positively at higher temperature as
compared to lower ones. Hot water treatment with an exposure time of 7 min at 65oC
showed higher loss in weight of 22.87% and minimum loss in weight of 11.73% was
noted in untreated fruits and these were at par with the fruits those were treated with hot
water with an exposure times of 1 min and 3 min at 65oC where losses in weights were
12.96 and 14.51% in fruits, respectively. The fruits of Khadrawi showed minimum loss in
weight (14.26%) than the fruits of Hillawi where loss in weight of 17.35% was recorded.
The fruits subjected to hot water immersion for 1 and 3 min at 65oC showed intermediate
effect regarding the fruit weight loss of both date palm cultivars.
4.3.1.1.4 Fruit moisture content (%)
Moisture content in fruit at tamar stage showed statistically significant differences (p ≤
0.05) regarding the effects of hot water treatments, cultivars and interaction between them
(Figure 4.48). Higher temperature effectively decreased the moisture contents in fruits as
compared to lower temperature. Fruits those were immersed in hot water with an
exposure time of 7 min at 65oC showed lower amounts of moisture content (16.97%) in
fruits and higher level of moisture contents of 29.73% was noted in fruits those were
untreated. The fruits of Khadrawi showed higher level of moisture contents (26.63%) as
compared to the fruits of Hillawi where moisture content was 21.77%. The interaction
between hot water treatments and cultivars showed that fruits those were immersed in hot
water with an exposure time of 7 min at 65oC showed lower level of moisture content
(11.32%). Whereas, fruits those were untreated and dipped in hot water for 1 min at 65oC
showed higher levels of moisture contents (30.66, 28.81 and 28.36%) in Khadrawi,
Hillawi and Khadrawi, respectively and these were at par with each other. The
intermediate effect on moisture content was recorded in fruits those were immersed in hot
water for 3 min at 65oC in both date palm cultivars.
4.3.1.1.5 Fruit flesh weight (g)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of hot
water treatments and cultivars while interaction between them showed non-significant
117
results for fruit flesh weight at tamar stage (Figure 4.49). Higher temperature significantly
decreased the fruit flesh weight as compared to fruits those were immersed in low
temperature. Lower values of flesh weights (4.34 and 4.66 g) were recorded in fruits
those were immersed in hot water with an exposure times of 7 min and 5 min at 65oC,
respectively and these were at par with each other. While, higher flesh weight of 5.55 g
was noted in untreated fruits and these were at par with the fruits those were dipped in hot
water for 1 min and 3 min where flesh weights were 5.44 and 5.14 g in fruits, respectively
and these were at par with each other. Khadrawi fruits showed maximum flesh weight
(5.39 g) as compared to the fruits of Hillawi where flesh weight of 4.66 g was noted.
4.3.1.1.6 Fruit pit weight (g)
The analysed data presented in Figure 4.50 showed significant differences (p ≤ 0.05)
regarding the effects of hot water treatments while cultivars and interaction between them
was found non-significant for fruit pit weight. Fruits those were immersed in higher
temperature of 7 min at 65oC effectively decreased the pit weight as compared to fruits
those were immersed in low temperature. Higher pit weight of 0.73 g was noted in fruits
those were untreated and these were at par with the fruits those were immersed in hot
water for 1 min and 3 min at 65oC where pit weights were 0.70 and 0.65 g, respectively
and these were at par with each other. Whereas, lower pit weights (0.54 and 0.61 g) were
recorded in fruits those were treated with hot water with an exposure times of 7 min and 5
min at 65oC, respectively and these were at par with each other.
118
Figure 4.45 Effects of hot water treatments at 65oC on time taken to tamar stage
(days) of Hillawi and Khadrawi date palm fruit ±S.E.
Figure 4.46 Effects of hot water treatments at 65oC on uniform fruit ripening
index (%) of Hillawi and Khadrawi date palm fruit ± S.E.
0
2
4
6
8
10
12
14T
ime t
o t
am
er s
tag
e (
da
ys)
Duration of HWT at 65oC
Hillawi Khadrawi
0
10
20
30
40
50
60
70
80
90
Un
ifo
rm
rip
en
ing
in
dex (
%)
Duration of HWT at 65oC
Hillawi Khadrawi
119
Figure 4.47 Effects of hot water treatments at 65oC on fruit weight loss (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.48 Effects of hot water treatments at 65oC on moisture content (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
0
5
10
15
20
25
30W
eig
ht
loss
(%
)
Hillawi Khadrawi
0
5
10
15
20
25
30
35
Mo
istu
re c
on
ten
t (%
)
Duration of HWT at 65oC
Hillawi Khadrawi
120
Figure 4.49 Effects of hot water treatments at 65oC on fruit flesh weight (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.50 Effects of hot water treatments at 65oC on pit weight (%) of Hillawi
and Khadrawi date palm fruit ± S.E.
0
1
2
3
4
5
6
7F
ru
it f
lesh
weig
ht
(g)
Duration of HWT at 65oC
Hillawi Khadrawi
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Fru
it p
it w
eig
ht
(g)
Duration of HWT at 65oC
Hillawi Khadrawi
121
Control (cv. Hillawi) HWT for 1 min (cv. Hillawi)
HWT for 3 min (cv. Hillawi) HWT for 5 min (cv. Hillawi)
HWT for 7 min (cv. Hillawi)
Slide-4.1: Effects of hot water treatment (HWT) on the ripening behaviour of
Hillawi fruit under ambient conditions.
122
Control (cv. Khadrawi) HWT for 1 min (cv. Khadrawi)
HWT for 3 min (cv. Khadrawi) HWT for 5 min (cv. Khadrawi)
HWT for 7 min (cv. Khadrawi)
Slide-4.2: Effects of hot water treatment (HWT) on the ripening behaviour of
Khadrawi fruit under ambient conditions.
123
4.3.1.2 Fruit biochemical traits
4.3.1.2.1 Total soluble solids concentration (oBrix)
Statistically significant differences (p ≤ 0.05) were found regarding the effects of hot
water treatments, cultivars and their interaction on total soluble solids concentration in
fruit at tamar stage (Figure 4.51). High degree of temperature for 7 min at 65oC
progressively lowers down the TSS concentration than low degree of temperature. Higher
amounts of total soluble solids concentration of 9.75 oBrix were noted in fruits those were
immersed in hot water for 3 min at 65oC while fruits those were untreated showed lower
amounts of total soluble solids (4.13 oBrix). The fruits of Hillawi attained higher level of
total soluble solids concentration (7.56 oBrix) as compared to the fruits of Khadrawi
where total soluble solids contents of 7.03 oBrix were recorded. The interaction hot water
treatments and cultivars showed that higher level of total soluble solids contents (11.77
oBrix) were recorded in the Hillawi fruits those were immersed in hot water for 3 min at
65oC. Whereas, lower amounts of total soluble solids concentration of 3.91, 4.36 and 4.69
oBrix were recorded in the fruits of Khadrawi, Hillawi and Khadrawi those were untreated
and immersed in hot water for 1 min at 65oC, respectively and these were at par with each
other. The fruit subjected to hot water immersion for 1 and 5 min at 65oC showed
intermediate effect on TSS concentration of both date palm cultivars.
4.3.1.2.2 Total titratable acidity (%)
The analysed data presented in Figure 4.52 showed statistically significant results (p ≤
0.05) regarding the effects of hot water treatments, cultivars and their interaction on total
titratable acidity in fruits at tamar stage. Lower levels of total titratable acidity of 0.144
and 0.147% were recorded in fruits those were treated with hot water for 5 min at 65oC
while higher level of total titratable acidity of 0.183% was noted in fruits those were
untreated. The Hillawi fruits showed lower level of total titratable acidity (0.144%) than
the fruits of Khadrawi where total titratable acidity of 0.174% was noted. The interaction
between hot water treatments and cultivars showed that the fruits of Hillawi those were
immersed in hot water for 3 min, 1 min and 5 min showed lower values of total titratable
acidity (0.123, 0.138 and 0.142%), respectively and these were at par with each other.
Whereas, higher amounts of total titratable of 0.205 and 0.195% were noted in the fruits
of Khadrawi cultivar those were untreated and immersed in hot water for 1 min at 65oC,
respectively and these were at par with each other.
124
4.3.1.2.3 Ascorbic acid (mg 100 g-1
)
Ascorbic acid contents in fruit at tamar stage showed significant differences at p ≤ 0.05
regarding the effects of hot water treatments, cultivars and interaction between them
(Figure 4.53). Maximum amounts of ascorbic acid (0.882 and 0.826 mg 100 g-1
) were
noted in fruits those were untreated and immersed in hot water for 1 min at 65oC,
respectively and these were at par with each other. While, minimum ascorbic acid of
0.741, 0.749 and 0.779 mg 100 g-1
were recorded in fruits those were treated with hot
water for 3 min, 5 min and 7 min at 65oC, respectively and these were at par with each
other. The fruit of Hillawi showed lower amounts of ascorbic acid (0.757 mg 100 g-1
) as
compared to the fruits of Khadrawi where ascorbic acid of 0.834 mg 100 g-1
was
recorded. The interaction between hot water treatments and cultivars showed that the fruit
of Khadrawi cultivar those were untreated and immersed in hot water for 1 min at 65oC
showed higher levels of ascorbic acid (0.944 and 0.909 mg 100 g-1
), respectively and
these were at par with each other. While, lower values of ascorbic acid (0.665, 0.733 and
0.744 mg 100 g-1
) were noted in the fruit of Hillawi, Khadrawi and Hillawi those were
treated with hot water for 3 min, 5 min and 1 min at 65oC, respectively and these were at
par with each other.
Figure 4.51 Effects of hot water treatments at 65oC on total soluble solids
concentration (oBrix) of Hillawi and Khadrawi date palm fruit ± S.E.
0
2
4
6
8
10
12
14
TS
S (
oB
rix)
Duration of HWT at 65oC
Hillawi Khadrawi
125
Figure 4.52 Effects of hot water treatments at 65oC on titratable acidity (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.53 Effects of hot water treatments at 65oC on ascorbic acid (mg 100 g
-1) of
Hillawi and Khadrawi date palm fruit ± S.E.
0
0.05
0.1
0.15
0.2
0.25A
cid
ity
(%
)
Duration of HWT at 65oC
Hillawi Khadrawi
0
0.2
0.4
0.6
0.8
1
1.2
Asc
orb
ic a
cid
(m
g 1
00
g-1
)
Duration of HWT at 65oC
Hillawi Khadrawi
126
4.3.1.2.4 Glucose (%)
Statistically significant results (p ≤ 0.05) were found regarding the effects of hot water
treatments, cultivars and their interaction on glucose in fruit at tamar stage (Figure 4.54).
High temperature treatment for 7 min at 65oC positively decreased the level of glucose as
compared to low temperature treatments. The fruits those were immersed in hot water for
3 min and 5 min at 65oC showed higher glucose of 30.73 and 29.03%, respectively and
these were at par with each other. While, lower amounts of glucose (16.75%) were
recorded in untreated fruits. The Hillawi fruits showed maximum glucose (27.66%) as
compared to the fruits of Khadrawi where glucose contents of 24.12% were noted. The
interaction between hot water treatments and cultivars showed that fruits those were
treated with hot water for 3 and 1 min at 65oC showed higher glucose of 35.84 and
32.06%, respectively in the fruits of Hillawi cultivar and these were at par with each
other. Whereas, lower amounts of glucose (15.99 and 17.50%) were recorded in the fruits
those were untreated in Khadrawi and Hillawi cultivars, respectively and these were at
par with each other. The fruits subjected to hot water immersion for 1 and 5 min at 65oC
tended to have an intermediate effect on glucose of both date palm cultivars.
4.3.1.2.5 Fructose (%)
Effects of hot water treatments, cultivars and interaction between them showed significant
differences (p ≤ 0.05) regarding the fructose in fruit at tamar stage (Figure 4.55). Fruits
immersed in high temperature for 7 min at 65oC lower down the level of fructose contents
than the fruits immersed in low temperature. The fruits those were treated with hot water
for 3 min and 5 min at 65oC showed higher fructose contents of 28.74 and 27.45%,
respectively and these were at par with each other. While, lower amounts of fructose
contents (14.83%) were noted in the fruits those were untreated. Hillawi fruits showed
maximum fructose contents (26.16%) than the fruits of Khadrawi where fructose of
22.15% were recorded. The interaction between hot water treatments and cultivars
showed that higher level of fructose (33.99%) was noted in the fruits those were
immersed in hot water for 3 min at 65oC in Hillawi cultivar. Whereas, lower amounts of
fructose contents of 14.03 and 15.63% were recorded in the fruits those were untreated in
Khadrawi and Hillawi cultivars, respectively and these were at par with each other. The
intermediary effect was recorded in fruits those were immersed in hot water for 1 and 5
min at 65oC regarding the fructose of both date palm cultivars.
127
4.3.1.2.6 Sucrose (%)
The analysed data presented in Figure 4.56 showed significant differences at p ≤ 0.05
regarding the effects of hot water treatments, cultivars and their interaction on sucrose in
fruit at tamar stage. Fruit sucrose level effectively decreased as well as the duration of hot
water immersion increased. Higher sucrose (2.59 and 2.43%) were noted in fruits those
were treated with hot water for 5 min and 3 min, respectively and these were at par with
each other. While, lower sucrose of 1.22% were recorded in the fruits those were
untreated. The Hillawi fruit showed higher sucrose (2.31%) than the fruits of Khadrawi
where sucrose of 1.84% were noted. The interaction between hot water treatments and
cultivars showed that fruits those were immersed in hot water for 3 min, 1 min and 5 min
at 65oC showed higher sucrose (3.16, 2.73 and 2.70%) in the fruits of Hillawi and
Khadrawi cultivars, respectively and these were at par with each other. Whereas, lower
sucrose of 1.11, 1.24 and 1.33% were recorded in fruits those were untreated, immersed
in hot water for 1 min at 65oC and untreated fruits, respectively and these were at par with
each other.
4.3.1.2.7 Reducing sugars (%)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of hot
water treatments, cultivars and their interaction on reducing sugars in fruit at tamar stage
(Figure 4.57). Higher duration heat treatments for 7 min at 65oC positively decreased the
level of reducing sugars than shorter duration heat treatments. The fruits those were
treated with hot water for 3 min and 5 min at 65oC showed higher levels of reducing
sugars (59.47 and 56.48%), respectively and these were at par with each other. While,
lower reducing sugars of 31.58% were noted in the fruits those were untreated. Hillawi
fruits showed higher reducing sugars (53.83%) as compared to the fruits of Khadrawi
where reducing sugars of 46.27% were recorded. The interaction between hot water
treatments and cultivars showed that fruits those were immersed in hot water for 3 min
and 1 min showed higher levels of reducing sugars of 69.83 and 62.79% in the fruit of
Hillawi cultivars, respectively and these were at par with each other. Whereas, fruits those
were untreated showed lower reducing sugars of 30.03 and 33.14% in Khadrawi and
Hillawi cultivar, respectively and these were at par with each other. Hot water immersion
for 1 min at 65oC showed intermediate effect on reducing sugars of both date palm
cultivars.
128
4.3.1.2.8 Total sugars (%)
Total sugars in fruit at tamar stage showed statistically significant differences (p≤0.05)
regarding the effects of hot water treatments, cultivars and interaction between them
(Figure 4.58). Higher duration heat treatments for 7 min at 65oC positively decreased the
level of total sugars than shorter duration heat treatments. Higher amounts of total sugar
contents (61.90 and 59.08%) were recorded in fruits those were treated with hot water for
3 min and 5 min at 65oC, respectively and these were at par with each other. While, lower
total sugars of 32.81% were noted in untreated fruit. The fruit of Hillawi showed
maximum total sugars (56.14%) than the fruit of Khadrawi where total sugars of 48.11%
were recorded. The interaction between hot water treatments and cultivars showed that
fruits those were immersed in hot water for 3 min at 65oC showed higher total sugars of
73.00% in Hillawi cultivar. Whereas, the fruits those were untreated showed lower
amounts of total sugars (31.14 and 34.47%) in Khadrawi and Hillawi cultivar,
respectively and these were at par with each other. The fruits subjected to hot water
immersion for 1 min at 65oC tended to have an intermediate effect on total sugars of both
date palm cultivars.
Figure 4.54 Effects of hot water treatments at 65oC on glucose (%) of Hillawi and
Khadrawi date palm fruit ± S.E.
0
5
10
15
20
25
30
35
40
Glu
cose
(%
)
Duration of HWT at 65oC
Hillawi Khadrawi
129
Figure 4.55 Effects of hot water treatments at 65oC on fructose (%) of Hillawi and
Khadrawi date palm fruit ± S.E.
Figure 4.56 Effects of hot water treatments at 65oC on sucrose (%) of Hillawi and
Khadrawi date palm fruit ± S.E.
0
5
10
15
20
25
30
35
40F
ruct
ose
(%
)
Duration of HWT at 65oC
Hillawi Khadrawi
0
0.5
1
1.5
2
2.5
3
3.5
Su
cro
se (
%)
Duration of HWT at 65oC
Hillawi Khadrawi
130
Figure 4.57 Effects of hot water treatments at 65oC on reducing sugars (%) of
Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.58 Effects of hot water treatments at 65oC on total sugars (%) of Hillawi
and Khadrawi date palm fruit ± S.E.
0
10
20
30
40
50
60
70
80R
edu
cin
g s
ug
ars
(%
)
Duration of HWT at 65oC
Hillawi Khadrawi
0
10
20
30
40
50
60
70
80
To
tal
sug
ars
(%
)
Duration of HWT at 65oC
Hillawi Khadrawi
131
4.3.1.3 Fruit phytonutritional traits
4.3.1.3.1 Total phenolics (mg GAE/100 g)
The analysed data presented in Figure 4.59 showed significant differences (p ≤ 0.05)
regarding the effects of hot water treatments, cultivars and their interaction on total
phenolics in fruit at tamar stage. Higher total phenolics (182.52 and 182.07 mg GAE/100
g) were recorded in the fruits those were treated with hot water for 3 min and 5 min at
65oC, respectively and these were at par with each other. While, lower amounts of total
phenolic contents of 133.73 mg GAE/100 g were noted in the control fruits. Khadrawi
fruits showed higher total phenolics (172.51 mg GAE/100 g) as compared to the fruits of
Hillawi where total phenolics of 156.17 mg GAE/100 g were noted. The interaction
between hot water treatments and cultivars showed that fruits those were immersed in hot
water for 5 min, 3 min and 7 min at 65oC showed higher total phenolics in Khadrawi,
Hillawi and Khadrawi cultivars, respectively and these were at par with each other.
Whereas, lower total phenolics of 128.03, 139.43, 142.81 and 152.10 mg GAE/100 g
were noted in the fruits those were untreated and immersed in hot water for 7 min and 1
min at 65oC in Hillawi, Khadrawi, Hillawi and Khadrawi cultivars, respectively and these
were at par with each other.
4.3.1.3.2 Total flavonoids (mg CEQ/100 g)
Total flavonoids in fruit at tamar stage showed significant differences (p ≤ 0.05)
regarding the effects of hot water treatments and interaction while cultivars did not differ
significantly (Figure 4.60). The fruits those were immersed in hot water for 3 min, 5 min
and 1 min at 65oC showed higher amounts of total flavonoids (27.80, 26.81 and 24.92 mg
CEQ/100 g), respectively and these were at par with each other. While, lower total
flavonoids of 19.33 mg CEQ/100 g were noted in the control fruits. The interaction
between hot water treatments and cultivars showed that fruits those were treated with hot
water for 3 min, 5 min and 1 min at 65oC showed higher total flavonoids (32.20, 28.52
and 28.17 mg CEQ/100 g) in Hillawi, Khadrawi and Hillawi cultivars, respectively and
these were at par with each other. Whereas, lower total flavonoids (18.48, 20.18, 21.67
and 22.06 mg CEQ/100 g) were recorded in fruits those were untreated and immersed in
hot water for 1 min and 7 min at 65oC in Khadrawi, Hillawi, Khadrawi and Hillawi
cultivars, respectively and these were at par with each other.
4.3.1.3.3 Total tannins (%)
Statistically significant results (p ≤ 0.05) were found regarding the effects of hot water
treatments, cultivars and interaction between them on total tannins in the fruit at tamar
132
stage (Figure 4.61). Hot water treatment with an exposure time of 5 min at 65oC showed
lower total tannins of 0.219% and higher total tannins of 0.414% were noted in fruits
those were untreated. The Hillawi fruits showed lower amounts of total tannin contents
(0.267%) than the fruit of Khadrawi where total tannins of 0.325% were recorded. The
interaction between hot water treatments and cultivars showed that fruits those were
treated with hot water for 3 min and 1 min at 65oC showed lower total tannins of 0.161
and 0.192% in Hillawi cultivar, respectively and these were at par with each other. While,
fruits those were untreated showed higher total tannins of 0.435% in Khadrawi cultivar.
4.3.1.3.4 Total antioxidants (%)
The effects of hot water treatments, cultivars and interaction between them were found
significant at p ≤ 0.05 for total antioxidants in the fruit at tamar stage (Figure 4.62).
Higher antioxidants activities of 61.14 and 55.68% were recorded in the fruits those were
treated with hot water with an exposure time of 5 min and 3 min at 65oC, respectively and
these were at par with each other. While, lower total antioxidants of 28.76% were noted
in the control fruit. Khadrawi fruit showed higher total antioxidants activities (50.34%) as
compared to the fruits of Hillawi where total antioxidants activities of 45.33% were
noted. The interaction between hot water treatments and cultivars showed that fruits those
were immersed in hot water for 5 min at 65oC showed higher total antioxidants activities
of 72.84% in Khadrawi cultivar. Whereas, minimum total antioxidants activities of 26.46
and 31.07% were noted in the control fruit of Hillawi and Khadrawi cultivars,
respectively and these were at par with each other.
133
Figure 4.59 Effects of hot water treatments with different timings by keeping
temperature constant at 65oC on total phenolics (mg GAE/100 g) of
Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.60 Effects of hot water treatments with different timings by keeping
temperature constant at 65oC on total flavonoids (mg CEQ/100 g) of
Hillawi and Khadrawi date palm fruit ± S.E.
0
50
100
150
200
250T
PC
(m
g G
AE
/10
0 g
)
Duration of HWT at 65oC
Hillawi Khadrawi
0
5
10
15
20
25
30
35
40
TF
C (
mg
CE
Q/1
00
g)
Duration of HWT at 65oC
Hillawi Khadrawi
134
Figure 4.61 Effects of hot water treatments with different timings by keeping
temperature constant at 65oC on total tannins (%) of Hillawi and
Khadrawi date palm fruit ± S.E.
Figure 4.62 Effects of hot water treatments with different timings by keeping
temperature constant at 65oC on total antioxidants (%) of Hillawi
and Khadrawi date palm fruit ± S.E.
00.05
0.10.15
0.20.25
0.30.35
0.40.45
0.5T
ota
l ta
nn
ins
(%)
Duration of HWT at 65oC
Hillawi Khadrawi
0
10
20
30
40
50
60
70
80
Tota
l an
tiox
idan
ts (
%)
Duration of HWT at 65oC
Hillawi Khadrawi
135
4.3.1.4 Fruit organoleptic traits
4.3.1.4.1 Colour score
The analysed data presented in Figure 4.63 showed significant differences (p ≤ 0.05)
regarding the effects of hot water treatments and interaction while non-significant results
were found in cultivars on colour score. Higher colour score index of 4.33 marked by the
panellist was recorded in fruits those were treated with hot water for an exposure time of
5 min at 65oC. While, minimum colour score indexes of 1.16 and 1.50 ranked by the
panellists in the fruits those were untreated and immersed in hot water for 1 min at 65oC,
respectively and these were at par with each other. The interaction between hot water
treatments and cultivars showed that fruits those were treated with hot water for an
exposure times of 5 min, 2 min and 1 min at 65oC showed higher colour score indexes of
5.00, 4.66 and 4.00 rated by the panellists in Khadrawi, Hillawi and Khadrawi fruits ,
respectively and these were at par with each other. Whereas, minimum colour scores
(1.00, 1.33, 1.33, 1.33 and 1.66) were marked by the panellists in the fruits those were
untreated, immersed in hot water for 7 min, 1 min at 65oC, control and immersed in hot
water for 1 min at 65oC in Khadrawi, Hillawi, Khadrawi and Hillawi fruits, respectively
and these were at par with each other.
4.3.1.4.2 Taste score
Statistically significant differences were found at p ≤ 0.05 regarding the effects of hot
water treatments and interaction while cultivars showed non-significant results for taste
scores (Figure 4.64). The fruits those were treated with hot water for an exposure times of
5 min and 3 min at 65oC showed higher taste scores of 4.00 and 3.66 ranked by the
panellists, respectively and these were at par with each other. While, fruits those were
untreated showed lower taste score of 0.50 marked by the panellists. The interaction
between hot water treatments and cultivars showed that fruits those were immersed in hot
water for 5 min, 3 min and 1 min showed higher indexes of taste scores (5.00, 4.66 and
4.00) rated by the panellist, respectively and these were at par with each other. Whereas,
lower indexes of taste scores (0.33, 0.66, 1.33 and 1.33) were marked by the panellists in
the control fruits, immersed in hot water for 7 min and 1 min at 65oC in Hillawi,
Khadrawi, Hillawi and Khadrawi fruits, respectively and these were at par with each
other.
4.3.1.4.3 Texture score
The effects of hot water treatments and interaction were found significant (p ≤ 0.05) while
cultivars showed non-significant results for texture score (Figure 4.65). Maximum texture
136
score indexes of 4.16 and 3.83 were marked by the panellists in the fruits those were
treated with hot water for an exposure times of 5 min and 3 min at 65oC, respectively and
these were at par with each other. While minimum texture score index of 0.83 rated by
the panellist in the control fruits. The interaction between hot water treatments and
cultivars showed that fruits those were untreated, immersed in hot water for 5 min, 3 min
and 1 min at 65oC showed higher colour scores (5.00, 4.66 and 4.00) were marked by the
panellist in Khadrawi, Hillawi and Khadrawi cultivars, respectively and these were at par
with each other. Whereas, minimum texture score indexes of 0.66, 1.00, 1.33 and 1.66
ranked by the panellist in the fruits those were untreated and immersed in hot water for 1
min and 7 min at 65oC in Hillawi, Khadrawi and Hillawi cultivars, respectively and these
were at par with each other.
4.3.1.4.4 Firmness score
The analysed data presented in Figure 4.66 showed significant differences regarding the
effects of hot water treatments and interaction while non-significant difference was found
in cultivars. The fruits those were treated with hot water for an exposure times of 5 min
and 3 min at 65oC showed maximum firmness scores (4.16 and 3.66) marked by the
panellists, respectively and these were at par with each other. The interaction between hot
water treatments and cultivars showed that fruits those were immersed in hot water for 3
min and 5 min at 65oC attained higher firmness scores of 4.66 and 4.66 rated by the
panellist in Hillawi and Khadrawi, respectively and these were at par with each other.
While, minimum firmness score indexes of 0.66, 1.00, 1.33 and 1.33 were marked by the
panellist in the fruits those were untreated, immersed in hot water for 7 min and 1 min at
65oC in Hillawi, Khadrawi, Hillawi and Khadrawi cultivars, respectively and these were
at par with each other.
4.3.1.4.5 Astringency score
Statistically significant results (p ≤ 0.05) were found regarding the effects of hot water
treatments and interaction while cultivars showed non-significant results for astringency
score (Figure 4.67). Maximum astringency scores of 4.16 and 4.16 marked by the
panellist in the fruits those were treated with hot water for 5 min and 3 min at 65oC,
respectively and these were at par with each other. While, minimum astringency score of
1.33 rated by the panellist in the control fruits. The interaction between hot water
treatments and cultivars showed that higher astringency scores (5.00, 4.66, 4.00, 4.00 and
3.66) ranked by the panellist in the fruits those were immersed in hot water for 3 min, 5
min, 7 min, 1min and 5 min in Hillawi, Khadrawi, Khadrawi, Hillawi and Hillawi
137
cultivars, respectively and these were at par with each other. Whereas, minimum
astringency scores of 1.33, 1.33, 1.66 and 2.00 marked by the panellist in the fruits those
were untreated, immersed in hot water for 1 min and 7 min at 65oC in Khadrawi, Hillawi,
Khadrawi and Hillawi, respectively and these were at par with each other.
4.3.1.4.6 Overall acceptability score
The effects of hot water treatments and interaction showed significant differences (p ≤
0.05) while non-significant results were found in cultivars for overall acceptability score
(Figure 4.68). The fruits those were treated with hot water for 5 min and 3 min at 65oC
showed higher overall acceptability scores of 3.83 and 3.50 marked by the panellists,
respectively and these were at par with each other. While, minimum overall acceptability
score of 0.50 ranked by the panellist in the control fruits. The interaction between hot
water treatments and cultivars showed that fruits those were immersed in hot water for 3
min, 5 min and 7 min showed maximum overall acceptability scores of 4.66, 4.33 and
3.66 rated by the panellists in Hillawi and Khadrawi, respectively and these were at par
with each other. Whereas, minimum overall acceptability scores (0.33, 0.66, 1.33 and
1.33) marked by the panellists in the control fruits and immersed in hot water for 1 min at
65oC in Khadrawi, Hillawi, Khadrawi and Hillawi cultivars, respectively and these were
at par with each other.
In general, panellists preferred Hillawi fruits those were immersed in hot water for 3 min
at 65oC and Khadrawi fruits treated with hot water for 5 min at 65
oC over all other
treatments.
138
Figure 4.63 Effects of hot water treatments at 65oC on colour score of Hillawi
and Khadrawi date palm fruit ± S.E.
Figure 4.64 Effects of hot water treatments at 65oC on taste score of Hillawi and
Khadrawi date palm fruit ± S.E.
0
1
2
3
4
5
6C
olo
ur
sco
re
Duration of HWT at 65oC
Hillawi Khadrawi
0
1
2
3
4
5
6
Ta
ste
sco
re
Duration of HWT at 65oC
Hillawi Khadrawi
139
Figure 4.65 Effects of hot water treatments at 65oC on texture score of Hillawi
and Khadrawi date palm fruit ± S.E.
Figure 4.66 Effects of hot water treatments at 65oC on firmness score of Hillawi
and Khadrawi date palm fruit ± S.E.
0
1
2
3
4
5
6T
extu
re s
core
Duration of HWT at 65oC
Hillawi Khadrawi
0
1
2
3
4
5
6
Fir
mn
ess
sco
re
Duration of HWT at 65oC
Hillawi Khadrawi
140
Figure 4.67 Effects of hot water treatments at 65oC on astringency score of
Hillawi and Khadrawi date palm fruit ± S.E.
Figure 4.68 Effects of hot water treatments at 65oC on overall acceptability
score of Hillawi and Khadrawi date palm fruit ± S.E.
0
1
2
3
4
5
6A
strin
gen
cy s
core
Duration of HWT at 65oC
Hillawi Khadrawi
-1
0
1
2
3
4
5
6
Ov
era
ll a
ccep
tab
ilit
y s
core
Duration of HWT at 65oC
Hillawi Khadrawi
141
4.3.2 Study-3 Effects of different chemicals on the ripening
behaviour and fruit quality of date palm.
4.3.2.1 Results
4.3.2.1.1 Fruit physical traits
4.3.2.1.1.1 Uniform fruit ripening index (%)
The analysed data presented in Figure 4.69 showed significant differences (p ≤ 0.05)
regarding the effects of chemical treatments while cultivars and their interaction were
found non-significant regarding uniform fruit ripening index in fruits at tamar stage.
Fruits those were treated with different chemicals progressively increased the index of
uniform fruit ripening as compared to fruits without chemicals in both date palm
cultivars. The fruits those were treated with 3% acetic acid (T3) showed higher uniform
fruit ripening index of 64.24% followed by fruits those were treated with 2% acetic acid
(T2) where uniform fruit ripening index of 55.95% was recorded than all other
treatments. Whereas, minimum uniform fruits ripening index of 14.99% was noted in the
fruits those were untreated (T1). The fruits those were treated with T4 (dipping in 2%
NaCl), T5 (dipping in 3% NaCl), T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L
ethephon) and T9 (dipping in 3% acetic acid+3% NaCl+4 ml/L ethephon) tended to have
an intermediate effect on uniform fruit ripening index of both date palm cultivars.
4.3.2.1.1.2 Fruit weight loss (%)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of
chemical treatments and cultivars while interaction between them showed non-significant
results for fruit weight loss in fruits at tamar stage (Figure 4.70). Fruits dipped in various
types of chemicals showed progressive decrease in weight loss as compared to untreated
fruits. Minimum weight loss of 15.06% was recorded in the fruits those were treated with
3% acetic acid (T3) followed by 2% acetic acid (T2) where weight loss of 17.70% was
noted in the fruits. Whereas, maximum losses in weights of 29.20, 28.73 and 28.65%
were noted in the fruits those were untreated, dipped in 2 ml/L ethephon (T6) and 4 ml/L
(T7) ethephon, respectively and these were at par with each other. The Hillawi fruits
showed higher loss in weight (24.56%) as compared to the fruits of Khadrawi where loss
in weight of 23.51% was recorded. The intermediary effect was noted in fruits those were
treated with T4 (dipping in 2% NaCl), T5 (dipping in 3% NaCl), T8 (dipping in 2% acetic
142
acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3% acetic acid+3% NaCl+4 ml/L
ethephon) regarding the fruit weight loss of both date palm cultivars.
4.3.2.1.1.3 Fruit moisture content (%)
The effects of chemical treatments and cultivars were found significant (p ≤ 0.05) while
interaction between them showed non-significant results for moisture contents in fruits at
tamar stage (Figure 4.71). Fruit moisture contents decreased progressively as well as fruit
goes to ripening. The fruits those were treated with 2% acetic acid (T2) and 3 % acetic
acid (T3) showed higher moisture contents of 24.71 and 24.23, respectively and these
were at par with each other than all other treatments. Whereas, minimum moisture
contents of 15.73% were noted in the fruits those were without chemical treatments (T1).
The fruits of Khadrawi showed higher level of moisture contents (20.86%) as compared
to the fruits of Hillawi where moisture contents of 20.02% were noted. The fruits those
were treated with T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon) and T9
(dipping in 3% acetic acid+3% NaCl+4 ml/L ethephon) tended to have an intermediate
effect on fruit moisture contents of both date palm cultivars.
4.3.2.1.1.4 Fruit flesh weight (g)
Statistically significant differences (p ≤ 0.05) were found regarding the effects of
chemical treatments and cultivars while interaction between them showed non-significant
results for flesh weight in fruits at tamar stage (Figure 4.72). Higher flesh weights of 4.34
and 4.00 g were noted in the fruits those were treated with 3 % acetic acid and 2% acetic
acid, respectively and these were at par with each other than all other chemicals
treatments. While, lower flesh weights of 3.22, 3.23, 32.28, 3.40, 3.40 and 3.57 g were
recorded in the fruits those were untreated, 2 ml/L ethephon, 3% acetic acid+3% NaCl+4
ml/L ethephon (T9), 2% acetic acid, 2% NaCl, 2 ml/L ethephon, 4 ml/L ethephon (T8)
and 2% NaCl, respectively and these were at par with each other. The Khadrawi fruits
showed higher flesh weight (3.68 g) than the fruits of Hillawi where flesh weight of 3.68
g was measured.
4.3.2.1.1.5 Fruit pit weight (g)
The analysed data presented in Figure 4.73 showed statistically non-significant
differences (p ≥ 0.05) regarding the effects of chemical treatments and interaction while a
significant difference was found in cultivars for pit weight in fruits at tamar stage. The
Hillawi fruits shoed higher pit weight (0.64 g) as compared to the fruits of Khadrawi
where pit weight of 0.59 g was measured.
143
Figure 4.69 Effects of different chemicals on uniform fruit ripening index (%) of
Hillawi and Khadrawi date palm fruit after incubation at 40±1oC for 72 h
± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic acid+2%
NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3% NaCl+4 ml/L
ethephon)
Figure 4.70 Effects of different chemicals on uniform fruit weight loss (%) of Hillawi
and Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
0
10
20
30
40
50
60
70
80
T1 T2 T3 T4 T5 T6 T7 T8 T9
Un
iform
fru
it r
ipen
ing
in
dex
(%
)
Hillawi Khadrawi
0
5
10
15
20
25
30
35
T1 T2 T3 T4 T5 T6 T7 T8 T9
Fru
it w
eig
ht
loss
(%
)
Hillawi Khadrawi
144
Figure 4.71 Effects of different chemicals on fruit moisture content (%) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
Figure 4.72 Effects of different chemicals on fruit flesh weight (g) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
0
5
10
15
20
25
30
T1 T2 T3 T4 T5 T6 T7 T8 T9
Mo
istu
re c
on
ten
t (%
)
Hillawi Khadrawi
0
1
2
3
4
5
T1 T2 T3 T4 T5 T6 T7 T8 T9
Fru
it f
lesh
wei
gh
t (g
)
Hillawi Khadrawi
145
Figure 4.73 Effects of different chemicals on fruit pit weight (g) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
4.3.2.2.1 Fruit biochemical traits
4.3.2.2.1.1 Total soluble solids concentration (oBrix)
Statistically significant differences (p ≤ 0.05) were found regarding the effects of
chemical treatments and cultivars while their interaction showed non-significant results
for total soluble solids concentration in fruit at tamar stage (Figure 4.74). Total soluble
solid concentration increased with the progression of fruit ripening at tamar stage. The
fruits those were treated with 3% acetic acid (T3) showed higher amounts of total soluble
solids concentration (10.71 oBrix) as compared to the fruit of all other treatments.
Whereas, lower total soluble solids concentration of 6.58 oBrix were noted in the fruits
those were untreated (T1). The Hillawi fruits showed higher total soluble solids
concentration (8.56 oBrix) than the fruits of Khadrawi where total soluble solids contents
of 7.95 oBrix were recorded. The fruits those were treated with T4 (dipping in 2% NaCl)
and T5 (dipping in 3% NaCl) tended to have an intermediate effect on total soluble solid
concentration of both date palm cultivars.
4.3.2.2.1.2 Total titratable acidity (%)
The effects of chemical treatments and cultivars were found significant while interaction
between them showed non-significant results for total titratable acidity in fruits at tamar
stage (Figure 4.75). The fruits those were treated with 3% acetic acid showed lower level
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
T1 T2 T3 T4 T5 T6 T7 T8 T9
Fru
it p
it w
eig
ht
(g)
Hillawi Khadrawi
146
of total titratable acidity (0.118%) followed by 2% acetic acid (T3) where titratable
acidity of 0.135% was recorded than all other chemical treatments. While, higher value of
total titratable acidity (0.207%) was noted in the fruits those were untreated (T1). The
fruits of Hillawi showed lower level of total titratable acidity (0.161%) than the Khadrawi
fruits where total titratable acidity of 0.169% was recorded. The fruits those were treated
with T4 (dipping in 2% NaCl) and T5 (dipping in 3% NaCl) tended to have an
intermediate effect on total titratable acidity of both date palm cultivars.
4.3.2.2.1.3 Ascorbic acid (mg 100 g-1
)
Ascorbic acid in fruit at tamar stage showed significant differences at p ≤ 0.05 regarding
the effects of chemicals treatments and cultivars while non-significant results were found
in their interaction (Figure 4.76). Maximum amounts of ascorbic acid (0.916 and 0.883
mg 100 g-1
) were noted in the fruits those were treated with 3% acetic acid (T3) and 2%
acetic acid (T2) and those were at par with each other than all other chemical treatments.
While, lower ascorbic acid of 0.733 mg 100 g-1
were noted in the control fruit (T1) and
these were at par with the fruit of T7 (4 ml/L ethephon, T9 (3% acetic acid+3% NaCl+4
ml/L ethephon and T6 (2 ml/L ethephon) where ascorbic acid were 0.766, 0.777 and
0.790 mg 100 g-1
, respectively and these were at par with each other. The Hillawi fruit
showed higher level of ascorbic acid (0.834 mg 100 g-1
) as compared to the fruit of
Khadrawi where ascorbic acid of 0.793 mg 100 g-1
was recorded. The fruits those were
treated with T4 (dipping in 2% NaCl) and T5 (dipping in 3% NaCl) tended to have an
intermediate effect on ascorbic acid of both date palm cultivars.
147
Figure 4.74 Effects of different chemicals on total soluble solids (oBrix) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
Figure 4.75 Effects of different chemicals on total titratable acidity (%) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
0
2
4
6
8
10
12
T1 T2 T3 T4 T5 T6 T7 T8 T9
TS
S (
oB
rix)
Hillawi Khadrawi
0
0.05
0.1
0.15
0.2
0.25
T1 T2 T3 T4 T5 T6 T7 T8 T9
Aci
dit
y (
%)
Hillawi Khadrawi
148
Figure 4.76 Effects of different chemicals on ascorbic acid (mg 100 g-1
) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
4.3.2.2.1.4 Glucose (%)
The analysed data presented in Figure 4.77 showed significant differences (p ≤ 0.05)
regarding the effects of chemical treatments and cultivars while interaction between them
was found non-significant for glucose in fruit at tamar stage. Higher glucose contents of
29.06% were recorded in the fruits those were treated with 3% acetic acid (T3) followed
by 2% acetic acid (T2) where glucose were 27.03% than all other treatments. Whereas,
lower amounts of glucose contents (19.60 and 20.55%) were noted in the fruits those
were untreated and dipped in 4 ml/L ethephon solutions (T7), respectively and these were
at par with each other. The Hillawi fruits showed higher glucose (24.16%) than the fruits
of Khadrawi where glucose of 22.70% were recorded. The intermediary effect was noted
in fruits those were treated with T4 (dipping in 2% NaCl), T5 (dipping in 3% NaCl), T8
(dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3% acetic
acid+3% NaCl+4 ml/L ethephon) regarding the glucose of both date palm cultivars.
4.3.2.2.1.5 Fructose (%)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of
chemical treatments and cultivars while interaction between them showed non-significant
results for fructose in fruit at tamar stage (Figure 4.78). The fruits those were treated with
0
0.2
0.4
0.6
0.8
1
1.2
T1 T2 T3 T4 T5 T6 T7 T8 T9
Asc
orb
ic a
cid
(m
g 1
00
g-1
)
Hillawi Khadrawi
149
3% acetic acid (T3) showed higher amounts of fructose (27.11%) followed by 2% acetic
acid (T2) where fructose of 25.56% was noted than all other chemical treatments. While,
lower fructose of 17.71% were recorded in the fruits those were untreated (T1). The fruits
of Hillawi showed higher fructose (22.51%) as compared to the fruits of Khadrawi where
fructose of 21.53% was recorded. The fruits those were treated with T8 (dipping in 2%
acetic acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3% acetic acid+3% NaCl+4
ml/L ethephon) tended to have an intermediate effect on fruit fructose of both date palm
cultivars.
4.3.2.2.1.6 Sucrose (%)
The effects of chemical treatments and cultivars were found significant while interaction
between them showed non-significant results for sucrose in fruit at tamar stage (Figure
4.79). Higher sucrose contents of 3.19% were noted in the fruits those were treated with
3% acetic acid (T3) followed by 2% acetic acid (T2) where sucrose were 2.89% than all
other chemical treatments. Whereas, lower values of sucrose (1.92, 2.09 and 2.15%) were
noted in the fruits of T1 (control), T9 (3% acetic acid+3% NaCl+4 ml/L ethephon) and T8
(2% acetic acid+2% NaCl+2 ml/L ethephon), respectively and these were at par with each
other. The Hillawi fruit showed higher sucrose (2.56%) as compared to the fruit of
Khadrawi where sucrose contents of 2.30% were noted. The intermediary effect was
noted in fruits those were treated with T4 (dipping in 2% NaCl), T5 (dipping in 3%
NaCl), T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3%
acetic acid+3% NaCl+4 ml/L ethephon) regarding the sucrose of both date palm cultivars.
4.3.2.2.1.7 Reducing sugars (%)
Reducing sugars in fruit at tamar stage showed statistically significant differences (p ≤
0.05) regarding the effects of chemicals treatments and cultivars while their interaction
was found non-significant (Figure 4.80). The fruits those were treated with 3% acetic acid
(T3) showed higher amounts of reducing sugars (56.18%) followed by 2% acetic acid
(T2) where reducing sugars were 52.59% than all other chemical treatments. Meanwhile,
minimum reducing sugar contents of 37.32% were noted in the fruits those were untreated
(T1). The Hillawi fruits showed higher reducing sugars (46.67%) as compared to the fruits
of Khadrawi where reducing sugars of 44.23% were noted. The fruits those were treated
with T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3%
acetic acid+3% NaCl+4 ml/L ethephon) tended to have an intermediate effect on fruit
reducing sugars of both date palm cultivars.
150
4.3.2.2.1.8 Total sugars (%)
The analysed data presented in Figure 4.81 showed significant differences (p ≤ 0.05)
regarding the effects of chemical treatments and cultivars while interaction between them
was found non-significant for total sugars in fruit at tamar stage (Figure 4.3.2.2.1.8).
Maximum total sugar contents of 59.38% were recorded in the fruits those were treated
with 3% acetic acid (T3) followed by 2% acetic acid (T2) where total sugars were 55.48%
than all other chemical treatments. Whereas, minimum amounts of total sugars (39.25%)
were noted in the control fruits (T1). The fruit of Hillawi showed higher total sugars
(49.24%) as compared to the fruits of Khadrawi where total sugars of 46.54% were
recorded. The intermediary effect was noted in fruits those were treated with T4 (dipping
in 2% NaCl), T5 (dipping in 3% NaCl), T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L
ethephon) and T9 (dipping in 3% acetic acid+3% NaCl+4 ml/L ethephon) regarding the
total sugars of both date palm cultivars.
Figure 4.77 Effects of different chemicals on glucose (%) of Hillawi and Khadrawi date
palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
0
5
10
15
20
25
30
35
T1 T2 T3 T4 T5 T6 T7 T8 T9
Glu
cose
(%
)
Hillawi Khadrawi
151
Figure 4.78 Effects of different chemicals on fructose (%) of Hillawi and Khadrawi date
palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+ 3%
NaCl+4 ml/L ethephon)
Figure 4.79 Effects of different chemicals on sucrose (%) of Hillawi and Khadrawi date
palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
0
5
10
15
20
25
30
35
T1 T2 T3 T4 T5 T6 T7 T8 T9
Fru
cto
se (
%)
Hillawi Khadrawi
0
0.5
1
1.5
2
2.5
3
3.5
4
T1 T2 T3 T4 T5 T6 T7 T8 T9
Su
cro
se (
%)
Hillawi Khadrawi
152
Figure 4.80 Effects of different chemicals on reducing sugars (%) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+ 3%
NaCl+4 ml/L ethephon)
Figure 4.81 Effects of different chemicals on total sugars (%) of Hillawi and Khadrawi
date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
0
10
20
30
40
50
60
70
T1 T2 T3 T4 T5 T6 T7 T8 T9
Red
uci
ng
su
ga
rs (
%)
Hillawi Khadrawi
0
10
20
30
40
50
60
70
T1 T2 T3 T4 T5 T6 T7 T8 T9
To
tal
sug
ars
(%
)
Hillawi Khadrawi
153
4.3.2.3.1 Fruit phytonutritional traits
4.3.2.3.1.1 Total phenolics (mg GAE/100 g)
Total phenolics in fruit at tamar stage showed significant differences (p ≤ 0.05) regarding
the effects of chemical treatments and cultivars while interaction between them was found
non-significant (Figure 4.82). Higher amounts of total phenolics (248.83, 245.18 and
234.28 mg GAE/100) were recorded in fruit of T3 (3% acetic acid), T2 (2% acetic acid)
and T4 (2% NaCl), respectively and these were at par with each other. While, lower total
phenolics of 208.50, 215.39 and 216.22 mg GAE/100 g were noted in the fruit of T1
(control), T6 (2 ml/L ethephon) and T7 (4 ml/L ethephon), respectively and these were at
par with each other. The fruit of Khadrawi showed higher total phenolic contents (233.48
mg GAE/100 g) than the fruit of Khadrawi where total phenolics of 222.80 mg GAE/100
g were recorded.
4.3.2.3.1.2 Total flavonoids (mg CEQ/100 g)
The analysed data presented in Figure 4.83 showed significant differences (p ≤ 0.05)
regarding the effects of chemical treatments and cultivars while interaction between them
was found non-significant for total flavonoids in fruit at tamar stage. The fruits those
were treated with 3% acetic acid (T3) and 2% acetic acid (T2) showed higher values of
total flavonoids (27.27 and 26.82 mg CEQ/100 g), respectively and these were at par with
each other. While, lower total flavonoids of 21.73, 21.80, 21.81, 22.82, 22.84 and 23.29
mg CEQ/100 g were noted in the fruit of T1 (control), T9 (3% acetic acid+3% NaCl+4
ml/L ethephon), T8 (2% acetic acid+2% NaCl+2 ml/L ethephon), T6 (2 ml/L ethephon),
T5 (3% NaCl) and T7 (4 ml/L ethephon), respectively and these were at par with each
other. The Hillawi fruit showed higher total flavonoids (24.42 mg CEQ/100 g) as
compared to the fruit of Khadrawi where total flavonoids of 22.71 mg CEQ/100 g were
recorded.
4.3.2.3.1.3 Total tannins (%)
Statistically significant results were found at p ≤ 0.05 regarding the effects of chemicals
treatments and cultivars while their interaction showed non-significant differences for
total tannins in fruit at tamar stage (Figure 4.84). Lower amounts of total tannins (0.196,
0.200 and 0.215% were recorded in the fruit of T3 (3% acetic acid), T4 (2% NaCl) and
T2 (2% acetic acid), respectively and these were at par with each other. Whereas, higher
total tannins of 0.339 and 0.328% were recorded in the fruits of T1 (control) and T9 (3%
acetic acid+3% NaCl+4 ml/L ethephon), respectively and these were at par with each
154
other. The fruit of Hillawi showed lower total tannins (0.252%) than the fruit of Khadrawi
where total tannins of 0.281% were noted.
4.3.2.3.1.4 Total antioxidants (%)
Total antioxidants in the fruit at tamar stage showed significant differences (p ≤ 0.05)
regarding the effects of chemical treatments and cultivars while interaction between them
was found non-significant (Figure 4.85). Higher antioxidants of 61.39 and 56.49% were
noted in the fruits of T3 (3% acetic acid) and T2 (2% acetic acid), respectively and these
were at par with each other. While, lower antioxidants activities (48.02, 51.27, 51.28,
52.68, 52.80 and 52.95%) were noted in the fruits of T1 (control), T6 (2 ml/L ethephon),
T9 (3% acetic acid+3% NaCl+4 ml/L ethephon), T8 (2% acetic acid+2% NaCl+2 ml/L
ethephon), T4 (2% NaCl) and T5 (3% NaCl), respectively and these were at par with each
other. The Khadrawi fruits showed higher antioxidants activities (54.71%) as compared to
the fruits of Hillawi where total antioxidants activities of 52.25% were recorded.
Figure 4.82 Effects of different chemicals on total phenolics (mg GAE/100 g) of Hillawi
and Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
0
50
100
150
200
250
300
T1 T2 T3 T4 T5 T6 T7 T8 T9
TP
C (
mg
GA
E/1
00
g)
Hillawi Khadrawi
155
Figure 4.83 Effects of different chemicals on total flavonoids (mg CEQ/100 g) of Hillawi
and Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
Figure 4.84 Effects of different chemicals on total tannins (%) of Hillawi and Khadrawi
date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6= dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic
acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%
NaCl+4 ml/L ethephon)
0
5
10
15
20
25
30
35
T1 T2 T3 T4 T5 T6 T7 T8 T9
TF
C (
mg
CE
Q/1
00
g)
Hillawi Khadrawi
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
T1 T2 T3 T4 T5 T6 T7 T8 T9
To
tal
tan
nin
s (%
)
Hillawi Khadrawi
156
Figure 4.85 Effects of different chemicals on total antioxidants (%) of Hillawi and
Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in % acetic acid+2%
NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3% NaCl+4 ml/L
ethephon)
4.3.2.4.1 Fruit organoleptic traits
4.3.2.4.1.1 Colour score
The analysed data presented in Figure 4.86 showed significant results (p ≤ 0.05)
regarding the effects of chemical treatments while cultivars and interaction showed non-
significant differences for colour score. Maximum colour score index of 4.33 was marked
by the panellist in the fruits those were treated with 3% acetic acid (T3) followed by 2%
acetic acid (T2) where colour score index was 3.50 ranked by the panellists than all other
chemical treatments. While, minimum colour score indexes of 1.83, 1.83, 2.16, 2.33 and
2.33 were marked by the panellists in the fruits of T1 (control), T9 (dipping in 3% acetic
acid+ 3% NaCl+4 ml/L ethephon), T7 (4 ml/L ethephon), T8 (dipping in 2% acetic acid+
2% NaCl+2 ml/L ethephon) and T6 (2 ml/L ethephon), respectively and these were at par
with each other. The intermediary effect was noted in fruits those were treated with T4
(dipping in 2% NaCl) and T5 (dipping in 3% NaCl) regarding the colour score of both
date palm cultivars.
4.3.2.4.1.2 Taste score
Statistically significant differences were found at p ≤ 0.05 regarding the effects of
chemical treatments while cultivars and interaction showed non-significant differences
0
10
20
30
40
50
60
70
T1 T2 T3 T4 T5 T6 T7 T8 T9
Tota
l an
tiox
idan
ts (
%)
Hillawi Khadrawi
157
for taste score (Figure 4.87). The fruits those were treated with 3% acetic acid (T3)
showed higher index of taste score (4.33) marked by the panellists followed by 2% acetic
acid (T2) where taste score was 3.50 ranked by the panellists. While, minimum taste
scores indexes of 1.83, 1.83, 2.16, 2.33 and 2.33 were rated by the panellists in the fruits
of T1 (control), T9 (dipping in 3% acetic acid+ 3% NaCl+4 ml/L ethephon), T7 (4 ml/L
ethephon), T8 (dipping in 2% acetic acid+ 2% NaCl+2 ml/L ethephon) and T6 (2 ml/L
ethephon), respectively and these were at par with each other.
4.3.2.4.1.3 Texture score
Effects of chemicals treatments showed significant differences (p ≤ 0.05) while non-
significant results were found in cultivars and interaction on texture scores in the fruits at
tamar stage (Figure 4.88). Maximum values of texture scores (4.66 and 3.83) were ranked
by the panellist in fruits of T3 (3% acetic acid) and T2 (2% acetic acid), respectively and
these were at par with each other. Whereas, minimum texture scores indexes of 1.50,
2.16, 2.16 and 2.33 were marked by the panellists in the fruits of T1 (control), T9
(dipping in 3% acetic acid+ 3% NaCl+4 ml/L ethephon), T7 (4 ml/L ethephon) and T6 (2
ml/L ethephon), respectively and these were at par with each other.
4.3.2.4.1.4 Firmness score
Firmness scores in the fruits at tamar stage showed significant (p ≤ 0.05) results regarding
the effects of chemical treatments while non-significant differences were found in
cultivars and interaction (Figure 4.89). Higher firmness score index of 4.83 marked by the
panellists was noted in the fruits those were treated with 3% acetic acid (T3) followed by
the fruits of T2 and T4 where firmness indexes were 4.00 and 3.50, respectively and these
were at par with each other. While, minimum firmness scores (1.16 and 1.50) were rated
by the panellist in the fruits of T1 (control) and T9 (dipping in 3% acetic acid+ 3%
NaCl+4 ml/L ethephon), respectively and these were at par with each other. The
intermediary effect was noted in fruits those were treated with T4 (dipping in 2% NaCl)
and T5 (dipping in 3% NaCl) regarding the firmness score of both date palm cultivars.
4.3.2.4.1.5 Astringency score
Statistically significant results were found regarding the effects of chemical treatments
while cultivars and interaction showed non-significant differences for astringency scores
in fruits at tamar stage (Figure 4.90). Maximum astringency score index of 4.83 marked
by the panellists was received in the fruits those were treated with 3% acetic acid (T3)
followed by fruits those were dipped in 2% acetic acid (T2) where astringency score was
3.83 rated by the panellists than the fruits of all other treatments. Whereas, minimum
158
astringency score indexes (1.16, 1.33 and 1.83) were marked by the panellists in the fruits
of T1 (control), T9 (dipping in 3% acetic acid+ 3% NaCl+4 ml/L ethephon) and T7 (4
ml/L ethephon), respectively and these were at par with each other.
4.3.2.4.1.6 Overall acceptability score
The analysed data presented in Figure 4.91 showed significant differences (p ≤ 0.05)
regarding the effects of chemical treatments while cultivars and interaction were found
non-significant for overall acceptability scores in fruits at tamar stage (Figure 4.3.2.4.1.6).
Maximum overall acceptability score of 4.83 was marked by the panellist in the fruits
those were treated with 3% acetic acid (T3) than all other treatments. Meanwhile,
minimum overall acceptability scores indexes of 1.16, 1.33 and 1.83 were ranked by the
panellists in the fruits of T1 (control), T9 (dipping in 3% acetic acid+ 3% NaCl+4 ml/L
ethephon) and T7 (4 ml/L ethephon).
In general, panellists favoured the fruits of both Hillawi and Khadrawi cultivars those
were dipped in 3% acetic acid (T3) after incubation at 40±1oC for 72h as compared to the
fruits of all other chemical treatments.
Figure 4.86 Effects of different chemicals on colour score of Hillawi and Khadrawi date
palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in % acetic acid+2%
NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3% NaCl+4 ml/L
ethephon)
0
1
2
3
4
5
T1 T2 T3 T4 T5 T6 T7 T8 T9
Co
lou
r sc
ore
Hillawi Khadrawi
159
Figure 4.87 Effects of different chemicals on taste score of Hillawi and Khadrawi date
palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in % acetic acid+2%
NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3% NaCl+4 ml/L
ethephon)
Figure 4.88 Effects of different chemicals on texture score of Hillawi and Khadrawi
date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in % acetic acid+2%
NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3% NaCl+4 ml/L
ethephon)
0
1
2
3
4
5
T1 T2 T3 T4 T5 T6 T7 T8 T9
Ta
ste
sco
re
Hillawi Khadrawi
0
1
2
3
4
5
6
T1 T2 T3 T4 T5 T6 T7 T8 T9
Tex
ture
sco
re
Hillawi Khadrawi
160
Figure 4.89 Effects of different chemicals on firmness score of Hillawi and Khadrawi
date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in % acetic acid+2%
NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3% NaCl+4 ml/L
ethephon)
Figure 4.90 Effects of different chemicals on astringency score of Hillawi and Khadrawi
date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in % acetic acid+2%
NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3% NaCl+4 ml/L
ethephon)
0
1
2
3
4
5
6
T1 T2 T3 T4 T5 T6 T7 T8 T9
Fir
mn
ess
sco
re
Hillawi Khadrawi
0
1
2
3
4
5
6
T1 T2 T3 T4 T5 T6 T7 T8 T9
Ast
rin
gen
cy s
core
Hillawi Khadrawi
161
Figure 4.91 Effects of different chemicals on astringency score of Hillawi and Khadrawi
date palm fruit after incubation at 40±1oC for 72 h ± S.E.
(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,
T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L
ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in % acetic acid+2%
NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3% NaCl+4 ml/L
ethephon)
0
1
2
3
4
5
6
T1 T2 T3 T4 T5 T6 T7 T8 T9
Ov
era
ll a
ccep
tab
ilit
y s
core
Hillawi Khadrawi
162
4.3.2 (1, 2) Discussion
Climate is one of the main stay in date palm industry, which drastically affects its
cultivation, production, processing and quality. Monsoon rains at rutab and tamar fruit
ripening stages are threatening issues for date palm growers and processors. According to
an estimate about 60% of the dates are destroyed due these rains. In the country there is
no trend to process or cure the fruit of Hillawi and Khadrawi cultivars and whole the fruit
is consumed at khalal stage as fresh dates or convert into fully dried form (Chohara) with
less economic value. However, if these dates are artificially processed or cured into semi
dry form or as soft dates by harvesting the fruit at khalal stage before the onset of
monsoon rains, losses occurred due to these rains can be minimized and good return
could be earned. The present study therefore was conducted to explore or find out the
various ways or means to artificially ripe the date fruit by harvesting at early stage of
maturity (khalal stage) to avoid the risk of monsoon rains. This whole study was
comprised of three parts which are discussed in separate paragraphs as follows.
Heat treatments of fruits and vegetables can be done by means of hot water, vapor, or hot
dry air. Recently, extensive global concern in the heat treatment for maintaining the food
quality and diseases has been shown in literatures. Water is the most efficient and
preferred medium in many of the applications than the others. Hot water treatment has
some advantages which include: comparatively simple to use, short treatment time,
consistent handling of fruits and water temperatures, and killing of skin-borne decay
causing agents with economic advantage as it is cheap as compared to other heat
application methods (Fallik et al., 1999; Garcia-Jimenez et al., 2004). Higher temperature
exposure in agricultural products alters the various physiological processes such as heat
shock proteins transcripts and different level of proteins in such type of products (Lurie,
1998).
Fruit ripening is a natural process which involves a number of physiological and chemical
changes in which fruits gradually becomes sweet in taste, more coloured, and becomes
softer and palatable. However, with the progression of science and technology, numerous
artificial methods have been observed for fruit ripening generally to fulfill the demands of
consumers’ and other economic factors. In date palm, the need of artificial ripening is
encountered to avoid the risk of monsoon rains at the time of fruit harvesting or ripening.
The present study therefore was carried out to explore the role of different chemicals on
fruit ripening behavior and quality of Hillawi and Khadrawi date palm cultivars.
163
Different types of chemicals or ripening agents are available which possibly disrupt the
epidermal cells and the protoplasm, thereby releasing and activating the enzymes.
Ripening by involvement of enzymes like invertase, polygalacturonase, cellulase, pectin
esterase and polyphenol oxidases, causes the disturbance in structural parts e.g. pectin and
cellulose that hold cells together, to become soluble, and the tannins to precipitate. As a
result, this facilitates the ripening process of fruits from khalal to tamar, which involve;
precipitating out of tannins, increasing small sugars causing sweetness, texture softening
and introducing changes in fruit colour and other ripening-associated quality parameters.
The extent of modification varies which depends on the stage of fruit maturity and
environmental factors that are responsible for the ripening/curing of the fruits (Shamshiri,
and Rahemi, 1999).
In the present study, hot water treatments significantly affected the fruit physical,
biochemical and phytonutritional traits in date fruits at tamar stage as compared to fruits
those were untreated in both date palm cultivars. Both cultivars showed variable response
regarding the effects of hot water treatments. Hot water treatments for 3 and 5 min at
65oC significantly accelerated the fruit ripening processes and produced more uniformly
ripe fruits as compared to untreated fruit in Hillawi and Khadrawi, respectively. In date
the actual mechanism by which hot water treatments accelerated the fruit ripening
processes in not yet known but it might be due to increased rate of respiration, ethylene
synthesis and formation of cell wall degrading enzymes. These findings are supported by
different coworkers who reported that heat treatments significantly affects the various
ripening processes such as fruit colour (Cheng et al, 1988; Tian et al., 1996), ethylene
production (Ketsa et al., 1999), rate of respiration (Inaba and Chachin, 1988), firmness of
fruits, breakdown of cell wall (Lurie and Nussinovich, 1996) and formation of different
volatile compounds (McDonald et al, 1999). Our results are in agreement with
Shahnawaz et al. (2012) who reported that in mango hot water treated fruits ripened
earlier as compared to the fruits those were without hot water treatments with higher
scores of organoleptic properties marked by the panellists. The results are also supported
by findings of Jacobi et al., (2001) who reported that heat treatment accelerates the
yellowing of the mango fruit skin and also promotes the uniformity in skin colour and in
most cultivars fruit becomes softer. The actual mechanism by which heat treatment
accelerated date palm fruit ripening is not yet known but it has been hypothesized that it
is associated with increased synthesis of carotenoid, degradation of chlorophyll and
synthesis of cell wall degrading enzymes. Fruits those were treated with higher
164
temperature of 7 min duration at 65oC showed gradual increase in weight loss, reduced
moisture contents with lower fruit flesh and pit weights as compared to fruits those were
treated in hot water for short duration. These findings are supported by Lurie and Klein
(1990) who reported that the heat treatments triggered the increase in respiration rate and
a significant amount of organic acids were used as a substrate during respiration and
metabolic processes.
In the present study, different chemicals (acetic acid, NaCl, ethephon) significantly
affected the ripening processes and quality of both date palm cultivars as compared to
untreated fruits. Different chemicals such as 3% acetic acid and 2% acetic acid showed
better results for obtaining the higher uniform fruit ripening index with good quality and
sensorial properties as compared to fruits those were treated with other chemicals. These
results are supported by Saleem et al. (2005) who reported that acetic acid and sodium
chloride are more effective for uniform fruit ripening acceleration, as these chemicals
inclined to makes ripening by triggering the modifications in the selected quality
characters in Dhakki date palm. They reported that that sodium chloride is more effective
for inducing ripening but our results are opposite to them that acetic acid is more effective
for uniform ripening and good quality fruits in Hillawi and Khadrawi date palm. These
results are in agreement with Tafti and Fooladi (2006) who postulated that treatment of
‘Mozafati’ date fruits with acetic acid at the end of khalal stage after incubating at 38-
40oC for 3-5 days is the more effective and economical method for artificial ripening of
the fruit. These results are also correlated with Haq (1990) who reported that curing of
‘Zahidi’ dates with acetic acid and NaCl alone or in combination showed significantly
superior results by affecting the early ripening of the fruit and make the fruit soft over all
other treatments. The possible reason for ripening acceleration in date fruits due to such
type of chemicals might be that polygalacturonase and cellulase are the ripening enzymes
which are absent at immature stage but their activity was increased during ripening
(Hasegawa et al., 1969; Saleem et al., 2002). Untreated fruits do not ripe properly and
most of the fruits remained immature and goes to shrivelling and puffiness with higher
fruit weight loss, less moisture contents and less fruit flesh weight with poor quality as
compared to fruits those were treated with different chemicals. It is because; unripe fruits
are not able to develop ripening processes properly as in chemical treated fruits.
Hot water treatments significantly affected the fruit quality and organoleptic attributes in
both date palm cultivars. Hot water treatments for 3 and 5 min in Hillawi and Khadrawi
produced good quality fruits at tamar stage in terms of higher TSS, sugars, phytonutrients
165
and organoleptic properties than longer duration of 7 min, respectively. These findings
are supported by Wall (2004) who reported that hot water exposure time had a greater
effect than the water temperature during banana fruit ripening. It is because; the
conversion of starch into sugars might be reduced at higher temperatures and longer
exposure times. While levels of titratable acidity and ascorbic acid were decreased in
fruits those were treated with hot water in both cultivars as compared to untreated fruits.
The decrease in acidity and ascorbic acid levels might be due to the oxidative destruction
of biochemical constituents during thermal processing when date fruits exposed to hot
water treatments as compared to untreated fruits. These findings were also confirmed by
Pudmini and Prabha (1997) and Thomas and Oke (1980) who reported that hot water
treatments reduced the levels of acidity and ascorbic acid contents during the progression
of fruit ripening. The increase in total soluble solids might be due to the alteration in cell
wall structure and break down of complex carbohydrates into simple sugars whereas slow
changes observed in TSS of control fruit samples (Aina 1990; Rajwana et al., 2010).
Similarly, the increase in total sugars level could be attributed mainly due to the
breakdown of starch into simple sugars during ripening process along with a proportional
increase in total sugars which were attributed to the increased activity of amylase and
other enzymes converted into sucrose, glucose and fructose (Aina 1990; Rajwana et al.,
2010). These results can be correlated with the findings of Srinivasa et al. (2002) and
Kudachikar et al. (2001) who reported that hot water treatments effectively increased the
total sugar contents in mango and fewer changes occurred in control fruits. These results
were also supported by different co-workers Aina (1990) and Jabbar et al. (2010) who
reported that sugar contents were remained higher in hot water treated fruits as compared
to untreated fruits throughout the ripening process.
The fruit quality composition of both cultivars was significantly improved in chemical
treated fruits as compared to untreated fruits. The best quality fruits were obtained from
3% acetic acid and 2% acetic acid than other chemical treatments in both cultivars. Total
soluble solids, sugars, phytonutritional parameters and organoleptic properties were
significantly improved in acetic acid treated fruits. These findings are supported by Mirza
and Meraj-ud-Din (1988) who treated the fruits of ‘Dhakki’ and ‘Basra’ cultivars at
khalal stage with 3% brine solution, 0.25% acetic acid and 0.25% citric acid solution for 5
min and found that different chemical treatments enhanced the fruit ripening process
significantly with better fruit quality. Our results regarding the TSS are in line with Naik
et al. (1993) who reported that increases in TSS during the ripening was mainly due to
166
break down of polysaccharides into simple sugars thereby causing a rise in total soluble
solids. These findings were also supported by different co-workers (Zaid, 2002; Saleem et
al., 2005; Awad, 2007) they reported that significant increase in total soluble solids might
be due to the higher evaporation of water contents in the incubator during the progression
of ripening (Rouhani and Bassiri, 1977; Zaid, 2002; Saleem et al., 2005; Awad, 2007).
These results are also supported by Farahnaky and Afshari-Jouybari (2011) who reported
that fruits those were treated with hot acetic acid solution showed slightly increase in TSS
contents in Mazafati date palm cultivar as compared to untreated fruits. The reduction of
TSS in untreated fruits was probably due to the slow rate of respiration and metabolic
activities, hence retarding the ripening process. These findings were supported by Rohani
et al. (1997) they reported that the slow rate of respiration also slows down the synthesis
and use of metabolites resulting in lower amounts of total soluble solids due to the slower
changes from carbohydrates to sugars. However, the effects of such chemicals on
phytonutrients are not reported in the literature. In our study, the phytonutrients were
significantly affected by different chemicals. It is because, fruits those were treated with
chemicals showed progressive ripening and fruit becomes softer. This might be due to
changes in phenolic compounds and antioxidants activities which affect the fruit quality
composition in date fruits during ripening. However, this mechanism is still unknown in
date fruits and also in other fruits. However, further research is needed to confirm these
changes to understand the actual mechanism.
Hot water treatments at 65oC for duration of 3 and 5 min in Hillawi and Khadrawi
showed good results to accelerate the fruit ripening, uniformity and good quality
attributes, respectively. This research work has a great significance for the date growers
who could harvest the fruit at khalal stage to avoid the risk of monsoon rains and
artificially ripe the fruits by adopting hot water technologies. The results of the current
experiment have a great practical application for the date growers who can artificially ripe
the date fruit by harvesting at khalal stage with the treatments of 3% acetic acid and can
avoid the risk of monsoon rains. In the meantime, uniformity in ripening is an extra
benefit which can be achieved by adopting these technologies and it provides more
economic return to the growers.
167
4.3.3 (1, 2) Conclusion
Hot water treatment (HWT) is an effective and low cast technology to accelerate the date
fruit ripening artificially. Hot water exposures for 3 and 5 min at 65oC in Hillawi and
Khadrawi cultivars showed best results to reduce the fruit ripening period up to 6 days
and produced uniformly ripened fruits (73.33 and 81.66%) with better quality and higher
acceptability of organoleptic scores marked by the panellists as compared to untreated
fruits. Acetic acid (3%) significantly affected the fruit ripening behaviour and quality
composition as compared to other treatments after incubation at 40 ± 1oC for 72 h in
Hillawi and Khadrawi date palm cultivars. Acetic acid (3%) showed higher uniform
ripening index of 64.24% with higher total soluble solids concentration, sugars, total
phenolics, total flavonoids, total antioxidants and organoleptic properties after incubation
at 40±1oC for 72 h. Artificial date fruit ripening reduced the losses occurred due to rains
by harvesting the fruit at early maturity stage (khalal stage).
168
4.4. Study-4 Sun-drying techniques (SDTs) affected the fruit
quality attributes of dates picked at rutab stage cv.
Hillawi.
4.4.1 Results
4.4.1.1 Fruit weight loss (%)
The analysed data presented in Figure 4.92 showed significant differences (p ≤ 0.05)
regarding the effects of sun-drying techniques on weight loss in the fruits of Hillawi
cultivars at tamar stage. Different types of sun-drying techniques significantly affected
the fruit weight loss of Hillawi date palm. Minimum weight loss of 18.73% was recorded
in the fruits of SDT4 (DSE with removal in baskets and covered during night) and these
were at par with the fruits of SDT3 (DSE and removal in baskets during night) where loss
in weight was 22.66% followed by SDT5 (DSE and removal with mats during night) and
SDT2 (DSE and covering with polythene sheet during night) where losses in weights
were 27.47 and 28.17%, respectively and these were at par with each other. While,
maximum weight loss of 47.80% was noted in the control fruits of SDT1 (DSE without
covering and removal during night).
4.4.1.2 Fruit moisture content (%)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of sun-
drying techniques on moisture content in the fruits of Hillawi cultivar at tamar stage
(Figure 4.93). Different sun-drying techniques significantly affected the fruit moisture
contents of Hillawi date palm. Maximum level of moisture contents (24.13 and 21.06%)
were recorded in the fruits of SD4 (DSE with removal in baskets and covered during
night) and SDT3 (DSE and removal in baskets during night), respectively and these were
at par with each other. Whereas, lower level of moisture contents (13.91%) was noted in
the fruits of SDT1 (DSE without covering and removal during night).
4.4.1.3 Total soluble solids concentration (oBrix)
The effects of sun-drying techniques showed statistically significant differences for total
soluble solids contents in the fruits of Hillawi at tamar stage (Figure 4.94). Higher
amounts of total soluble solids contents (11.09 oBrix) was noted in the fruits of SD4 (DSE
with removal in baskets and covered during night) followed by SDT3 (DSE and removal
in baskets during night) and SDT5 (DSE and removal with mats during night) where total
soluble solids contents were 9.39 and 8.43 oBrix, respectively and these were at par with
169
each other. While, lower total soluble solids contents of 6.21 oBrix were noted in the
fruits of SD1 (DSE without covering and removal during night) and these were at par
with the fruits of SD2 (DSE and covering with polythene sheet during night) where total
soluble solids contents of 7.28 oBrix were recorded.
4.4.1.4 Total titratable acidity (%)
Total titratable acidity in the fruits at tamar stage showed significant differences at p ≤
0.05 regarding the effects of sun-drying techniques (Figure 4.95). Different types of sun-
drying techniques significantly affected the total titratable acidity of Hillawi fruits. Lower
total titratable acidity of 6.21% was noted in the fruits of SD4 (DSE with removal in
baskets and covered during night) than the fruits of all other treatments. While, higher
total titratable acidity level of 0.263% was recorded in the fruits of SD1 (DSE without
covering and removal during night).
4.4.1.5 Reducing sugars (%)
The analysed data presented in Figure 4.96 showed statistically significant differences (p
≤ 0.05) regarding the effects of sun-drying techniques on the reducing sugars of Hillawi
fruit at tamar stage. Different sun-drying techniques positively affected the reducing
sugars of Hillawi fruit. Higher amounts of reducing sugars (26.46%) were recorded in the
fruits of SD4 (DSE with removal in baskets and covered during night) followed by SD3
(DSE and removal in baskets during night) and SD5 (DSE and removal with mats during
night) where reducing sugars were 47.24 and 44.21%, respectively. Whereas, lower levels
of reducing sugars (26.46%) were noted in the fruit of SD1 (DSE without covering and
removal during night).
4.4.1.6 Total sugars (%)
Statistically significant results were found at p ≤ 0.05 regarding the effects of sun-drying
techniques on the total sugars in fruit at tamar stage (Figure 4.97). Different types of sun-
drying techniques significantly affected the total sugars of Hillawi date palm. Maximum
amounts of total sugars of 69.39% were recorded in the fruits of SD4 (DSE with removal
in baskets and covered during night) followed by SD3 (DSE and removal in baskets
during night) where total sugars of 62.10% were noted as compared to the fruit of all
other sun-drying treatments. Whereas, minimum amounts of total sugars (32.88%) were
noted in the fruit of SD1 (DSE without covering and removal during night).
170
Figure 4.92 Effects of sun-drying techniques on weight loss (%) in the fruit of Hillawi
cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2 =
DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
Figure 4.93 Effects of sun-drying techniques on moisture content (%) in the fruit of
Hillawi cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2 =
DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
0
10
20
30
40
50
60
SDT1 SDT2 SDT3 SDT4 SDT5
Wei
gh
t lo
ss (
%)
0
5
10
15
20
25
30
SDT1 SDT2 SDT3 SDT4 SDT5
Mo
istu
re c
on
ten
t (%
)
171
Figure 4.94 Effects of sun-drying techniques on total soluble solids concentration (%) in
the fruits of Hillawi cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2 =
DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
Figure 4.95 Effects of sun-drying techniques on total titratable acidity (%) in the fruits of
Hillawi cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2 =
DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
0
2
4
6
8
10
12
14
SDT1 SDT2 SDT3 SDT4 SDT5
TS
S (
oB
rix
)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
SDT1 SDT2 SDT3 SDT4 SDT5
TA
(%
)
172
Figure 4.96 Effects of sun-drying techniques on reducing sugars (%) in the fruits of
Hillawi cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2 =
DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
Figure 4.97 Effects of sun-drying techniques on total sugars (%) in the fruits of Hillawi
cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2 =
DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
0
10
20
30
40
50
60
SDT1 SDT2 SDT3 SDT4 SDT5
Red
ucin
g s
ug
ars
(%)
0
10
20
30
40
50
60
70
80
SDT1 SDT2 SDT3 SDT4 SDT5
To
tal
sug
ars
(%)
173
4.4.1.7 Total phenolics (mg GAE/100 g)
The analysed data presented in Figure 4.98 showed significant differences (p ≤ 0.05)
regarding the effects of sun-drying techniques on total phenolics in the fruit of Hillawi
cultivar at tamar stage. Higher amounts of total phenolic contents (224.28 mg GAE/100
g) were recorded in the fruit of SD4 (DSE with removal in baskets and covered during
night) followed by SDT3 (DSE and removal in baskets during night) and SDT5 (DSE and
removal with mats during night) where total phenolics were 189.88 and 181.50 mg
GAE/100 g, respectively. Whereas, lower amounts of total phenolics of 166.80 mg
GAE/100 g were noted in the fruit of SDT1 (DSE without covering and removal during
night).
4.4.1.8 Total flavonoids (mg CEQ/100 g)
Statistically significant differences were found at p ≤ 0.05 regarding the effects of sun-
drying techniques on total flavonoids in the fruit of Hillawi cultivar at tamar stage (Figure
4.99). Maximum amounts of total flavonoids (34.31 mg CEQ/100 g) were noted in the
fruits of SD4 (DSE with removal in baskets and covered during night) followed by SDT3
(DSE and removal in baskets during night) where total flavonoids of 29.86 mg CEQ/100
g were recorded. While, lower amounts of total flavonoids of 22.54 mg CEQ/100 g were
noted in the fruit of SDT1 (DSE without covering and removal during night).
4.4.1.9 Total antioxidants (%)
Total antioxidants activities in fruit at tamar stage showed significant differences (p ≤
0.05) regarding the effects of sun-drying techniques (Figure 4.100). Higher total
antioxidants activities of 72.20% were noted in the fruits of SD4 (DSE with removal in
baskets and covered during night) followed by SDT3 (DSE and removal in baskets during
night) and SDT5 (DSE and removal with mats during night) where total antioxidants
activities were 61.21 and 51.31%, respectively and these were at par with each other.
Whereas, lower total antioxidants activities of 32.35% were recorded in the fruits of
SDT1 (DSE without covering and removal during night).
4.4.1.10 Total tannins (%)
The effects of sun-drying techniques showed significant differences (p ≤ 0.05) for total
tannins in Hillawi fruit at tamar stage (Figure 4.101). Lower total tannins of 0.143% were
recorded in the fruit of SD4 (DSE with removal in baskets and covered during night)
followed by SDT3 (DSE and removal in baskets during night) where total tannin contents
of 0.210% were noted. Whereas, higher amounts of total tannins of 0.323% were
recorded in the fruit of SDT1 (DSE without covering and removal during night).
174
Figure 4.98 Effects of sun-drying techniques on total phenolics (mg GAE/100 g) in the
fruits of Hillawi cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2 =
DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
Figure 4.99 Effects of sun-drying techniques on total flavonoids (mg CEQ/100 g) in the
fruits of Hillawi cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2 =
DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
0
50
100
150
200
250
SDT1 SDT2 SDT3 SDT4 SDT5
TP
C (
mg
GA
E/1
00
g)
0
5
10
15
20
25
30
35
40
SDT1 SDT2 SDT3 SDT4 SDT5
TF
C (
mg
CE
Q/1
00
g)
175
Figure 4.100 Effects of sun-drying techniques on total antioxidants (%) in the fruits of
Hillawi cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2
= DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
Figure 4.101 Effects of sun-drying techniques on total tannins (%) in the fruits of Hillawi
cultivar analysed at tamar stage ± S.E.
(SDT1 = Control (DSE without covering and removal during night), SDT2
= DSE and covering with polythene sheet during night, SDT3 = DSE and
removal in baskets during night, SDT4 = DSE with removal in baskets and
covered during night, SDT5 = DSE and removal with mats during night
(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)
0
10
20
30
40
50
60
70
80
SDT1 SDT2 SDT3 SDT4 SDT5
To
tal
an
tio
xid
an
ts (
%)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
SDT1 SDT2 SDT3 SDT4 SDT5
To
tal
tan
nin
s (%
)
176
4.4.2 Discussion
Dates are an important fruit crop of Pakistan and its consumption is started at khalal stage
but if these are consumed at tamar stage (dried) then its return can be increased up to four
fold. Hillawi is the main cultured variety of Punjab and almost consumed at khalal stage.
Hillawi is the prime cultivar and commercially grown in Punjab, Pakistan and its ripening
period starts from mid-July to August which is a peak monsoon period. The fruit of
Hillawi is completely harvested and consumed at khalal stage with less economic worth
and there is no trend to process or cure the fruit due to the occurrence of monsoon rains.
However, if the fruit is harvested at its right maturity stage (rutab) and properly
processed/cured by using proper sun drying techniques (SDTs), fruit can be saved for
future consumption with good economic value.
Drying is an ancient process of food preservation that works by removing water from the
food, which inhibits enzymatic degradation and limits microbial growth (Ratti, 2001). It
is the most wide spread and energy-consuming food preservation process (Ratti, 2001).
Different methods of drying have been developed for foods and each method has its own
characteristics. Sun-drying is a low cast technology which reduces the post-harvest losses
in developing countries. Drying of fresh dates is necessary because it contains high
moisture (about 60%) which limits the shelf life. In sun-drying water is usually removed
by evaporation. Mature date fruits are allowed to partially dry on the trees before they are
harvested and further sun dried to enhance their keeping quality and storage. However,
problems associated with sun drying are well documented (Guine and Castro, 2002;
Doymaz, 2004; Doymaz, 2005). During dehydration, irreversible burst and discoloration
occur to the exposed commodity resulting in loss of integrity due to capillaries shrinkage
with less hydrophilic properties (Lewicki, 1998). Sun-drying allows flavours to
concentrate, prevents the loss of volatile compounds and unwanted caramelization of
natural sugars which may result from using other drying methods (Valley, 2000). Sun-
drying enhances good initial color and texture, as well as translucency and sheen (Mrak et
al., 1946).
Fruit weight loss and moisture contents were greatly affected by various sun drying
techniques. Maximum loss in fruit weight (47.80%) was recorded in control (DSE
without covering and removal during night) whereas minimum fruit weight loss (18.73%)
was observed in SDT4 (DSE with removal in baskets and covered during night).
Maximum reduction in moisture (13.91%) was noted in control while minimum reduction
177
(24.13%) was recorded in SDT4. Weight loss from fresh food commodity is mainly due
to transpiration and respiration. In transpiration water is lost due to differences in water
vapour pressure in the atmosphere and the transpiring surface. Respiration results weight
reduction because a carbon atom is lost from the fruit each time a carbon-dioxide
molecule is produced from an absorbed oxygen molecule and evolved into the
atmosphere (Bhowmik and Pan, 1992). Fruit weight loss of the fresh product can
influence the economic returns. It was observed that continuous open sun drying caused
excessive weight loss with poor quality fruit as compared to other modified sun drying
techniques. In developing countries, one of the main purposes of sun drying is to reduce
the postharvest losses by lowering the internal water contents to an optimum level
(Olorunda et al., 1990).
Sugars in date fruits are the most important constituents as they provide a rich and quick
source of energy to human beings. Sun drying techniques significantly affected the total
soluble solids (TSS) in Hillawi fruit. Minimum TSS value (6.21 oBrix) was noted in
control while higher value (11.09 oBrix) was recorded in SDT4. Higher fruit acidity
(0.263%) was recorded in control whereas lower acidity level (0.130%) was recorded in
treatment SDT4. Higher value of total sugar (69.39%) was recorded in SDT4 while
SDT1 gave minimum total sugar contents of 32.88%. Maximum reducing sugar content
(51.47%) was noted in SDT4 followed by SDT3 and SDT5 whereas minimum value was
recorded in SDT1 which was 26.46%. Solar radiation and temperature have a great
influence on fruit sugar accumulation. The results regarding sugar contents were
significantly affected by sun drying techniques. Fruit sugar content is a variable
multigenic trait which is greatly affected under varied environmental conditions (Kader,
1986). The open sun drying caused a heavy loss of sugar contents as compared to those
fruits which were removed during night time. High temperature led to increase the TSS
due to changes in carbohydrate biosynthetic enzymes activity (Walker and Ho, 1977), and
increased transpiration (Gautier et al., 2008). Postharvest practices such as timing of the
harvest, handling techniques, and storage conditions can alter the fruit sugar profiling
(Kader, 1986). In SDT4 the improvement in fruit quality might be due to presence of all
day’s heat which reduces the excessive fruit weight loss by maintaining the internal fruit
water contents, color and other quality related characters.
Date fruit is an important source of phytonutrients that are responsible for sustaining the
human life; they have been recognized as containing properties for disease prevention.
Different types of sun drying techniques significantly affected the phytonutritional
178
composition of the Hillawi fruit. Higher total phenolic contents were measured in SDT4
which were 224.28 mg GAE/100 g and lower TPC (166.80 mg GAE/100 g) were
recorded in SDT1. Higher antioxidant activity was recorded in SDT4 with greater
scavenging activity of 72.20% DPPH inhibition while lower antioxidant activity was
observed in SDT1 with scavenging activity of 32.35% DPPH inhibition. Maximum total
flavonoids contents (TFC) were recorded in SDT4 which were 34.31 mg CEQ/100 g.
Lower TFC was observed in SDT1 which gave the value of 22.54 mg CEQ/100 g.
Higher level of total tannin contents (0.323%) were noted in control while minimum were
recorded in SDT4 which were 0.143% followed by SDT3 (0.210%) and SDT5 (0.246%).
Our results are also in line with (Walker and Ho, 1977) who reported that appropriate
sun-drying methods allows food flavours to concentrate, preventing the loss of volatile
compounds and unwanted caramelization of natural sugars and prevents the undesirable
browning color. These results are also in agreement with (Mrak et al., 1946) who
revealed that sun-drying enhances the good initial color and texture, as well as
translucency and sheen of the tested food commodity. In our study phenolic compounds
were also significantly affected by various sun drying techniques. These results are
supported by findings of (Al Farsi et al., 2005) they reported that sun drying significantly
increased phenolic contents in fruits that could be due to the degradation of tannins by
heat, destruction of anthocyanin and maturation of enzymes during the drying process
(Maillard and Berset, 1995).
4.4.3 Conclusion
The obtained results indicate that sun drying techniques (SDTs) significantly affected the
fruit physical and quality characters in ‘Hillawi’ date palm. Among all the tested sun
drying techniques, SDT4 (DSE with removal in baskets and covered during night) proved
good which plays a very effective role in reducing the excessive fruit weight loss by
maintaining the fruit moisture contents to an optimum level and other compositional
changes such as TSS, acidity, total sugar, reducing sugar, total phenolics, total antioxidant
activity, total flavonoids and total tannin contents.
179
Harvesting of rutab dates Drying on mat
Removal in baskets After removal in baskets
Covered in baskets with newspaper Dates after washing
180
Dates packed in box Dates packed in box with labelling
Slide-4.3: Different steps involved in the processing of soft Hillawi dates by sun-
drying techniques.
181
Chapter-5
General discussion: Conclusions: Recommendations
5.1 General discussion
Globally, date palm is one of the most extensively cultivated fruit crops in dry regions
and playing an important role in the history of mankind since ancient times. The date
palm is particularly significant in scorched areas and the economic and social life of the
peoples living in such areas is fully dependent on date’s income. The nutritional value of
date fruit consumed either fresh or in the form of many other derived by-products has a
unique global importance. Climate is one of the main stay in date palm industry, which
drastically affects its cultivation, production, processing and quality. In Pakistan, the peak
production period of dates begins during hot months of July and August. But
unfortunately, monsoon rains occurs during these months which is a real threat for date
fruit crop because these rains can destroy up to 60% date fruit.
Fruit ripening is an irreversible phenomenon which involves a number of physical,
biochemical and organoleptic changes. These changes are interdependent on each other
and after the successful completion of these changes fruit becomes edible with desirable
quality traits. Exogenous applications of some chemicals are capable to alter these
changes by accelerating the rate of respiration, starch hydrolysis, softening, and flavour
and colour development. A very little work has been reported regarding the on-tree and
off-tree fruit ripening acceleration and few references are available in the literature where
efforts have been made to accelerate the fruit ripening on the tree and after harvest by
adopting different ways or means.
The foremost goal of this whole study was to minimize the losses occurs due to monsoon
rains at the time of fruit harvesting or ripening in Hillawi and Khadrawi date palm
cultivars. This study was comprised of four parts: in first part the effectiveness of
ethephon to accelerate the fruit ripening and quality was studied at two different fruit
maturity stages (final kimri and early khalal). Second part of the study comprised of
different strands thinning practices to accelerate the fruit maturation period and quality.
Third part of the study consists of two experiments: first one was to evaluate the role of
hot water treatments on ripening and fruit quality of date palm. In second one the role of
different chemicals on the ripening behaviour and fruit quality of date palm was
182
investigated. In the fourth and last study, effects of different sun-drying techniques on the
fruit quality characteristics of Hillawi date palm were studied.
In first part of the study ethephon was applied at final kimri and early khalal fruit maturity
stages by two different methods (spray and injection). Foliar spray of ethephon applied at
both fruit maturity stages (final kimri and early khalal) showed better results as compared
to injection application method in both date palm cultivars. Foliar application of ethephon
@ 6 ml/L and 4 ml/L at final kimri and early khalal stages accelerated the fruit ripening
period by about 13 and 6 days from final kimri to rutab stage, respectively with higher
rutab fruit yield per bunch and maximum uniform fruit ripening index. The increase in
rutab fruit yield per bunch and uniform fruit ripening index were mainly due to the action
of ethylene that generates from ethephon application. Current results regarding the fruit
physical traits (fruit weight, fruit length, fruit width, fruit flesh weight, fruit pit weight)
showed statistically non-significant (p ≥ 0.05) differences against ethephon application
while both date palm cultivars differ significantly and these differences were mainly due
to the genetic character of both cultivars. Foliar spray (6 ml/L and 4 ml/L) at final kimri
and early khalal fruit stages showed more reduction in moisture content in both cultivars.
This decline in fruit moisture content was might be due to the progression of ripening
process due the action of ethylene. Fruit treated with foliar spray (4 ml/L and 2 ml/L) at
final kimri and early khalal stages showed higher total soluble solids concentration in
both cultivars. This increase in total soluble solids concentration in ethephon treated fruits
is might be due to the rise of sugar content which mostly depends upon the conversion of
starch on hydrolysis during the progression of ripening. Foliar application of ethephon (4
ml/L and 2 ml/L) at final kimri and early khalal fruit stages significantly decreased the
level of fruit acidity in both date palm cultivars during both years. The reduction in fruit
acidity indicated that ethephon promoted the ripening process and lowered down the
acidity level due to the completion of ripening processes. Foliar spray of ethephon (4
ml/L and 2 ml/L) at final kimri and early khalal stages significantly increased the ascorbic
acid contents in treated fruits as compared to control fruits. The increase in ascorbic acid
in ethephon treated fruit might be due to quick ripening process and fruits have less time
to loss the ascorbic acid. Foliar spray of ethephon (4 ml/L) at final kimri stage produced
higher sugars in both date palm cultivars. More accumulation of phytonutrients was
observed in ethephon-treated fruit as compared to untreated one in both date palm
cultivars. Ethephon application (4 ml/L) showed higher amounts of total phenolics, total
flavonoids and total antioxidants activities with lower level of total tannins in both
183
cultivars. However, ethephon application at early khalal stage did not show significant
variation except total tannin contents in the fruits of both cultivars. This reduction in fruit
astringency might be due to the coagulation of tannin cells into insoluble tannins in both
cultivars. In general, method of ethephon application showed great variation in their
response as ethephon applied by foliar spray performed better as compared to injection
application in both date palm cultivars. It is because foliar spray might have a direct
contact with fruits cuticle layer that fasten up the respiration process and fruits reached at
maturity within shorter time. Whereas, ethephon application by injection could not
achieved quick and fast response that might be due to its slow translocation from the
peduncle to individual fruit strands.
Cluster thinning has an important role in plants to induct physiological adjustments by
improving the kinetics of fruits maturation. It is because thinning improves the sanitary
conditions under the canopy and allows more light and fresh air penetration in the
remaining fruit clusters (Smithyman et al., 1998). In the current study, strands thinning
significantly reduced the fruits maturation period as compared to fruit where no thinning
was applied in both date palm cultivars. Strands thinning intensity @ 30% RCS + 30%
STT and 30% RCS alone accelerated the fruit maturity processes and shortened the
period by about 10 days from early kimri to rutab stage. Strands thinning intensity @
30% RCS + 30% STT and 30% RCS alone showed higher rutab fruit yield per bunch and
greater uniform fruit ripening index in both the date palm cultivars. It is due to the
involvement of more light penetration and air circulation within the fruit bunches which
might leads to fast and uniformly ripe fruits. It is because fruits received nutrients and
water from the main stem through peduncle for the development of tissue or to gain
proper size. Strands thinning intensity (30% RCS + 30% STT) and (30% RCS alone)
significantly improved the fruit physical traits such as fruit weight, fruit length, fruit
width and flesh weight in both date palm cultivars. The reasons are same as explained
above but some other can also strengthen these reasons. Sun light exposure is also
important to regulate the metabolism of carbon and assimilates in young growing fruits.
In contrast, control fruits (without thinning) had less light exposure due to high density
that leads the reduced sink strength and fruits could not develop their growth properly.
Strands thinning intensity (30% RCS + 30% STT) and (30% RCS alone) showed higher
total soluble solids concentration, ascorbic acid, sugars and decreased the level of acidity
in thinned fruit as compared to fruit without thinning. Fruit phytonutrients (total
phenolics, total flavonoids and total antioxidants) were significantly improved and total
184
tannins were decreased by strands thinning treatments in both date palm cultivars during
both years. The main reason is more exposure of light due to less fruits density; it is
because light plays an important role in processes which are responsible for the
accumulation of anthocyanins and phenolic compounds (Wicks and Kliewer, 1983,
Dokoozlian and Kliewer, 1996). On the other hand, un-thinned fruits could not attain
proper return due to less availability of light or air circulation that affects the rate of
photosynthetic carbon assimilation rate (Morrison and Noble, 1990).
Hot water treatment has some advantages which include: comparatively simple to use,
short treatment time, consistent handling of fruits and water temperatures, and killing of
skin-borne decay causing agents with economic advantage as it is cheap as compared to
other heat application methods (Fallik et al., 1999; Garcia-Jimenez et al., 2004). Different
types of chemicals or ripening agents are available which possibly disrupt the epidermal
cells and the protoplasm, thereby releasing and activating the enzymes. Ripening by the
involvement of enzymes like invertase, polygalacturonase, cellulase, pectin esterase and
polyphenol oxidases, causes the disturbance in structural parts such as pectin and
cellulose that hold cells together, to become soluble, and the tannins to precipitate.
In the present study, hot water treatments significantly affected the fruit physical,
biochemical and phytonutritional traits in date fruits at tamar stage as compared to fruits
those were untreated in both date palm cultivars. Hot water treatments for 3 and 5 min at
65oC significantly accelerated the fruit ripening processes and produced more uniformly
ripe fruits as compared to untreated fruit in Hillawi and Khadrawi, respectively. In date
fruits the actual mechanism by which hot water treatments accelerated the fruit ripening
processes is still unknown but it might be due to the increased rate of respiration, ethylene
synthesis and formation of cell wall degrading enzymes. Different chemicals (acetic acid,
NaCl, ethephon) also significantly affected the ripening processes and quality of both date
palm cultivars as compared to untreated fruits. Different chemicals such as acetic acid
(3%) and acetic acid (2%) showed better results for obtaining the higher uniform fruit
ripening index with good quality and sensorial properties as compared to fruits those were
treated with other chemicals. It is because polygalacturonase and cellulase are the
ripening enzymes which remained very low or absent in immature fruits but their activity
increased during the progression of ripening (Hasegawa and Maier, 1980; Saleem et al.,
2002) so it could be possible that exogenous application of such ripening agents enhanced
the activity of these enzymes as they become active and showed desired response.
Untreated fruits do not ripe properly and most of the fruits remained immature and goes
185
to shrivelling and puffiness with higher fruit weight loss, less moisture contents and less
fruit flesh weight with poor quality as compared to fruits those were treated with different
chemicals. It is possible that untreated fruits could not initiate their desired processes due
the lack of ripening enzymes therefore due higher weight loss fruit goes to shrivelling and
puffiness.
Hot water treatments significantly affected the fruit quality and organoleptic attributes in
both date palm cultivars especially hot water treatments for 3 and 5 min in Hillawi and
Khadrawi produced good quality fruits at tamar stage in terms of higher TSS, sugars,
phytonutrients and organoleptic properties as compared to the fruits treated for longer
exposure time of 7 min. It is because the fruits treated for longer exposure of 7 min
remained in higher temperature for a long period, so due to high temperature starch could
not hydrolyse into sugars properly. The levels of titratable acidity and ascorbic acid were
decreased in the fruits treated with hot water as compared to untreated fruits in both date
palm cultivars. This decrease in acidity and ascorbic acid might be due to the degradation
of bio-chemical constituents during the fruit ripening. The fruit quality composition of
both cultivars was significantly improved in chemical treated fruit as compared to
untreated fruit. The best quality fruits were obtained from 3% acetic acid and 2% acetic
acid than other chemical treatments in both cultivars. Total soluble solids, sugars,
phytonutritional parameters and organoleptic properties were significantly improved in
acetic acid treated fruits. The phytonutrients were significantly affected by different
chemicals treatments. It is because, fruits those were treated with chemicals showed
progressive ripening and fruit becomes softer as compared to untreated fruits. This might
be due to changes in phenolic compounds and antioxidants activities during the
progression of ripening which affects the fruit quality composition during ripening.
However, this mechanism is still unknown in date fruits and also in other fruits.
Therefore, further research is needed to confirm these changes to understand the actual
mechanism. In the last study, different sun-drying techniques (SDTs) were used for the
curing of soft Hillawi dates. Sun-drying techniques significantly affected the fruit
physical and biochemical characters in Hillawi date palm. Among all the tested sun-
drying techniques, SDT4 (DSE with removal in baskets and covered during night) proved
good which plays a very effective role in reducing the excessive fruit weight loss by
maintaining the fruit moisture contents to an optimum level and other compositional
changes such as TSS, acidity, total sugar, reducing sugar, total phenolics, total
antioxidants, total flavonoids and lower level of total tannins.
186
5.2 Conclusions
1. Foliar application of ethephon (4 ml/L) at final kimri stage is an effective cultural
practice for Hillawi and Khadrawi date palm cultivars to combat the seasonal
fluctuations in the form of monsoon rains at the time of fruit harvesting and/or
ripening by accelerating the fruit maturation period about 13 days, attained
uniformity index of 60.46%, rutab fruit yield (6.29 kg) per bunch and also
improved the fruit quality composition in terms of TSS, ascorbic acid, sugars,
total phenolics, total flavonoids and total antioxidants with decreased level of
acidity and total tannins in both date palm cultivars.
2. Strands thinning intensity (30% RCS alone) resulted in 10 days early maturity and
higher yield (5.22 kg per bunch) and uniformly ripe fruits (76.28%) at rutab stage
in Hillawi and Khadrawi cultivars. The TSS, ascorbic acid, sugars (glucose,
fructose, and sucrose), total phenolics, total flavonoids and total antioxidants were
significantly improved while titratable acidity and total tannin contents were
decreased in thinned fruits. Strands thinning intensities (30% RCS alone) was the
best thinning treatment for obtaining the desired fruit quality traits as compared to
other thinning intensities.
3. Hot water exposures for 3 and 5 min at 65oC in Hillawi and Khadrawi cultivars
showed best results to reduce the fruit ripening period up to 6 days and produced
uniformly ripened fruits (73.33 and 81.66%) with better quality and higher
acceptability of organoleptic scores marked by the panellists as compared to
untreated fruits.
4. Acetic acid (3%) showed higher uniform ripening index of 64.24% with higher
levels of TSS, sugars, total phenolics, total flavonoids, total antioxidants and
organoleptic properties after incubation at 40 ± 1oC for 72 h.
5. Among different sun drying techniques, SDT4 (DSE with removal in baskets and
covered during night) proved best regarding the fruit quality composition such as
TSS, acidity, total sugar, reducing sugar, total phenolics, total antioxidants, total
flavonoids and total tannins.
5.3 Recommendations
1. Ethephon should be applied as foliar spray (4 ml/L) at final kimri stage is effective
to reduce the fruit harvesting period up to 13 days to avoid synchronization of
monsoon rains as well as improving the fruit ripening and quality of date palm.
187
2. If pesticide companies are involved to commercialize this ethylene releasing
product (ethephon) at farm level then the losses occurred due to monsoon rains
can be minimized by reducing the fruit transition period from kimri to rutab fruit
developmental stages by early harvesting and processing the fruit.
3. Growers can obtain uniformly mature and good quality fruits by adopting regular
thinning practices (30% RCS alone) as managerial approach to attain maximum
uniformity and good fruit physical, biochemical and phytochemical characters.
4. Date palm growers can artificially ripe/cure the date fruits by applying hot water
treatments for short duration (3 min for Hillawi and 5 min for Khadrawi at 65oC)
and by dipping the fruit in 3% acetic acid solution by harvesting the fruit at early
maturation phase (khalal stage) to avoid the risk of monsoon rains.
5. Date palm growers can cure the Hillawi date fruit by adopting sun drying
techniques such as SDT4 (DSE with removal in baskets and covered during night)
with good fruit quality composition and can get maximum return.
4.5 Future research needed
Ethephon application should be applied on various other commercially grown date palm
cultivars to avoid the synchronization of monsoon rains as well as improving the fruit
ripening and quality. More research work is needed to investigate the response of
ethephon at genetic and molecular level to dissect the biochemistry and physiology of
ethylene production from pre-harvest application of ethephon. There is a need to measure
the detrimental effects of various fruit ripening agents. To explore the complete
nutritional profile of date fruit at various maturity stages with respect to ethylene
synthesis and carbon dioxide production. There is a need to create awareness among the
date palm growers about the quality processing of soft and/or semi dried dates by
replacing the fully dried date’s technology (Chohara formation) with higher economic
return and more nutritional value. For this purpose Government and Private sector should
be involved at national level to boost up the dates processing industry and post-harvest
handling.
188
LITERATURE CITED
A.O.A.C. 1980. Official Methods of Analysis. Association of Analytical Chemists.
Arlington, USA.
Abdelhak, M., E. Guendez, K. Eugene and P. Kefalas. 2005. Phenolic profile and
antioxidant activity of the Algerian ripe date palm fruit (Phoenix dactylifera).
Food Chem., 89: 411-420.
Abdel-Hamid, N. 2000. Effect of time, rate and patterns of thinning, leaf bunch ratio and
male type on “Zaghloul” date yield and quality. Arab. J. Agric. Sci., 8: 305-
317.
Abdel-Latif, S.A. 1988. The physiology of ripening of date palm fruit (Phoenix
dactylifera L.). M.Sc. Diss., Univ. Baghdad, Iraq.
Abdul, A. and A. Allaith. 2008. Antioxidant activity of Bahraini date palm (Phoenix
dactylifera L.) fruit of various cultivars. Int. J. Food Sci. Technol., 43: 1033-
1040.
Abeles, F.B., P.W. Morgan and M.E. Saltveit. 1992. Ethylene in plant biology, vol. 15,
2nd ed. Academic Press, San Diego, California.
Ahmed, A., A.W. Ahmed and R.K. Robinson. 1995. Chemical composition of date
varieties as influenced by the stage of ripening. Food Chem., 54: 305-309.
Aina, J.O. 1990. Physico-chemical changes in African Mango (Irvingia gabonensis)
during normal storage ripening. Food Chem., 36: 205-12.
Ainsworth, A.A. and K.M. Gillespie. 2007. Estimation of total phenolic content and other
oxidation substrates in plant tissues using Folin-Ciocalteu reagent. Nature, 4:
875-877.
Akl, A.M., M.A. Ragab and A.Y. Mohamed. 2004. Yield and fruit quality of Sewy date
palms in response to some fruit thinning treatments. Second International
Conference on Date Palm. El-Arish, Egypt, 6-8 Oct.
Al Farsi, M.A. and C.Y. Lee. 2008. Nutritional and functional properties of dates: a
review. Critical Rev. Food Sci. Nutr., 48: 877-887.
Al-Darwish, Z.S.B.A. 2010. Effect of the fruit thinning on the date palm fruit shrivels of
the Ghar cultivar. Fourth International Conference on Date Palm. Abu Dhabi,
U.A.E., 15-17 March. P. 63.
Alexander, L. and D. Grierson. 2002. Ethylene biosynthesis and action in tomato: a model
for climacteric fruit ripening. J. Exp. Bot., 53: 2039-2055.
189
Al-Farsi, M., C. Alasalavar, A. Morris, M. Baron and F. Shahid, 2005a. Compositional
and sensory characteristics of three native sun-dried date (Phoenix dactylifera
L.) varieties grown in Oman. J. Agric. Food Chem., 53: 7586-7591.
Al-Farsi, M., C. Alasalvar, A. Morris, M. Baron and F. Shahidi. 2005b. Comparison of
antioxidant activity, anthocyanins, carotenoids, and phenolics of three native
fresh and sun-dried date (Phoenix dactylifera L.) varieties grown in Oman. J.
Agric. Food Chem., 53: 7592-7599.
Al-Farsi, M., C. Alasalvar, M. Al-Abid, K. Al-Shoaily, M. Al-Amry and F. Al-Rawahy.
2007. Compositional and functional characteristics of dates, syrups, and their
by-products. Food Chem.. 104: 943-947.
Al-Ghamdi, A.S., O.A. Al-Tahir and A.A. Al-Khateeb. 1993. Thinning stage effects on
fruit size, yield and fruit quality of date palm (Phoenix dactylifera L.) Cv.
Khalas. Third Symposium on date palm, Saudi Arabia, Book of Abstracts, P:
88.
Al-Hooti, S., J.S. Sidhu and H. Qabazard. 1995. Studies on the physico-chemical
characteristics of date fruits of five U.A.E. cultivars at different stages of
maturity. Arab Gulf J. Sci. Res., 13: 553-569.
Al-Hooti, S., J.S. Sidhu and H. Qabazard. 1997. Physicochemical characteristics of five
date fruit cultivars grown in the United Arab Emirates. Plant Food Hum. Nutr.,
50: 101-113.
Al-Hooti, S.N., J.S. Sidhu, J.M. Al-Saqer and A. Al-Othman. 2002. Chemical
composition and quality of date syrup as affected by pectinase/cellulase
enzyme treatment. Food Chem., 79: 215-220.
Ali-Dinar, H.M., A.A. Alkhateeb, I. Al. Abdulhadi, A. Alkhateeb, K.A. Abugulia and
G.R. Abdulla. 2002. Bunch thinning improves yield and fruit quality of date
palm (Phoenix dactylifera L.). Egypt. J. Appl. Sci., 17(11): 228-238.
Ali-Mohamed, A.Y. and A.S.H. Khamis. 2004. Mineral ion content of the seeds of six
cultivars of Bahraini date palm (Phoenix dactylifera L.). J. Agric. Food Chem.,
52: 6522-6525.
Al-Jasim, H.A. and K.S. Al-Delaimy. 1972. Pectinesterase activity of some Iraqi dates at
different stages of maturity. J. Sci. Food Agric., 23: 915-917.
Al-Kahtani, H.A., H.M. Abu-Tarboush, Y.N. Al-Dryhim, M.A. Ahmed, A.S. Bajaber,
E.E. Adam, and M.A. El-Mojaddidi. 1998. Irradiation of dates: insect
190
disinfestation, microbial and chemical assessments, and use of
thermoluminescence technique. Radiat. Phys. Chem., 53: 181-187.
Al-Khateeb, A.A. and H.M. Ali-Dinar. 2002. Date Palm in Kingdom of Saudi Arabia:
Cultivation, Production and Processing. Translation, authorship and publishing
Centre, King Faisal University, Kingdom of Saudi Arabia. P. 188.
Allaith, A.A.A. 2008. Antioxidant activity of Bahraini date palm (Phoenix dactylifera L.)
fruit of various cultivars. Int. J. Food Sci. Technol., 43: 1033-1040.
Al-Mughrabi, M.A., M.A. Bacha and A.O. Abdelrahman. 1989. Influence of pre-harvest
application of ethrel and 2, 4-D on fruit quality. J. King Saud Univ. Agri. Sci.,
1: 95-102.
Al-Noimi, J. and G. Al-Amir. 1980. Physiology and morphology of date palm. Al-Basra
University, Iraq: Faculty of Agriculture.
Al-Obeed, R.S., M.A. Harhash and N.S. Fayez. 2005. Effect of bunch thinning on yield
and fruit quality of Succary date palm cultivar grown in the Riyadh region. J.
King Saud Univ. Agri. Sci., 2: 235-249.
Al-Qarawi, A.A., B.H. Ali, S.A. Al-Mougy and H.M. Mousa. 2003. Gastrointestinal
transit in mice treated with various extracts of date (Phoenix dactylifera L.). J.
Food Chem. Toxicol., 41: 37-39.
Al-Qarawi, A.A., H. Abdel-Rahman, B.H. Ali, H.M. Mousa and S.A. El-Mougy. 2005.
The ameliorative effect of dates (Phoenix dactylifera L.) on ethanol-induced
gastric ulcer in rats. J. Ethno-pharmacology, 98: 313-317.
Al-Qarni, S.S.M. 2005. Biochemical changes during date palm fruits ripening. MSc.
Thesis of science in biochemistry. Faculty of science. King Saud University.
Riyadh, Saudi Arabia, P. 147.
Al-Rawahi, A.S., S. Kasapis and I.M. Al-Bulushi. 2005. Development of a date
confectionary: Part 1. Relating formulation to instrumental texture. Intr. J. Food
Prop., 8: 457-468.
Al-Shahib, W. and R.J. Marshall. 2003. The fruit of the date palm: its possible use as the
best food for the future? Int. J. Food Sci. Nutr., 54: 247-259.
Al-Wasfy, M.M. and R.A.A. Mostafa, 2008. Effect of different methods of fruit thinning
on Zaghloul date palm production and fruit quality. Assiut. J. Agric. Sci., 39:
97-106.
Amira, E.A., E.B. Saafi, B. Mechri, L. Lahouar, M. Issaoui, M. Hammami and L. Achour.
2012. Effects of the ripening stage on phenolic profile, phytochemical
191
composition and antioxidant activity of date palm fruit. J. Agric. Food Chem.,
60: 10896-10902.
Amoros, A., M.T. Pretel, M.S. Almansa, M.A. Botella, P.J. Zapata and M. Serrano. 2009.
Antioxidant and nutritional properties of date fruit from Elche Grove as
affected by maturation and phenotypic variability of date palm. Food Sci.
Technol. Int., 15: 65-72.
Anderson, J.L. 1968. New chemical may aid mechanical harvesting of sour cherries. Utah
Sci., 29: 111-113.
Armitage, A.M. 1989. Promotion of fruit ripening of ornamental peppers by ethephon.
HortScience, 24: 962-964.
Arora, J.S., R.N. Pal and J.S. Jawanda. 1973. Effect of ethrel on degreening of Valencia
sweet orange (C. sinensis Osbeck). Punjab Hort. J., 13: 13-17.
ASF. 2010. Date palm Protection Project Report. Lahore, Pakistan.
Asif, M. 2012. Physico-chemical properties and toxic effect of fruit-ripening agent
calcium carbide. Ann. Trop. Med. Public, 5: 150-156.
Asif, M.I. and O.A. Al Taher. 1983. Ripening of Khasab dates by sodium chloride and
acetic acid. Date Palm J., 2: 121-128.
Awad, M.A. 2007. Increasing the rate of ripening of date palm fruit (Phoenix dactylifera
L.) cv. Helali by preharvest and post-harvest treatments. Post-harvest Biol.
Technol. 43: 121-127.
Awad, M.A. and A. de Jager. 2002. Formation of flavonoids, especially anthocyanin and
chlorogenic acid in „Jonagold‟ apple skin: influences of growth regulators and
fruit maturity. Sci. Hort., 93: 257-266.
Awad, M.A., A.D. Al-Qurashia and S.A. Mohamed. 2011. Antioxidant capacity,
antioxidant compounds and antioxidant enzyme activities in five date cultivars
during development and ripening. Sci. Hort., 129: 688-693.
Bacha, M.A., T.A. Nasr and M.A. Shaheen. 1987. Changes in Physical and Chemical
Characteristics of the Fruits of Four Date Palm Cultivars. Proc. Saudi Biol.
Soc., 10: 285-295.
Bal, J.S., G.S. Bajwa and S.N. Singh. 1996. Role of ethephon in inducing early ripening
and marketing of ber (Zizyphus mauritiana Lamk). Indian J. Hort., 53: 38-41.
Bal, J.S., P.S. Kahlon, J.S. Jawanda and S.S. Sandhu. 1992. Effect of pre-harvest spray on
growth regulators at turning stage on the maturity of ber fruits (Ziziphus
mauritiana Lamk.). Acta Hort., 321: 318-325.
192
Baliga, M.S., B.R.V. Baliga, S.M. Kandathil, H.P. Bhat and P.K. Vayalil. 2011. A review
of the chemistry and pharmacology of the date fruits (Phoenix dactylifera L.).
Food Res. Int., 44: 1812-1822.
Baloch, M.K., S.A. Saleem, K. Ahmad, A.K. Baloch and W.A. Baloch. 2006. Impact of
controlled atmosphere on the stability of Dhakki dates. Swiss Soci. Food Sci.
Technol., 39: 671-676.
Ban, T., M. Kugishima, T. Ogata, S. Shiozaki, S. Horiuchi and H. Ueda. 2007. Effect of
ethephon (2-chloroethylphosphonic acid) on the fruit ripening characters of
rabbit eye blueberry. Sci. Hort., 112: 278-281.
Barreveld, W.H. 1993. Date palm Products. Food and Agriculture Organization of the
United Nations, Agricultural Services Bulletin no.101, Food and Agriculture
Organization of the United Nations, Rome, Italy.
Barrow, S. 1998. A monograph of Phoenix dactylifera L. Kew Bul., 53: 513-575.
Bassal, M.A. and M.D. El-Deeb. 2002. Effect of thinning and some growth regulators on
yield and fruit quality of Zaghloul date palm. Zagazig J. Agric. Res., 29: 1815-
1837.
Batal, K.M. and D.M. Granberry. 1982. Effects of growth regulators on ripening and
abscission of pimiento and paprika peppers. Hort. Sci., 17: 944-946.
Bauza, E. 2002. Date palm kernel extract exhibits antiaging properties and significantly
reduces skin wrinkles. Int. J. Tissue Reac., 24: 131-136.
Beaudry, R.M. and S.J. Kays. 1988. Effect of ethylene source on abscission of pepper
plant organs. Hort. Sci., 23: 742-744.
Behseresht, R., R. Khademi and P. Bayat. 2007. The effect of bunch thinning methods on
quality and quantity of date palm cv. Kabakab. Fourth Symposium on Date
palm. Al-Hassa, Saudi Arabia, 5-8 May.
Belarbi, A., C. Aymard, J.M. Meot, A. Themelin and M. Reynes. 2000. Water desorption
isotherms for eleven varieties of dates. J. Food Eng., 43: 103-107.
Ben-yehoshua, S., S. Iwahori and J.M. Lyons. 1970. Role of ethylene and ethrel in the
development of fig fruit. Israel J. Agric. Res., 22: 173-177.
Besbes, S., C. Blecker, C. Deroanne, N.E. Drira and H. Attia. 2004. Date seeds: chemical
composition and characteristic profiles of the lipid fraction. Food Chem., 84:
577-584.
Bhowmik, S.R. and J.C. Pan. 1992. Shelf life of mature green tomatoes stored in
controlled atmosphere and high humidity. J. Food Sci., 57: 948-953.
193
Biglari, F. 2009. Assessment of antioxidant potential of date (Phoenix dactylifera L.)
fruits from Iran, effect of cold storage and addition to minced chicken meat;
MSc. Thesis. School of Industrial Technology. University of Sains Penang,
Malaysia, P. 15-105.
Biglari, F., A.F.M. AlKarkhi and A.M. Easa. 2008. Antioxidant activity and phenolic
content of various date palm (Phoenix dactylifera L.) fruits from Iran. Food
Chem., 107: 1636-1641.
Blanke, M.M. and A. Leyhe. 1987. Stomatal activity of the grape berry cv. „Riesling‟,
„Muller-Thurgau‟ and „Ehrenfelser‟. J. Plant Physiol., 127: 451-460.
Bonora, E., D. Stefanelli and G. Costa. 2013. Nectarine Fruit Ripening and Quality
Assessed Using the Index of Absorbance Difference (𝐼AD). Int. J. Agron., 1-9.
Booij, I., G. Piombo, J.M. Risterucci, M. Coupe, D. Thomas and M. Ferry. 1992. Study
on the chemical composition of dates at different stages of maturity for the
varietial characterization of various cultivars of date palm (Phoenix dactylifera
L.). Fruits, 47: 667-678.
Brady, C.J. 1987. Fruit ripening. Annual Rev. Plant Physiol., 38: 155-178.
Brar, J.S., H.S. Dhaliwal and J.S. Bal. 2012. Influence of paclobutrazol and ethephon on
fruit quality of „Allahabad Safeda‟ Guava. HortFlora Res. Spec., 1: 135-138.
Brown, S.C., and B.G. Coombe. 1985. Solute accumulation by grape pericarp cells. III.
Sugar changes in vivo and the effect of shading. Biochem. Physiol., 180: 371-
381.
Bubola, M., Ð. Peršurić and K. Ganić. 2011. Impact of cluster thinning on productive
characteristics and wine phenolic composition of cv. Merlot. J. Food Agric.
Environ., 9: 36-39.
Carillo, L.A., F. Ramirez-Bustamante, F.B. V. Torres, R. Rojas- Villegas and E.M. Yahia
2000. Ripening and quality changes in mango fruits as affected by coating with
an edible film. J. Food Quality, 23: 479-86.
Çelikel, F.G., K. Kaynas, S. Özelkök, and U.U.M.L Ertan. 1997. Effects of ethephon on
fruit development and ripening of the fig (Ficus carica L.) variety "bursa
siyahi". Acta Hort., 441: 145-152.
Chaira, N., M.I. Smaali, M. Martinez-Tomé, A. Mrabet, M.A. Murcia, and A. Ferchichi.
2009. Simple phenolic composition, flavonoid contents and antioxidant
capacities in water–methanol extracts of Tunisian common date cultivars
(Phoenix dactylifera L.). Int. J. Food Sci. Nutr., 60: 316-329.
194
Chakraverty, A., A.S. Mujumdar, G.S.V. Raghavan and H.S. Ramaswamy. 2003.
Handbook of Postharvest Technology. Marcel Dekker, New York.
Chao, C.T. and R.R. Krueger. 2007. The Date palm (Phoenix dactylifera L.): Overview of
biology, uses, and cultivation. Hort. Sci., 42: 1077-1082.
Chatha, G.A., A.H. Gillani and B. Ahmad. 1985. Effect of curing agents on the chemical
composition and keeping quality of date fruit. J. Agric. Res., 23: 71-77.
Chauhan, K.S. and C. Parmar. 1981. Degreening of Mosambi with ethrel. Third
International Symposium. Subtropical and Tropical Horticulture, Bangalore,
India, 8-14 Feb. Hort. Soc. India, P. 153-156.
Chauhan, K.S. and R.S. Rana. 1974. Effect of ethrel on degreening of Washington navel
orange. Indian J. Hort., 31: 154-156.
Cheng, T.S., J.D. Floros, R.L. Shewfelft and C.J. Chang. 1988. The effect of high
temperature-stress on ripening of tomatoes (Lycopersicon esculentum L.). J.
Plant Physiol., 132: 459-464.
Conrad, R.S. and F.J. Sundstrom. 1987. Calcium and ethephon effects on Tabasco pepper
leaf and fruit retention and fruit color development. J. Am. Soc. Hort. Sci., 112:
424-426.
Cooke, A.R. and D.I. Randall. 1968. 2-chloroethylphosphonic acids as ethylene releasing
agents for the induction of flowering in pineapples. Nature, 218: 974-975.
Coombe, B.G. 1973. The regulation of set and development of the grape berry. Acta Hort.
34: 261-274.
Costa, G. and G. Vizzotto. 2000. “Fruit thinning of peach trees,” Plant Growth Reg., 31:
113-119.
Couey, H.M. 1989. Heat treatment for control of postharvest diseases and insect pests of
fruits. Hort. Sci., 24: 198-202.
Crippen, D.D., and J.C. Morrison. 1986. The effects of sun exposure on the compositional
development of „Cabernet Sauvignon‟ berries. Amer. J. Enol. Viticul., 37: 235-
242.
Cua, A.U. and M.C. Lizada. 1990. Ethylene production in the 'Carabao' mango
(Mangifera indica L.) fruit during maturation and ripening. Acta Hort., 269:
169-179.
Curry, E.A. 1994. Pre-harvest applications of ethephon reduce superficial scald of „Fuji‟
and „Granny‟ apples in storage. J. Hort. Sci., 69: 1111-1116.
195
Davoodian, A. 1999. Effects of leaf area and growth regulators on fruit drop of
Mordasang date cultivar. Final Report of Research Design. Date Palm &
Tropical Fruits Research Institute of Iran, Ahwaz, Iran.
Dawson,W.H.W. 1982. Production and Preservation of date; Translated by R.
Sanadgol.Agricultural Promotion Organization Publication: Tehran, Iran, P.
326.
Delgado, R.., J.I. Gallegos, P. Martín and M.R. González. 2004. Influence of ABA and
ethephon treatments on fruit composition of „Trempranillo‟ grapevines. Acta
Hort., 640: 321-326.
Di-Marco, L., T. Caruso, F.P. Marra and A. Motisi, 1992. Research on flower thinning of
early-ripening peach and nectarine with urea. Fruit Var. J. 186-190.
Djerbi, M. 1996. Date palm Production (In French). Rome Italy; FAO, Agricultural
Services Bulletin.
Dokoozlian, N.K, D.A. Luvisi, P.L. Schrader and M.M. Moriyama. 1994. Influence of
trunk girdle timing and ethephon on the quality of Crimson Seedless table
grapes. In: Proc. Int. Symp. Table Grape Production. Am. Soc. Enol. Vitic.
(Eds.) Rantza, J.M. & Lewis, K.B., June, Anaheim, California, USA. P. 237-
240.
Dokoozlian, N.K. and W.M. Kliewer. 1996. Influence of light on grape berry growth and
composition varies during fruit development. J. Amer. Soc. Hort. Sci., 121:
869-874.
Doymaz, I. 2004. Convective air-drying characteristics of thin layer carrots. J. Food Eng.,
61: 359-364.
Doymaz, I. 2005. Drying characteristics and kinetics of okra. J. Food Eng., 69: 275-279.
Drake, S.R., D.C. Elfving and M.A. Drake. 2006. Effects of Aminoethoxyvinylglycine,
ethephon and 1-methylcyclopropene on apple fruit quality at harvest and after
storage. Hort. Technol., 16: 16-23.
Duke, J.A. 1992. Handbook of phytochemicals of GRAS herbs and other economic
plants. Boca Raton, FL, USA: CRC Press.
Ed Peter, K.V. 2009. Basics of Horticulture. New India Publishing Agency. Pitam Pura,
New Delhi India.
Edgerton, L.J. and G.D. Blanpied. 1970. Interaction of succinic acid 2, 2-dimethyl
hydrazide, 2chloroethylphosphonic acid and auxins on maturity, quality and
abscission of apples. J. Am. Soc. Hort. Sci., 95: 664-68.
196
El Arem, A., G. Flamini, E.B. Saafi, M. Issaoui, A. Ferchichi, M. Hammami and L.
Achour. 2011. Chemical and aroma volatile compositions of date palm
(Phoenix dactylifera L.) fruit at three edible maturation stages. Food Chem.,
127: 1744-1754.
El Hadrami, A., F. Daayf and I. El Hadrami. 2011. Date Palm Genetics and Breeding. pp.
479-502. In: Jain, S.M., J.M. Al-Khayri and D.V. Johnson (Eds.) Date Palm
Biotechnology, Springer, Netherlands.
El Hadrami, I. and A. El Hadrami. 2009. Breeding date palm. In: S. M. Jain and P. M.
Priyadarshan, (Eds.). pp. 191-216. Breeding Plantation Tree Crops. Springer,
New York.
El-Agamy, S.Z., T.K. El-Mahdy and O.A.A. Khalil. 2001. comparative study of the
performance of soft type date grown in arid environment. Second International
Conference on Date Palm, Al-Ain, U.A.E. March 25-27, P. 686-710.
El-Assar, A.M. 2005. Response of "Zaghloul" date yield and fruit characteristics to
various organic and inorganic fertilization types as well as fruit thinning
models in a rich carbonate soil. J. Agric. Sci., 30: 2795-2814.
El-Assi, N.M. 2004. Alleviating chilling injury and maintaining quality of tomato fruit by
hot water treatment. Emir. J. Agric. Sci., 16: 01-07.
El-Kereamy, A., C. Chervin, J. Raynal, M. Afifi and J.P. Roustan. 2000. Ethylene and
ethanol sprayed at véraison enhances the production of anthocyanins in,
„Cabernet Sauvignon‟ grapes. Abstr. 138 6th International Symposium on
Grapevine Physiology and Biotechnology. Heraklion, Greece 11-16 June.
Elleuch, M., S. Besbes, O. Roiseux, C. Blecker, C. Deroanne, N.E. Drira and H. Attia,
2008. Date flesh: Chemical composition and characteristics of dietary fibre.
Food Chem., 111: 676-682.
El-Shibli, S. and H. Korelainen. 2009. Biodiversity of date palm (Phoenix dactylifera L.)
in Sudan: Chemical, morphological and DNA polymorphism of selected
cultivars. Plant Genet. Resour., 7: 194-203.
Eltayeb, E.A., A.S. Al-Hasni and S.A. Farooq. 1999. Changes in soluble sugar content
during the development of fruits in some varieties of Omani date palm
(Phoenix dactylifera L.). Pak. J. Biol. Sci., 2: 255-258.
Ensminger, A.H. M.E. Ensminger, J.E. Konlande and J.R.K. Robson. 1995. The Concise
Encyclopedia of Foods and Nutrition; CRC Press LLC: Florida, USA, p.247.
197
Erskine, W., A.T. Moustafa, A.E. Osman, Z. Lashine, A. Nejatian, T. Badawi and S.M.
Ragy. 2004. Date Palmin the GCC countries of the Arabian Peninsula.
International Centre for Agricultural Research in the Dry Areas (ICARDA).
Fadel, M.A., L. Kurmestegy, M. Rashed and Z. Rashed. 2006. Fruit color properties of
different cultivars of dates (Phoenix dactylifera L.).Agricultural Engineering
International: the CIGR E journal, VIII (Manuscript FP 05 005).
Falade, K.O. and E.S. Abbo. 2007. Air-drying and rehydration characteristics of date
palm (Phoenix dactylifera L.) fruits. J. Food Eng., 79: 724-730.
Fallahi, M. 1996. Growth, Treatment, and Packaging of Date; Barsava Publication:
Tehran, Iran, P. 124.
Fallik, E., S. Grinberg, S. Alkalai, O. Oded Yekutieli, A. Wiseblum, R. Regev, H. Beres
and E Bar-Lev. 1999. A unique rapid hot water treatment to improve storage
quality of sweet pepper. Postharvest Biol. Technol., 15: 25-32.
FAOSTAT, 2011. Production Year Book. http:// Faostat.Fao.org/ site/ 339/deaflt.aspx.
Farag, K.M. 1989. Enhancing ethephon effectiveness by modifying cuticular transport or
stimulating ethylene production in cranberry fi-uit. Ph. D. Thesis. University of
Wisconsin-Madison. P. 216.
Farag, K.M., P. Jiwan and P. Palta. 1992. Ursolic acid, ascorbic acid or urea together with
ethephon accelerate anthocyanin production in cranberry fruit. J. Plant Growth
Regul., 20: 29-33.
Farahnaky, A. and H. Afshari-Jouybari. 2001. Physicochemical changes in Mazafati date
fruits incubated in hot acetic acid for accelerated ripening to prevent diseases
and decay. Sci. Hort., 127: 313-317.
Farahnaky, A., H. Askari, M. Bakhtiyari and M. Majzoobi. 2009. Accelerated ripening of
Kabkab dates using sodium chloride and acetic acid solutions. Iran Agric. Res.,
27: 99-111.
Fayadh, J.M. and S.S. Al-Showiman. 1990. Chemical composition of date palm (Phoenix
dactylifera L.). J. Chem. Soc. Pak., 12: 84-103.
Frenkel, C. and T.G. Hartman. 2012. Decrease in fruit moisture content heralds and might
launch the onset of ripening processes. J. Food Sci., 77: 365-376.
Fuch, Y. and A. Cohen. 1969. De-greening of citrus fruit with ethrel. J. Am. Soc. Hort.
Sci., 94: 617-618.
Gala, M.S.; A.A.A. El-Aziz and A.R. El-Tawil. 2001. Using ethrel for banana ripening.
Egyptian J. Agric. Res., 79: 271-295.
198
Gamage, T.V. and M.S. Rehman.. 1999. Post-harvest handling of foods of plant origin.
In: Rehman, M.S. (Ed.) Handbook of Food Preservation. Marcel Dekker Inc.,
New York. P. 11-46.
Garcia-Jimenez, J., J. Busto, A. Vicent, and J. Armengol. 2004. Control of Dematophora
necatrix on Cyperus esculentus tubers by hot-water treatment. Crop Protect.,
23: 619-623.
Gasim, A.A.A. 1994. Changes in sugar quality and mineral elements during fruit
development in five date palm cultivars in Al-Madinah Al-Munawwarah.
JKAU: Sci., 6: 29-36.
Gautier, H., V. Diakou-Verdin, C. Benard, M. Reich, M. Buret, F. Bourgaud, J.L.
Poessel, C. Caris-Veyrat and M. Genard. 2008. How does tomato quality
(sugar, acid, and nutritional quality) vary with ripening stage, temperature, and
irradiance? J. Agric. Food Chem., 56: 1241-1250.
Godara, R.K., N.R. Godara and N.S. Nehra. 1990. Effect of level of thinning on ripening
of date palm fruit (Phoenix dactylifera L.) cv. Shamran. Res. Dev. Rep., 7: 21-
25.
Goffinet, M.C., T.L. Robinson and A.N. Lakso. 1995. A comparison of „Empire‟ apple
fruit size and anatomy in un-thinned and hand thinned trees. J. Hort. Sci., 70:
375-387.
Goldschmidt, E.E., M. Huberman, and R. Goren, 1993. Probing the roles of endogenous
ethylene in the degreening of citrus fruit with ethylene antagonists. J. Plant
Growth Regul., 12: 325-329.
GOP (Government of Pakistan), 2011. Fruit, Vegetable and Condiments. Statistics of
Pakistan. Ministry of Food, Agriculture and Livestock (Economic Wing),
Islamabad.
Gray, J., S. Pictor, J. Shabbeer, W. Schuch and D. Grierson 1992. Molecular biology of
fruit ripening and its manipulation with antisense genes. Plant Mol. Biol., 19:
69-87.
Grierson, D., G.A. Tucker and N.G. Robertson. 1981. The molecular biology of ripening.
In: Friend, J., and Rhodes, M.J.C., (Eds.). Recent Advances in the
Biochemistry of Fruits and Vegetables. Academic Press, London. 149-160 pp.
Guine, R.P.F. and J.A.A.M. Castro. 2002. Pear drying process analysis: Drying rates and
evaluation of water and sugar concentrations in space. Dry. Tech., 20: 1515-
1526.
199
Hammam, M.S., A. Sabour and E. Sanaa. 2002. Effect of some fruit thinning treatments
on yield and fruit quality of Zaghloul date palm. J. Agric. Sci., 10: 261-271.
Hammett, L.K. 1976. Ethephon influence on storage quality of „Starkrimson Delicious‟
and „Golden Delicious‟ apples. Hort. Sci., 11: 57-59.
Hamshiri, M.H. and M. Rahemi. 1999. Effect of ethphon, sodium chloride and acetic acid
on quality of Mazafati date fruits. Iranian J. of Agri. Sci. 29 (4): 777-785.
Han, D.H., S.M. Lee, C.H. Lee and S.B. Kim. 1996. Effects of ABA and ethephon
treatments on coloration and fruit quality in Kyoho grape. J. Kor. Soc. Hort.
Sci., 37: 416-420.
Haq, Z. 1990. Effect of NaCl and acetic acid on physio-chemical character and storage of
date fruit (Phoenix dactylifera L.) cv. Dhakki under the normal conditions.
M.Sc. Thesis. Uni. Agri., Faisalabad.
Harman, J.E. and K.J. Patterson. 1984. Kiwi fruit, tamarillos and feijoas maturity and
storage effect on keeping and eating quality. Agric. Link.
Hartmann, C. 1992. Biochemical changes in harvested cherries. Postharvest Biol.
Technol., 1: 231-240.
Hasegawa, S. And D.C. Smolensky. 1971. Cellulase in dates and its role in fruit
softening. J. Food Sci., 36: 966-967.
Hasegawa, S. and V.P. Maier. 1980. Polygalacturonase content of dates and its relation to
maturity and softness. J. Food Sci., 34: 527-529.
Hashempoor, M. 1999. Date Treasure; Agricultural Education Publication: Tehran, Iran,
P. 668.
Hashinaga, F. and S. Itoo. 1985. Effect of ethephon on the maturity of Meiwa Kumquat
fruit. Bulletin Faculty of Agriculture Kagoshime University. 35: 43-47.
Hole, C.C. and P.A. Scott. 1981. The effect of fruit shading on yield in Pisum sativum L.
Ann. Bot., 48: 827-835.
Hong, M.N., B.C. Lee, S. Mendonca, M.V.E. Grossmann and R. Verhe. 1999. Effect of
infiltrated calcium on ripening of tomato fruits. LWT. J. Food Sci., 33: 2-8.
Hong, Y.J., F.A. Tomas-Barberan, A.A. Kader and A.E. Mitchell. 2006. The flavonoids
glycosides and procyanidin composition of Deglet Noor dates (Phoenix
dactylifera L.). J. Agric. Food Chem., 54: 2405-2411.
Hortwitz, W. 1960. Official and tentative method of analysis. Association of Official
Agriculture Chemists, Washington, D.C., 9: 314-320.
200
Hoyer, L. 1996. Critical ethylene exposure for Capsicum annuum “janne” is dependent on
an interaction between concentration, duration and developmental stage. J.
Hort. Sci., 71: 621-628.
Hui, Y.H. 2006. Fruit and Fruit Processing; Blackwell Publishing: Ames, Iowa. P. 391-
411.
Hulme, A.C. 1970. The biochemistry of fruits and their products, Vol. 1, London and
New York: Academic Press.
Hussein, M.A., Z. Samir, EI-Agamy, A.K. Amin and S. Gala. 1993. Physiological studies
for extending harvesting season of Samany dates under Assiut conditions. B.
Effect of ethephon and fruit thinning. Third Symposium on date palm in Saudia
Arabia. P. 106.
Ibrahim, A.M. and M.N.H. Khalif. 1998. The date palm: Its Cultivation, Care and
Production in the Arab World. Almaarif Public Company, Alexandria, Egypt.
Iizadi, M., M.P. Shirazi, A.D. Avoodian and B. Damankeshan, 2010. Effect of bunch
thinning methods on date bunch fading disorder at pollination and kimri stages.
Fourth International Date Palm Conference, Abu Dhabi, U.A.E. 15-17 March.
P. 57.
Inaba, M. and K. Chachin. 1988. Influence of and recovery from high-temperature stress
on harvested mature green tomatoes. Hort. Sci., 23: 190-192.
Ishurd, O. and J.F. Kennedy. 2005. The anti-cancer activity of polysaccharide prepared
from Libyan dates (Phoenix dactylifera L). Carbohydr. Polym., 59: 531-535.
Itamura, H., T. Kitamura, Taira, H. Harada, N. Ito, Y. Takahashi and T. Fujushima. 1991.
Relationship between fruit softening, ethylene production and respiration in
Japanese persimmon “Hiratanenashi”. J. Japanese Soc. Hort. Sci., 60: 695-701.
Jabbar, A., A.U. Malik, M. Saeed, O.H. Malik, M. Amin, A.S. Khan, I.A. Rajwana, B.A.
Saleem, R. Hameed and M.S. Mazhar. 2011. Performance of hot water
phytosanitary treated mangoes for intended export from Pakistan to Iran and
China. Int. J. Agric. Biol., 13: 645-651.
Jacobi, K., E. MacRae and S. Hetherington. 2001. Postharvest heat disinfestations
treatments of mango fruit (Review). Sci. Hort. Cult., 89: 171-193.
Jacobi, K.K., L.S. Wong and J.E. Giles. 1995. Effect of fruit maturity on quality and
physiology of high humidity hot air treated „Kensington‟ mango (Mangifera
indica Linn.). Post-harvest Biol. Technol., 5: 149-59.
201
Jamil, M.S., R. Nadeem, M.A. Hanif, M.A. Ali and K. Akhtar. 2010. Proximate
composition and mineral profile of eight different unstudied date (Phoenix
dactylifera L.) varieties from Pakistan. Afr. J. Biotechnol., 9: 3252-3259.
Johnson, T.L. and C.W. Nagel. 1976. Composition of Central Washington grapes during
maturation. Am. J. Enol. Viticul., 27: 15-20.
Jones, K. M. 1979. The use of ethephon in advancing red colour in the apple cultivar
'Tydeman Early'. Aust. J. Exp. Agri. Animal Husb., 19: 251-256.
Kader, A.A. 1986. Effects of postharvest handling procedures on tomato quality. Acta
Hort., 190: 209-221.
Kader, A.A. and A. Hussein. 2009. Harvesting and post-harvest handling of dates.
ICARDA, Aleppo, Syria. P. 15.
Kahn, B.A., J.E. Motes and N.O. Maness. 1997. Use of ethephon as a controlled
abscission agent on paprika pepper. Hort. Sci., 32: 251-255.
Kalra, S.K., J.S. Jawanda and S.K. Munshi. 1977. Studies on softening of Doka dates by
sodium chloride and acetic acid. Ind. J. Hort., 34: 220-224.
Kamal, H.M. 1995. Effect of some growth regulators on the physical and chemical
properties of date fruits. AGRIS Bull., 46: 215-228.
Kappel, F. and G.H. Neilsen. 1994. Relationship between light microclimate, fruit
growth, fruit quality, specific leaf weight and N and P content of spur leaves of
„Bartlett‟ and „Anjou‟ pear. HortScience, 59: 187-196.
Kato, K. 1990. Astringency removal and ripening in persimmons treated with ethanol and
ethylene. HortScience, 25: 205-207.
Kenoyer, J. Mark and K. Heuston. 2005. The Ancient South Asian World. Oxford
University Press. 176 pages. ISBN 0-19-517422-4.
Ketsa, S., S. Childtragool, J.D. Klein and S. Lurie. 1998. Ethylene synthesis in mango
fruit following heat treatment. Postharvest Biol. Technol., 15: 65-72.
Ketsa, S., S. Childtragool, J.D. Klein and S. Lurie. 1999. Ethylene synthesis in mango
fruit following heat treatment. Postharvest Biol. Technol., 15: 65-72.
Khademi, R. 1998. Effects of different methods of fruit thinning on fruit ripening,
quantity and quality of Kabkaab dates. Final Report of Research Design.
Agricultural Research Center of Boushehr, Boushehr, Iran.
Khalifa, A.S., A.I. El-Kady, K.M. Abdalla and A.M. El-Hamdy. 1987. Influence of
thinning patterns and leaf/bunch ratio on “Zaghloul” dates. Ann. Agric. Sci.,
32: 637-647.
202
Khalifa, A.S., M. Abdel-Azeem, EI-Hammady, M. Mostafa, EI-Hammady and A. Yussuf.
1975. Ripening of date fruits as affected by ethephon. Egypt. J. Hort., 2: 83-
102.
Khare, C.P. 2007. Indian medicinal plants: An illustrated dictionary. Springer Reference.
Khatchadourian, H.A., W.N. Sawaya, J.K. Khalil, W.J. Safi and A.A. Mashadi. 1982.
Utilization of dates, (Phoenix dactylifera L.), grown in the Kingdom of Saudi
Arabia, in various date products. First International Symposium on date palm.
King Faisal University, Saudi Arabia, March, 23-25.
Kim, D.O., S.W. Jeong and C.Y. Lee. 2003. Antioxidant capacity of phenolic
phytochemicals from various cultivars of plums. Food Chem., 81: 321-326.
Kim, H.C. 2010. Effect of Ethephon on Fruit Enlargement and Coloring of 'Fuyu'
Persimmon. Korean J. Hort. Sci. Technol., 28: 757-761.
Knavel, D.E. and T.R. Kemp. 1973. Ethephon and CPTA on color development in bell
pepper fruits. Hort. Sci., 8: 403-404.
Kudachikar, V.B., S.G. Kulkarni, M.N.K. Prakash, M.S. Vasantha, B.A. Prasad and
K.V.R Ramana, 2001. Physico-chemical changes during maturity of mango
(Mangifera indica L.) Variety "Neelum" J. Food Sci. Technol., 38: 540-542.
Kulkarni, S.G., V.B. Kudachikar, M.S. Vasantha, M.N.K. Prakash, B.A. Prasad and
K.V.R. Ramana. 2004. Studies on effect of ethrel dip treatment on the ripening
behaviour of mango (Mangifera indica, L.) variety „Neelum‟. J. Food Sci.
Technol., 41: 216-220.
Lambiote, B. 1982. Some aspects of the role of dates in human nutrition. First
International Symposium on Date palm. King Faisal University, Saudi Arabia,
March, 23-25.
Larrigaudiere, C., E. Pinto and M. Vendrell, 1996. Differential effects of ethephon and
seniphos on color development of „Starking Delicious‟ apple. J. Am. Soc. Hort.
Sci., 121: 746-750.
Lemaux, G. 1999. Plant Growth Regulator and Biotechnology: Western Plant Growth
Regulator Society Presentation Anaheim CA.
Lewicki, P.P. 1998. Some remarks on rehydration of dried foods. J. Food Eng., 36: 81-87.
Li, Z., S. Sugaya, H. Gemma and S. Iwahori. 2002. Flavonoid biosynthesis and
accumulation and related enzyme activities in the skin of „Fuji‟ and „Orin‟
apples during their development. J. Jpn. Soc. Hort. Sci., 71: 317-321.
203
Lieberman, A. 1979. Biosynthesis and action of ethylene. Ann. Rev. Plant Physiol., 30:
533-591.
Lin, Z.F., S.L. Zhong and D. Grierson, 2009. Recent advances in ethylene research. J.
Exp. Bot., 60: 3311-3336.
Lippert, F. and M.M. Blanke. 2004. Effect of mechanical harvest and timing of 1-MCP
application on respiration and fruit quality of European plums (Pyrus
domestica L.). Postharvest Biol. Technol., 34: 305-311.
Lipton, W.J. 1990. Postharvest biology of fresh asparagus. Hort. Rev., 12: 69-155.
Liu, H., Y. Cao, W. Huang, Y. Guo and Y. Kang. 2013. Effect of ethylene on total
phenolics, antioxidant activity, and the activity of metabolic enzymes in mung
bean sprouts. Eur. Food Res. Technol., 237: 755-764.
Lizada, C. 1993. Mango. In: Seymour, G.B., Taylor, J.E., and Tucker, G.A. (Eds.)
Biochemistry of Fruit Ripening. Chapman and Hall, London, 255-271.
Lombard, P.J., J.A. Viljoen, E.E. Wolf and F.J. Calitz. 2004. The effect of ethephon on
berry colour of „Flame Seedless‟ and „Bonheur‟ table grapes. S. Afr. J. Enol.
Viticul., 25: 1-12.
Looney, N.E. 1998. Plant bio-regulators in fruit production: an overview and outlook. J
Korean Soc. Hort. Sci., 39: 125-128.
Lopez, S., J.V. Maroto, A. San-Bautista, B. Pascual and J. Alagarda. 2000. Qualitative
changes in pepino fruits following pre-harvest applications of ethephon. Sci.
Hort., 83: 157-164.
Lunde, P. 1978. A History of Dates. Saudi Aramco World, 29: 176-179.
Lurie, S. and A. Nussinovich. 1996. Compression characteristics firmness, and texture
perception of heat treated and unheated apples. Int. J. Food Sci. Technol., 31:
1-5.
Lurie, S. and J.D. Klein. 1990. Heat treatment on ripening apples: Differential effect on
physiology and biochemistry. Physiol. Plant, 78: 181-186.
Lurie, S.1998. Postharvest heat treatment review. Postharvest Biol. Technol. 14: 257-269.
Maillard, M.N. and C. Berset. 1995. Evolution of antioxidant activity during kilning: role
of insoluble bound phenolic acids of barley and malt. J. Agric. Food Chem., 43:
1789-1793.
Malik, A.U., Z. Singh and S.S. Dhaliwal. 2003. Exogenous application of putrescence
affects mango fruits quality and shelf life. Acta Hort., 628: 121-27.
204
Malundo, T.M.M., R.L. Shewfelt, G.O. Ware and E.A. Baldwin. 2001. Sugars and acids
influence flavor properties of mango (Mangifera indica L.). J. Amer. Soc. Hort.
Sci., 126: 115-21.
Mann, S.S. 1985. Effect of ethylene and acetylene on the ripening of mango fruits. Acta
Hort., 158: 409-412.
Marin-Rodriguez, M.C., J. Orchard, and G.B. Seymour. 2002. Pectate lyases, cell wall
degradation and fruit softening. J. Exp. Bot., 53: 2115-2119.
Marlett, J.A., M.I. McBurney and J.L. Slavin. 2002. Position of the American Dietetic
Association: Health implications of dietary fibre. J. Am. Diet Assoc., 102: 993-
1000.
Marrero, A. and R.E. Paull. 1998. Physiological effects of hot water treatments on banana
fruits. Acta Hort., 464: 518-518.
Marzouk, H.M., A.M. El-Salhy, H.A. Abdel-Galil and A.E. Mahmoud. 2007. Yield and
fruit quality of some date palm cultivars in response to some flower thinning
rates. Fourth Symposium on Date palm in Saudi Arabia. King Faisal Univ., Al-
Hassa, 5-7 May, P. 110.
Maximos, S.E., A.B.A. Aziz, I. M. Desouky and N.S. Antoun, 1980. Effect of GA3 and
ethephon on the yield and quality of Seewy date fruits. Moshtohor. Ann. Agri.
Sci., 12: 251-262.
Mazumdar, B.C. and D.N.V. Bhatt. 1976. Effects of pre-harvest application of GA and
Ethrel on sweet orange. Prog. Hort., 8: 89-91.
Mcdonald, R.E., T.G. Mccollum and E.A. Baldwin. 1999. Temperature of water
treatments influences tomato fruit quality following low temperature storage.
Postharvest Biol. Technol., 16: 147-155.
Mc-Glasson, W.B. 1985. Ehylene and fruit ripening. HortScience, 20: 51-54.
Messaïtfa, A. 2008. Fluoride contents in ground waters and the main consumed foods
(dates and tea) in Southern Algeria region. Environ. Geol., 55: 377-383.
Mignani, I., L.C. Greve, R. H.U. Ben-Ari and C.L. Stotz. 1995. The effect of GA3 and
divalent cations on aspects of pectin metabolism and tissue softening in
ripening tomato pericarp. Physiol. Plant, 93: 108-115.
Mikki, M.S. 1998. Present status and future prospects of dates and date industry in Saudi
Arabia. In: M. Al-Afifi, M and A. Al-Badawi (Eds.), Proceedings of the First
International Conference on Date Palm, Al Ain, United Arab Emirates. 8-10
March, P. 469-507.
205
Miller, C.J., E.V. Dunn and I.B. Hashim. 2003. The glycaemic index of dates and
date/yoghurt mixed meals. Are dates “the candy that grows on trees”? Eur. J.
Clin. Nutr., 57: 427-430.
Mirza, A.K. and S. Meraj-ud-Din. 1988. Effect of chemical treatment on the composition
of date cultivars. Sarhad J. Agric., 4: 435-442.
Mohamed, A.E. 2000. Trace element levels in some kinds of dates. Food Chem., 70: 9-
12.
Morgan, D.C., C.J. Stanley, R. Volz and I.J. Warrington. 1984. Summer pruning of
„Gala‟ apple: the relationships between pruning time, radiation penetration, and
fruit quality. J. Am. Soc. Hort. Sci., 109: 637-642.
Morrison, J.C. and A.C. Noble. 1990. The effects of leaf and cluster shading on the
composition of Cabernet Sauvignon grapes and on fruit and wine sensory
properties. Amer. J. Enol. Viticul., 41: 193-200.
Morton, J.F. 1987. Fruits of Warm Climates; Florida Flair Books: Miami, USA, P. 9.
Mostafa, R.A.A. and M.M. El. Akkad. 2011. Effect of Fruit Thinning Rate on Yield and
Fruit Quality of Zaghloul and Haiany Date Palms. Aust. J. Basic App. Sci., 5:
3233-3239.
Mougheith, M.G. and G.I. El-Banna. 1974. Effect of ethrel spray on maturation of Sultani
fig. Ann. Agric. Sci., 2: 100-113.
Mougheith, M.G. and L.A. Hassaballa. 1979. Effect of pre-harvest spray of some growth
regulating substances on yield and fruit characteristics of Hayany date cultivar.
Research Bulletin, Faculty of Agriculture, Ain-Shams University, P. 21.
Moustafa, A.A. 1993. Effect of fruit thinning on yield and fruit quality of Seewy date
palms under El-Fayoum Governorate conditions. The Third Symposium on the
date palm in Saudi Arabia. King Faisal Univ, Al-Hassa. Vol. 1. January 17-20.
Mrak, E.M., H.J. Phaff, R.L. Perry, G.L. Marsh and C.D. Fisher. 1946. Fruit dehydration.
California Univ. Agricultural Experiment Station Bulletin 698. Berkeley, Calif.
Murphey, A.S. and D.R. Dilley. 1988. Anthocyanin biosynthesis and maturity of
„McIntosh‟ apples as influenced by ethylene releasing compounds. J. Am. Soc.
Hort. Sci., 113: 718-723.
Musa, S.K. 2001. Early ripening of dates using ethrel, p. 36-46. In: M. Al-Afifi and A.
Al-Badawi (eds.). New Dimensions and Challenges for Sustainable Date Palm
Production: From Farm to Fork. Second International Date Palm Conference,
Al-Ain, U.A.E., 25-27 March
206
Mustafa, A.B., D.B. Harper and D.E. Johnston. 2006. Biochemical changes during
ripening of some Sudanese date varieties. J. Sci. Food Agri., 37: 43-53.
Myers, S.C., A. King and A.T. Savelle, 1993. Bloom thinning of „Wimblo‟ peach and
„Fantasia‟ nectarine with monocarbamide dihydrogensulfate. HortScience, 28:
616-617.
Myhara, R.M., J. Karkalas and M.S. Taylor. 2000. The composition of maturing Omani
dates. J. Sci. Food Agric., 79: 1345-1350.
Naik, D.M., V.G. Mulekar, C.G. Chandel and B.M. Kapse. 1993. Effect of pre-packaging
on physico-chemical changes in tomato (Lycopersicon esculentum Mill.) during
storage. Indian Food Packer.
Najeh, D., T. Taher and B. Kacem.1999. Tunisian Deglet Noor dates ripening, processing
and storage. Ciheam-Iamc., 179-184.
Nikolaou, N., E. Zioziou, D. Stavrakas and A. Patakas. 2003. Effects of ethephon,
methanol, ethanol and girdling treatments on berry maturity and colour
development in Cardinal table grapes. Austr. J. Grape Wine Res., 9: 12-14.
Nittaya, U., T.K. Matsumoto, M.M. Wall and K. Seraypheap. 2011. Changes in
antioxidants and fruit quality in hot water-treated „Hom Thong‟ banana fruit
during storage. Sci. Hort., 130: 801-807.
Nixon, R.W. 1951. The date palm: "Tree of Life"in the subtropical deserts. Econ. Bot., 5:
274-301.
Nixon, R.W. and J.B. Carpenter. 1978. Growing dates in the United States. United States
Department of Agriculture Bulletin no. 207, U.S. Department of Agriculture,
Washington, DC.
Nodiya, M.G. and V.E. Mikaberidze. 1991. Effect of ethylene-producing agents and
gibberellic acid on ripening and quality of Unshiu mandarins. Subtropicheskie-
K;ul‟tury, 4: 85-89.
Olaiya, C.O. and O. Osonubi. 2009. Effects of pre-sowing seed treatments on tomato
Lycopersicon esculentum (L.) Mill) seedling emergence. Int. J. Eng. Technol.,
1: 321-323.
Olorunda, A.O., O.C. Aworth and C.N. Onuoha. 1990. Upgrading quality of dried
tomato: Effects of drying methods, conditions and pre-drying treatments. J. Sci.
Food Agric., 52: 447-54.
Padmini, S. and T.N. Prabha. 1997. Biochemical changes during acetylene-induced
ripening in mangoes (var. Alphonso). Tropical Agric., 74: 265-271.
207
Park, S.J., D.S. Chung, S.S. Hong and Y.B. Kim. 1998. Application of a simple ethylene
generating kit for removal of astringency and softening of persimmon
(Diospyros kaki, Thumb). J. Korean Soc. Hort. Sci., 39: 727-731.
Prasanna, V., T.N. Prabha, and R.N. Tharanathan. 2007. Fruit Ripening Phenomena–An
Overview. Critical Rev. Food Sci. Nutr., 47: 1-19.
Profio, F.D., G. Andrew, Reynolds1 and A. Kasimos. 2012. Canopy Management and
Enzyme Impacts on Merlot, Cabernet franc, and Cabernet Sauvignon. I. Yield
and Berry Composition. Amer. J. Enol. Viticul., 63: 325-332.
Prohens, J., J.J. Ruiz and F. Nuez. 1999. Yield, earliness and fruit quality of pepino
clones and their hybrids in the autumn-winter cycle. J. Sci. Food Agric., 79:
341-346.
Pudmini, S. and T.N. Prabha. 1997. Biochemical changes during acetylene-induced
ripening in mango (var. Alphorns). Trop Agric. (Trinidad), 74: 265-271.
Puech, A.A., C.A. Rebeiz and J.C. Crane. 1976. Pigment changes associated with
application of ethephon (2-Chloroethyl) phosphonic Acid) to fig (Ficus carica
L.) fruits. Plant Physiol., 57: 504-509.
Purandhare, N.D., D.M. Khedkar and M.B. Sontakke. 1992. Physico-chemical changes
during degreening in sweet orange. South Indian Hort., 40: 128-132.
Puri, A., R. Sahai, K.L. Singh, R.P. Saxena, J.S. Tandon and K.C. Saxena. 2000.
Immunostimulant activity of dry fruits and plant materials used in Indian
traditional medical system for mothers after childbirth and invalids. J. Ethno-
pharmacology, 71: 89-92.
Rajwana, I.U., A.U. Malik, A.S. Khan, B.A. Saleem and S. Ahmad. 2010. A new mango
hybrid shows better shelf life and fruit quality. MSc. Thesis Uni. College of
Agric, Bahauddin Zakariya Uni, Multan, Pakistan.
Ramana, K.V.R., S. Saroja, G.R. Setty, A.M. Nanjundaswamy and N.V.N. Moorthy.
1973. Preliminary studies to improve the quality of Coorg monsoon mandarin.
Indian Food Packer, 27: 5-9.
Ratti, C. 2001. Hot air and freeze-drying of high-value foods: A review. J. Food Eng., 49:
311-319.
Riad, M. 2006. The date palm sector in Egypt. CIHEAM-Options Mediterraneanes, 45-
53.
Rohani, A. 1988. Date palm; Tehran University Publication Center: Tehran, Iran, p. 292.
208
Rohani, A., W.A. Nazni, L.V. Ngo, J. Ibrahim and H.L. Lee. 1997. Adulticidal properties
of the essential extracts of some Malaysian plants on vector mosquitoes.
Tropical Biomedicine, 14: 5-9.
Ross, E.B. 1993. Controlling Growth of Bearing Apple Trees with Ethephon. Hort. Sci.,
28: 1103-1105.
Rouhani, I. and A. Bassiri. 1977. Effect of ethephon on ripening and physiology of date
fruits at different stages of maturity. J. Hort. Sci., 52: 289-197.
Ruck, J.A. 1961. Chemical method for analysis of fruit and vegetable products. Res. Sta.
Summerland., Res. Branch, Canada. Dept. of Agri. No. 1154.
Sahari, M.A., M. Barzegar and R. Radfar. 2007. Effect of varieties on the composition of
dates (Phoenix dactylifera L.). Food Sci. Technol. Int., 13: 269-275.
Saheeh Bukhaari. 2001. “Hadith”. Kademi Kitab Khana, Karachi, Publisher (in Arabic).
Vol. 2. P. 181.
Saleem, S.A., A.K. Baloch and M.K. Balocch. 2005. Accelerated ripening of Dhakki
dates by artificial means: ripening by acetic acid and sodium chloride. J. Food
Eng., 70: 61-66.
Saleem, S.A., M.K. Baloch, K. Ahmad and A.K. Baloch. 2002. Effect of ripening by
microwave radiation on quality of Dhakki dates. J. Biol. Sci., 2: 238-242.
Samarawira, I. 1983. Date Palm, Potential Source for Refined Sugar. Econ. Bot., 37: 181-
186.
Samavi, H. 1998. Determination of the best thinning method of Mordasang date cultivar.
Final Report of Research Design. Agricultural Research Center of Hormozgan,
Bandar Abbas, Iran.
Sandhu, S.S., S.S. Thind and J.S. Bal. 1989. Effect of pre-harvest spray of ethephon on
size, quality and ripening of ber (Ziziphus mauritiana Lamk.) Cv. Umran.
Indian J. Hort., 46: 23-27.
Sanghvi, K.U. and Patil, A.V. 1983. Effect of Ethrel on nucellar Mosambi fruits (C.
sinensis Osbeck). Proc. Int. Citrus Symposium, 17-22 December, Bangalore,
Hort. Soc. India, P. 322-325.
Sarig,Y. 1989. An integrated mechanical system for date orchard operation, ASAE P. 89-
1069.
Sauer, J. 1993. Phoenix-Date palms. In historical geography of crop plants. Boca Raton,
FL: CRC Press. P. 182-186.
209
Sawaya, W.N. J.K. Khalil, W.N. Safi and A. Al-Shalhat. 1983. Physical and chemical
characterization of the Saudi date cultivars at various stages of development.
Can. Ins. Food Sci. Technol. J., 16: 87-91.
Sayyahpoor, H. 2002. Determination of the best thinning method of Sayer date cultivar.
Final Report of Research Design. Date Palm & Tropical Fruits Research
Institute of Iran, Ahwaz, Iran.
SBI [Sindh Board of Investment]. 2010. Date‟s Hydration and De-hydration Plant. Sindh,
Pakistan.
Selvam, A.B.D. 2008. Inventory of vegetable crude drug samples housed in botanical
survey of India, Howrah. Pharmacognosy Rev., 2: 61-94.
Sergent, E., B. Schaffer, S.P. Lara and E. Willis. 1993. Effect of ethephon on mango
(Mangifera indica L.) fruit quality. Acta Hort., 341: 510-517.
Shahidi, F. and M. Naczk. 2004. Phenolics in food and nutraceuticals. Boca Raton, FL:
CRC Press.
Shahnawaz, M., S.A. Sheikh, A.A. Panwar, S.G. Khaskheli and F.A. Awan. 2012. Effect
of hot water treatment on the chemical, sensorial properties and ripening
quality of Chaunsa Mango (Mangifera indica L.). J. Basic App. Sci., 8: 328-
333.
Shamshiri, M.H. and M. Rahemi. 1999. Effect of ethephon, sodium chloride and acetic
acid on quality of Muzafati date fruits. Iranian J. Agri. Sci., 29: 777-785.
Shiota, M., M.C. Moore, P. Galassetti, M. Monohan, D.W. Neal, G.I. Shulman and A.D.
Cherrington. 2002. Inclusion of low amounts of fructose with an intraduodenal
glucose load markedly reduces postprandial hyperglycemia and
hyperinsulinemia in the conscious dog. Diabetes, 51: 469-478.
Sims, W.L., H.B. Collins and B.L. Gledhill. 1970. Ethrel effects on fruit ripening of
peppers. Calif. Agric., 24: 4-5.
Singh, H.P., K.C. Srivastava, K. Ganapathy, D.P. Muthappa and G.S. Randhawa. 1978.
Effect of ethephon (2-chloroethyl phosphonic acid) on post-harvest degreening
of mandarin and sweet orange. Vatika, 1: 56-63.
Singh, Z., J. Janes, Z. Singh, R. Ben-Arie and S. Philosoph-Hadas. 2001. Effects of
postharvest application of ethephon on fruit ripening, quality and shelf life of
mango under modified atmosphere packaging. Acta Hort., 553: 599-602.
Sisler, E. and S. Fa-Yang. 1984. Ehylene, the gaseous plant hormone. Biol. Sci. 34: 234-
238.
210
Smith, L.G. 1991. Effects of ethephon on ripening and quality of freshmarket pineapples.
Aus. J. Exp. Agric., 31: 123-127.
Smithyman, R. P., G.S. Howell and D.P. Miller. 1998. The use of competition for
carbohydrates among vegetative and reproductive sinks to reduce fruit set and
botrytis bunch rot in seyval blanc grapevines.Am. J. Enol. Viticul., 49: 163-
170.
Soliman, S.S. and M.M. Harhash, 2012. Effects of strands thinning on yield and fruit
quality of Succary date palm. African J. Biotechnol., 11: 2672-2676.
Soliman, S.S., R.S. Al-Obeed and M.M. Harhash. 2011. Effects of bunch thinning on
yield and fruit quality of Khalas date Palm cultivar. World Appl. Sci. J., 12:
1187-1191.
Soni, S.L. and S.L. Ameta. 1983. Effect of pre-harvest application of ethrel on coloration
and physico-chemical composition of grapefruit. Proc. Int. Citrus Symposium
Bangalore, Hort. Soc. India, P. 309-315.
Sonkar, R.K. and M.S. Ladaniya. 1999. Effect of pre-harvest spray of ethephon, Calcium
acetate and Carbendazim on rind color, Abscission and shelf life of Nagpur
Mandrin (Citrus reticulate). Indian J. Agric. Sci., 69: 130-135.
Srinivasa, P.C., R. Baskaran, M.N. Ramesh, K.V.H. Prashanth and R.N. Haranathan,
2002. Storage studies of mango packed using biodegradable chitosan film. Eur.
Food Res. Tech., 215: 504-508.
Stanly, D.W., M.C. Bourne, A.P. Stone and W.V. Wismer. 1995. Low temperature
blanching effects on chemistry, firmness and structure of canned green beans
and carrots. J. Food Sci., 60: 327-333.
Steel, R. G. D., J. H. Torrie and D. A. Dickey. 1997. Principles and Procedures of
Statistics. New York: McGraw-Hill.
Steenkamp, J., K.L. Blommaert and J.H. Jooste. 1977. Invloed van ethephon op die
rypwording van druiwe (Vitis vinifera L. „Barlinka‟). Agroplante, 9: 51-54.
Stewart, I. 1977. Citrus color-A review. Proc. Int. Citrus Congress, Florida, Vol. 1, P.
308-311.
Suresh, N. and S. Zora. 2003. Pre storage ethrel dip reduces chilling injury, enhances
respiration rate, ethylene production and improves fruit quality of „Kensington‟
mango. J. Food Agric. Environ., 1: 93-97.
211
Szyjewicz, E., N. Rosner and M.W. Kliewer. 1984. Ethephon (2-chloroethylphosphonic
acid, Ethrel, CEPA) in viticulture: A review. Amer. J. Enol. Viticul., 35: 117-
123.
Tafti, A.G. and M.H. Fooladi. 2004. A study on the physico-chemical properties of
Iranian Shamsaei date at different stages of maturity. World J. Dairy Food Sci.,
1: 28-32.
Tahraoui, A., J. El-Hilaly, Z.H. Israili and B. Lyoussi. 2007. Ethnopharmacological
survey of plants used in the traditional treatment of hypertension and diabetes
in southeastern Morocco (Errachidia province). J. Ethno-pharmacology, 110:
105-117.
Taira, S., T. Satoh and S. Watanabe. 1991. Removal of the astringency taste from
persimmons and softening following treatment. Agric. Hort., 66: 1401-1404.
Tamura, F., K. Tanabe, A. Hai and M. Hasegawa. 1999. Characteristics of acetaldehyde
accumulation and removal of astringency with ethanol and carbon dioxide
treatments in “Saijo” persimmon fruit. J. Japanese Soc. Hort. Sci., 68: 1178-
1183.
Tapas, A.R., A.M. Sakarkar and R.B. Kakde. 2008. Flavonoids as nutraceuticals: A
review. Tropical J. Pharmaceutical Res., 7: 1089-1099.
Tavakkoli, A., E. Tafazoli and M. Rahemi. 1994. Comparison of the effects of hand
thinning and chemical thinning on fruit quantity and quality and alternate
bearing of Shahani date cultivar. Proc. the 1st Date Seminar. Boushehr. Iran
24-27 January. P. 107-118.
Theologis, A. 1993. One rotten apple spoils the whole bushel: the role of ethylene in fruit
ripening. Cell, 70: 181-184.
Thomas, P. and M.S. Oke. 1980. Vitamin C content and distribution in mangoes during
ripening. J. Food Technol., 15: 669-72.
Tian, M.S., A.B. Woolf, J.H. Bowen and I.B. Ferguson. 1996. Changes in color and
chlorophyll fluorescence of broccoli florets following hot water treatment. J.
Amer. Soc. Sci., 121: 310-313.
Tucker, G.A. and D. Grierson. 1987. Fruit ripening. In: Davies, D. (Ed.). The
Biochemistry of Plants. Academic Press Inc., New York. 12: 265-319.
UN, 2003. Organic Fruit and Vegetables from the Tropics. United Nations Conference on
Trade & Development. New York and Geneva.
212
Valley, S. 2000. Sun-dried tomato-the valley sun difference. Newman, Calif. Available
from: http://www.valleysun.com. Accessed 2001 Jan 1.
Van Schaftingen, E. and D.R. Davies. 1991. Fructose administration stimulates glucose
phosphorylation in the livers of anesthetized rats. Faseb J., 5(3): 326-330.
Vandercook, C.E. S. Hasegawa 1980. V.P. Maier. Dates. In: Nagy, S; Shaw, P.E. (Eds.)
Tropical and Subtropical Fruits. AVI Publishing Co: Westport, CT, P. 506-541.
Vandercook, C.E., S. Hasegawa, and V.P. Maier.1980. Dates, p. 506-541. In: S. Nagy and
P.E. Shaw (Eds.). Tropical and subtropical fruits: Composition, properties, and
uses. AVI Pub-lishing Company, Westport, CT.
Vayalil, P.K., 2012. Date Fruits (Phoenix dactylifera Linn): an emerging medicinal food.
Crit. Rev. Food Sci. Nutr., 52: 249-271.
Walker, A.J. and L.C. Ho. 1977. Carbon translocation in tomato-effects of fruit
temperature on carbon metabolism and rate of translocation. Ann. Bot., 41:
825-832.
Wall, M.M. 2004. Ripening behaviour and quality of `Brazilian' bananas following hot
water immersion to disinfest surface insects. HortScience, 39: 1349-1353.
Wang, Z.Y. and D.R. Dilley. 2001. Aminoethoxyvinylglycine, combined with ethephon,
can enhance red color development without over-ripening apples. HortScience,
36: 328-331.
Warner, H.L. and A.C. Leopold. 1967. Plant growth regulation by stimulation of ethylene
production. Biol. Sci., 17: 722.
Watada, A.E., R.C. Herner, A.A. Kader, R.J. Romani and G.L. Staby. 1984. Terminology
for the description of developmental stages of horticultural crops. Hort. Sci.,
19: 20-21.
Watford, M. 2002. Small amounts of dietary fructose dramatically increase hepatic
glucose uptake through a novel mechanism of glucokinase activation. Nutr.
Rev., 60: 253-257.
Whale, S.K., Z. Singh, M.H. Behboudian, J. Janes and S.S. Dhaliwal. 2008. Fruit quality
in „Cripp‟s Pink‟ apple, especially colour, as affected by pre-harvest sprays of
aminoethoxyvinylglycine and ethephon. Sci. Hort., 115: 342-351.
White, P.J. 2002. Recent advances in fruit development and ripening: an overview. J.
Exp. Bot., 53: 1995-2000.
213
Wicks, A.S. and W.M. Kliewer. 1983. Further investigations into the relationship
between anthocyanins, phenolics and soluble carbohydrates in grape berry
skins. Amer. J. Enol. Viticul., 34: 114-116.
Wills, R.B.H. and G.H. Kim. 1995. Effect of ethylene on post-harvest life of strawberries.
Post-harvest Biol. Technol., 6: 249-255.
Worku,, Z., R.C. Herner, and R.L. Carolus. 1975. Effect of stage of ripening and
ethephon treatment on color content of paprika pepper. Sci. Hort. 3: 239-245.
Wrigley, G. 1995. Date palm, In: J. Smartt and N.W. Simmonds (Eds.). Evolution of crop
plants. 2nd ed. Longman Group, Essex, UK. P. 399-403.
Yadava, L.P., R. Pati and V.K. Gupta. 2008. Effect of paclobutrazol and ethephon on the
biochemical constituents of cape gooseberry (Physalis peruviana L.). Asian J.
Biol. Sci., 3: 124-126.
Yang, S.P. 1985. Biosynthesis and action of ethylene. HortScience, 20: 41-45.
Yong, R., O. John, W.C. Cooper and J.J. Smooth. 1970. Pre-harvest sprays with 2-
chloroethylphosphonic acid to degreen „Robinson‟ and „Lee‟ tangerine fruits.
Hort. Sci., 5: 268-279.
Yousif, A.K., A.F. Alshaawan M.Z. Mininah and S.M. Eltaisan. 1987. Processing of date
preserve, date jelly and date butter. Date Palm J., 5: 73- 86.
Yuzo, S. and Y. Tomoya. 2002. Effect of ethephon agent spray on fruit quality of 'la
France'. Tohoku Agric. Res., 55: 161-162.
Zaid, A. 1999. Date palm Cultivation. FAO. Publication. No. 287.
Zaid, A. and E.J. Arias-Jimenez, 2002. Date Palm Cultivation. FAO Plant Production and
Protection Paper 156 (Rev. 1). FAO, Rome, Italy.
Zare, Z., M. Sohrabpour, T.Z. Fazeli and K.G. Kohan. 2002. Evaluation of invertase (B-
fructo furanosidase) activity in irradiated Mazafati dates during storage. Radiat.
Phys. Chem., 65: 289-291.
Zohary, D. and M. Hopf. 2000. Domestication of plants in the Old World. The origin and
spread of cultivated plants in West Asia, Europe, and the Nile Valley. Oxford
University Press, Oxon, UK.