nicotiana tabacum) seedling production in zimbabwe
TRANSCRIPT
SOILLESS MEDIA FOR TOBACCO (NICOTIANA TABACUM) SEEDLING
PRODUCTION IN ZIMBABWE - WIDENING THE OPTIONS
CORESTA CONGRESS 2014
TOBACCO RESEARCH BOARD
KUTSAGA
Chapman Koga
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Presentation Outline
1. Introduction
2. Composting process
3. Float system trial 1
4. Float system trial 2
5. Float system trial 3
6. Conclusion & recommendation
7. Acknowledgements
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Introduction • Healthy growing seedlings - basis of a good
tobacco crop.
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Introduction • Healthy growing seedlings - basis of a good
tobacco crop.
• Methyl bromide fumigant and other fumigants
• The best alternative is the use of soilless media.
• Gromix®, derived from pine bark, is the most common medium used.
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• Sole source of pine bark in Zimbabwe is the timber producing eastern districts of the country
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• It is also a finite source • Ideal medium should also have high CEC, high porosity (for reduced spiral rooting), and produce uniformly grown seedlings.
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The main objective of this study was, therefore, to develop alternative, cost effective media options for tobacco seedling production
Objective
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Materials and Methods A) Composting of organic substrates
1. 1) Maize cobs and groundnut shell plant residues ground to produce coarse to fine particles for effective microbial decomposition, placed in 1 m3 wooden boxes
2. 2) Substrate samples were analyzed for organic C and total N to determine the C:N ratio of each material.
3. 3) The moisture content was maintained at 60% throughout the composting trial.
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Methodology... cont’d
4. Ammonium nitrate added - suitable nutrient balance for net mineralization of organic materials
5. Pile temperature measurements on day one and thereafter at 3-day intervals using Hobo Series 400 temperature probes
6. Microbial analyses performed after 12 weeks of composting
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Methodology...cont’d B) Float system
1. Float trays (200- and 242-cells.
2. Black plastic sheeting (250 µm) and water level (10-12 cm).
3. Media treatments combinations
4. Fertilizer – Basal Hydrofert (20:10:20)
Ammonium nitrate (100 mg NL-1 of water)
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Measurements
1. Germination and spiral roots counts from 14 DAS
2. Stem height and diameter at 12 WAS
3. Dry mass of shoots and roots at 12 WAS
4. Percent transplantable seedlings
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Data Analysis
Analysis of Variance (ANOVA) used to test the significance of treatment effects and the LSD was used for mean separation
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Results and discussion
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Parameter Maize cobs Groundnut shells
Before
composting
After
composting
Before
composting
After
composting
pH 4.53 6.13 5.22 5.49
Ca 0.06 0.16 0.16 0.35
Mg 0.07 0.11 0.12 0.11
Na 0.01 0.03 0.01 0.02
K 0.95 0.71 1.15 0.19
Total N 0.60 3.09 0.89 2.25
Total C 98.05 95.19 94.68 90.70
C/N ratio 164:1 31:1 106:1 40:1
Composting trial results
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Type of bacteria Type of organic material
Maize cobs Groundnut shells
Bacillus (cfu g-1) 96, 000, 000 330, 000
Streptococcus (cfu g-1) 40 10
010203040506070
1 2 3 4 5 6 7 8 9 10 11 12
Tem
pe
ratu
re o
C
Weeks after commencement
Maize cobs
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• The higher microbial populations in maize cobs may have been due to a higher C: N ratio (164: 1) compared to that in the groundnut shells (106:1).
• The higher temperatures in maize cobs was due to elevated micro-floral counts which encouraged increased energy-releasing metabolic processes.
Summary of Results
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Experiment 1
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Treatments for the float bed trial 1. 50% Maize cobs + 50% Sand 2. 50% Groundnut shells + 50% Sand 3. 50% Pine bark + 50% Sand 4. 50% Coal rubble + 50% Sand 5. 50% Cattle manure + 50% Sand 6. 50% Bean Husks + 50% Sand 7. 75% Maize cobs + 25% Sand 8. 75% Groundnut shells + 25% Sand 9. 100% Pine bark (Control) 10. 100% Coal rubble 11. 100% Cattle manure
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0
20
40
60
80
100
120
140
160
180
200
14 DAS 21 DAS 28 DAS 35 DAS 42 DAS
Ge
rmin
atio
n/
20
0 c
ell
tray
Days after sowing
50% Maize cobs + 50% Sand
50% Groundnut shells + 50% Sand
50% Pine bark + 50% Sand
50% Coal rubble + 50% Sand
50% Cattle manure + 50% Sand
50% Bean Husks + 50% Sand
75% Maize cobs + 25% Sand
75% Groundnut shells + 25% Sand
100% Pine bark (Control)
100% Coal rubble
100% Cattle manure
Float system results
p<0.001
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020406080
100120140160180200
Ste
m h
eig
ht,
mm
Seedling quality measurements
p=0.004
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020406080
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Ste
m h
eig
ht,
mm
Seedling quality measurements
p=0.004
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Discussion
•Bean husks and cattle manure media were phytotoxic to tobacco seedlings not suitable media.
•High EC values in bean husks and cattle manure treatments resulting in salt injury.
•Germination and survival in coal rubble, maize cobs and groundnut shell media were all comparable to the pine bark media.
•Thus these substrates are potential alternatives to pine bark.
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Experiment 2
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Treatments 1. 100% Pine sawdust
2. 75% Pine sawdust
3. 50% Pine sawdust
4. 25% Pine sawdust
5. 100% Gum sawdust
6. 75% Gum sawdust
7. 50% Gum sawdust
8. 25% Gum sawdust
9. 100% Pine bark (Standard)
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0
10
20
30
40
50
60
70
80
90
100
10 DAS 14 DAS 21 DAS 28 DAS
% g
erm
inat
ion
Days after sowing
100% Pine sawdust
75% Pine sawdust*
50% Pine sawdust*
25% Pine sawdust*
100% Gum sawdust
75% Gum sawdust*
50% Gum sawdust*
25% Gum sawdust*
100% Pine bark (Standard)
Germination and survival
p<0.001
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0
10
20
30
40
50
60
% t
ran
spla
nta
ble
Transplantable seedlings
p<0.001
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0
20
40
60
80
100
120
140
160
Ste
m h
eig
ht,
mm
Seedling quality measurements
p<0.001
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Discussion
• Increasing the percentages of either gum or pine sawdust in mixtures resulted in reduced seedling survival. • However, seedlings from the 25% pine sawdust had an ideal height, making the media suitable for use.
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Experiment 3
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Treatments
1. 100% Pine bark (PB)
2. 100% Vermiculite
3. 100% Pine sawdust
4. 100% Cotton seed Hull
5. 100% Fine sugar cane bagasse
6. 100% Coarse sugar cane bagasse
7. 75% Cotton seed Hull: 25% Pine bark
8. 75% Pine sawdust: 25% Pine bark
9. 75% Fine sugar cane bagasse: 25% Pine bark
10. 75% Coarse sugar cane bagasse: 25% Pine bark
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Treatments…cont’d
11. 50% Cotton seed Hull: 50% Pine bark 12. 50% Pine Sawdust: 50% Pine bark 13. 50% Fine sugar cane bagasse: 50% Pine bark 14. 50% Coarse sugar cane bagasse: 50% Pine bark 15. 25% Cotton seed Hull: 75% Pine bark 16. 25% Pine sawdust: 75% Pine bark 17. 25% Fine sugar cane bagasse: 75% Pine bark 18. 25% Coarse sugar cane bagasse: 75% Pine bark 19. 25% Gum sawdust: 75% Pine bark
20. 25% Vermiculite: 75 Pine bark
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0102030405060708090
% S
urv
ival
Seedling survival at 12 WAS
p<0.001 2014
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020406080
100120140160180200
Ste
m h
eig
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mm
Seedling height measurements
p<0.001
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Discussion
A combination of 50% cotton seed hull and 50% pine bark resulted in quality seedlings.
The vermiculite media was also very good and produced seedlings that were of a significantly better quality than those from the 100% pine bark.
However, the cost of this medium is prohibitive possibility of salt injury
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General conclusion and recommendations
• Composted maize cobs and groundnut shells, cotton seed hull and coal rubble can be used as alternative growing media in the tobacco float seedling production system. • Substrates such as maize cobs and groundnut shells are more cost effective for the predominantly small scale growers. • Coal rubble – abundant waste product of the curing process • It is recommended that future research work explores the possibility of blending some of the most promising soilless media.
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Acknowledgements
1. Tobacco Research Board Management and Staff
2. CORESTA Organising Committee
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Thank you
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