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DRY MATTER ACCUMULATION AND
PARTITIONING OF TWO IMPROVED TARO
(COLOCASIA ESCULENTA (L.) SCHOTT) CULTIVARS
UNDER VARYING NITROGEN FERTILIZATION
RATES IN SAMOA
by
Walter Fa’amatuāinu
A thesis submitted in fulfilment of the
requirements for the Degree of
Master of Agriculture
Copyright © 2016 by Walter Fa’amatuāinu
School of Agriculture and Food Technology Faculty of Business and Economics
University of the South Pacific
August, 2016
iii
DEDICATION
Proverbs 1:7 “The fear of the Lord is the beginning of knowledge”.
Confucius: “Our greatest glory is not in never falling, but in rising every time we fall”.
To my parents (Muliumu Tamāpua Fa’amatuāinu and Fa’amatuāinu Su’ifua
Liumalo) and to my oldest brother Falepāuga Oea Tamāpua (Rest In Peace brother, if
only you could live longer to see what your apprentice has become).
iv
ACKNOWLEDGEMENTS
I am greatly indebted to my supervisor Mr Falaniko Amosa (Lecturer of the Crops
Science division). His invaluable assistance and comments are gratefully
acknowledged during this study and had contributed a lot to my understanding.
Secondly, I am grateful to the Research Division of USP for the Graduate Assistant
Scholarship which provided tremendous financial support for my research. The
support from the Head of the School of Agriculture, Associate Professor Mohammed
Umar and all the staff members of the USP Alafua Campus, who helped me
whenever I asked for support. Special thanks to Ms Roshila Singh who assisted in the
reading and editing of the thesis. Ms Cecilia Amosa for summarising the weather
data, Pakoa Leo, and Sekone Faleao who assisted in the field work. Finally to all
those who are not mentioned here, but contributed to this research project, thank you
very very much.
v
ABSTRACT
The accumulation and partitioning of dry matter in two improved taro cultivars
(Samoa 1 and Samoa 2) were determined to characterise their growth and
development patterns. A split- split-plots experiment in a RCBD design with three
replications was setup to determine the dry matter accumulation and partitioning of
the two cultivars. Each replicate contain two main plots (cultivars) which were split
to accommodate three nitrogen rates (0, 100, 200 kg ha-1). These were further split to
accommodate five sampling (harvest) dates (35, 70, 105, 140, 175 DAP). During six
months, all the data collected from the experiment were analysed using the GenStat
statistical software.
The two cultivars varied in dry matter accumulation to the leaf blades, petioles, roots,
corms and suckers. Also, the dry matter partitioned to the different organs of the taro
cultivars differed with respect to the rate of nitrogen used. The analysis of dry matter
for the cultivars was carried out 35 days after planting (DAP) and continued until the
final harvest six months after planting. During the early growth and development
stages of the two cultivars, the leaves and petioles received greater portions of dry
matter, however later on during the growth period, the corm and suckers dominated.
Even though, the growth and development patterns of Samoa 1 and Samoa 2 were
similar, the total dry matter of Samoa 2 was higher than Samoa 1.
The two cultivars response to the amount of nitrogen applied was different
depending on the taro part involved. The influence of the applied nitrogen was more
profound in the aboveground biomass portions of taro plants during the early stages
of growth which were clearly demonstrated in the pot experiment. In the field
experiment it was observed that increasing the rate of nitrogen enhanced the leaf
blades dry matter (LDM) and petioles dry matter (PDM) of Samoa 2 in contrast to
Samoa 1. Furthermore, the differences between leaf blades, petioles, corm, roots
suckers and total dry matter of Samoa 1 and Samoa 2 as result of the five sampling or
harvest (DAP) were highly significant (P<0.001).
Additionally, the leaf area index (LAI), plant height, number of leaves and suckers of
Samoa 1 and Samoa 2 all increased early in the growth stages until 105 or 140 DAP
before declining at 175 DAP. The difference in plant height, LAI, number of leaves
vi
and suckers were highly significant (P<0.001) between the two cultivars during the
five harvest dates (DAP). The difference in plant height between the two cultivars
were significant (P = 0.04) as result of the nitrogen added and the difference in LAI
between the two cultivars was also significant (P = 0.003).
The pot experiment which was carried out before the field experiment was vital in
determining the responses of the different taro parts against the selected rates
nitrogen (0, 50, 100, 150 and 200 kg ha-1). The statistical analysis showed that the
application of nitrogen caused the LDM, PDM, CDM, RDM, SDM and TDM of
Samoa 1 and Samoa 2 to be significantly different (P < 0.001) from each other.
Moreover, the difference between the physiological characteristics of the two
cultivars such as the LAI, height and number of leaves for the two cultivars were also
statistically significant (P < 0.001)
All in all, as revealed from both the pot and field experiments there were significant
differences between the two cultivars (Samoa 1 and Samoa 2) in terms of their dry
matter accumulations and partitioning as well as other physiological characteristics
such as the LAI and plant height which in turn affected their growth and
development.
vii
LIST OF ABBREVIATIONS, ACRONYMS AND SYMBOLS
CePaCT - The Centre for Pacific Crops and Trees
cm - centimetres
CMD - Corm dry matter
DAP - Days after planting
DM - Dry matter
FAO - Food and Agricultural Organization
FAOSTAT - Food and Agricultural Organization Statistics
ha - Hectare
kg - Kilogram
LAI - Leaf area index
LDM - Leaf blades dry matter
MAF - Ministry of Agriculture and Fisheries (of the Government of Samoa).
mM – millimolar
NPK - Nitrogen phosphorus and potassium
N rates - Nitrogen rates
PDM - Petioles dry matter
RCBD – Randomised complete block design
RDM - Roots dry matter
SAT - Samoan tala (tala = dollar)
SDM - Suckers dry matter
TANSAO - Taro network for Southeast Asia and Oceania
TaroGen - Taro genetic resources
TIP - Taro Improvement Project
TLB - Taro leaf blight
viii
TABLE OF CONTENTS.
DECLARATION OF ORIGINALITY ................................................................................. ii
DEDICATION ........................................................................................................................ iii
ACKNOWLEDGEMENTS ................................................................................................... iv
ABSTRACT .............................................................................................................................. v
LIST OF ABBREVIATIONS, ACRONYMS AND SYMBOLS ....................................... vii
LIST OF FIGURES ................................................................................................................. x
LIST OF TABLES ................................................................................................................ xii
CHAPTER 1 ............................................................................................................................. 1
1.1 Introduction ............................................................................................................... 1 1. 2 Objectives ................................................................................................................. 4
CHAPTER 2 ............................................................................................................................. 6
2.0 Literature Review ...................................................................................................... 6 2.1 Background to Samoa ............................................................................................... 6 2.2 Samoa land use .......................................................................................................... 6 2.3 Samoan soils ............................................................................................................. 7 2.4 Soil nutrients ............................................................................................................. 8 2.5 Taro growth and development .................................................................................. 8 2.6 Dry matter analysis ................................................................................................. 10 2.7 Taro response to applied nitrogen ........................................................................... 10
CHAPTER 3 ........................................................................................................................... 12
3.0 Pot Experiment ........................................................................................................ 12 3.1 Introduction ............................................................................................................. 12 3.2 Materials and Methods ............................................................................................ 13 3.3 Results and Discussions .......................................................................................... 14 3.4 Conclusion .............................................................................................................. 20
CHAPTER 4 ........................................................................................................................... 22
4.0 Field Experiment ..................................................................................................... 22 4.1 Introduction ............................................................................................................. 22 4.2 Materials and Methods ............................................................................................ 23 4.3 Results and Discussions .......................................................................................... 25 4.3.1 Monthly rainfall during field experiment ............................................................. 25 4.3.2 Growth Measurements ......................................................................................... 26
ix
4.3.3 Plant Height .......................................................................................................... 26 4.3.4 Leaf Area Index (LAI) ......................................................................................... 27 4.3.5 Development measurement .................................................................................. 28 4.3.6 Leaf number ......................................................................................................... 28 4.3.7 Sucker Production ................................................................................................ 29 4.3.8 Dry matter accumulation ...................................................................................... 30 4.3.9 Leaf blade (LDM) ................................................................................................ 30 4.4.0 Petiole (PDM) ...................................................................................................... 31 4.4.1 Corm (CDM) ........................................................................................................ 32 4.4.2 Root (RDM) ......................................................................................................... 34 4.4.3 Sucker (SDM) ...................................................................................................... 35 4.4.4 Total (TDM) ......................................................................................................... 36 4.4.5 Dry matter partitioning ......................................................................................... 37 4.4.6 Leaf blades ........................................................................................................... 37 4.4.7 Petioles ................................................................................................................. 38 4.4.8 Corm ..................................................................................................................... 39 4.4.9 Roots .................................................................................................................... 40 4.5.0 Suckers ................................................................................................................. 41
CHAPTER 5 ........................................................................................................................... 42
5.1 General Discussions ................................................................................................ 42 5.2 Conclusion .............................................................................................................. 45
REFERENCES ....................................................................................................................... 48
APPENDICES. ....................................................................................................................... 57
Appendix 1: Nitrogen rates calculations ....................................................................... 57 1.1 Pot Experiment ........................................................................................................ 57 1.2 Field Experiment ..................................................................................................... 57 Appendix 2: Field experiment Layout. ......................................................................... 59 Appendix 3: Pot Experiment Analysis of variance ....................................................... 60 Appendix 4: Field Trial Analysis of variance ............................................................... 71 Appendix 5: Average values for dry matter accumulation and partitioning. ................ 99
x
LIST OF FIGURES
Figure 1: “The effect of five nitrogen rates on the heights (cm) of Samoa 1 and Samoa 2.” ................................................................................................................................. 14
Figure 2: “The changes in LAI for Samoa 1 and Samoa 2 during six months of growth.” .................................................................................................................................... 15
Figure 3: “The effect of five nitrogen rates on the number of leaves of Samoa 1 and Samoa 2.” ................................................................................................................................. 16
Figure 4: “The effect of five nitrogen rates on the LDM and PDM of Samoa 1 and Samoa 2.” ................................................................................................................................. 17
Figure 5: “The effect of five nitrogen rates on the CDM and RDM of Samoa 1 and Samoa 2.” ................................................................................................................................. 18
Figure 6: “The effect of five nitrogen rates on the SDM and TDM of Samoa 1 and Samoa 2.” ................................................................................................................................. 19
Figure 7: “Weekly rainfall recordings at the project site for the eight months from January- August 2015.” ............................................................................................................ 25
Figure 8: “The effect of three nitrogen rates and five harvest dates on the heights (cm) of Samoa 1 and Samoa 2.” .............................................................................................. 26
Figure 9: “The effect five harvest dates on the LAIs of Samoa 1 and Samoa 2.” ................... 27
Figure 10: “The effect of five harvest dates on the number of leaves of Samoa 1 and Samoa 2.” ................................................................................................................................. 28
Figure 11: “The effect of five harvest dates on the number of suckers of Samoa 1 and Samoa 2.” ................................................................................................................................. 29
Figure 12: “The effect of five harvest dates on the LDM of Samoa 1 and Samoa 2.” ............ 30
Figure 13: “The effect of five harvest dates on the PDM of Samoa 1 and Samoa 2.” ............ 31
Figure 14: “The effect of five harvest dates on the CDM of Samoa 1 and Samoa 2.” ............ 32
Figure 15: “The effect five harvest dates on the RDM of Samoa 1 and Samoa 2.” ................ 34
xi
Figure 16: “The effect of five harvest dates on the SDM of Samoa 1 and Samoa 2.” ............ 35
Figure 17: “The effect of five harvest dates on the TDM of Samoa 1 and Samoa 2.” ............ 36
Figure 18: “The effect of five harvest dates on the dry matter partitioned to the leaf blades of Samoa 1 and Samoa 2.” ............................................................................................ 37
Figure 19: “The effect of five harvest dates on the dry matter partitioned to the petioles of Samoa 1 and Samoa 2”. .......................................................................................... 38
Figure 20: “The effect of five harvest dates on the dry matter partitioned to the corms of Samoa 1 and Samoa 2”. ....................................................................................................... 39
Figure 21: “The effect of five harvest dates on the dry matter partitioned to the suckers of Samoa 1 and Samoa 2”. .......................................................................................... 41
xii
LIST OF TABLES
Table 1: “Samoa’s taro breeding programme”........................................................................... 4
Table 2: “The effect of five harvest dates on the dry matter partitioned to the roots (%) of Samoa 1 and Samoa 2” ............................................................................................. 40
1
CHAPTER 1
1.1 Introduction
Taro (Colocasia esculenta), a member of the Araceae family is an ancient crop
widely grown throughout the humid tropics for its edible leaves, petioles and corms
(Lee, 1999; Nath et al., 2013; Rao et al., 2010; Wang, 1983). It was also reported that
rice was first observed in flooded taro paddies (Acabado, 2012; Lebot, 2009). The
taro plant consists of an aboveground (leaf blades and petioles) and belowground
portions (roots and corms). The leaf blades range from 25 to 85 cm in length and 20
to 60cm in width (Lee, 1999). Petioles can reach 200cm in length and claps around
the apex of the corm (FAO, 1999). Taro corms are modified below ground stems
mainly cylindrical in shape while adventitious and fibrous rooting system are found
mostly on the top layers of the soil (Lee, 1999; Onwueme, 1978).
Among the root crops, taro is ranked fifth behind potato, cassava, sweet potato and
yam in terms of global production (Quero-García et al., 2006). The world production
of taro is estimated at 11.8 million tons per annum, with large contributions from
West African countries like Nigeria, Cameroon, Ghana and Ivory Coast (Akwee et
al., 2015). However, Fiji, Tonga and Samoa are ranked second, fifth and sixth
respectively as major exporters of taro (McGregor et al., 2011a). The Pacific Island
countries export around 10,000-12,000 tons of taro annually to New Zealand,
Australia, Japan and the United States of America valued at around 6 million USD
(Akwee et al., 2015; McGregor et al., 2011a).
Taro is cultivated in almost all ecological zones in the Pacific because of its wide
environmental tolerance (Ofori, 2003). It plays a vital role in Pacific Island countries
as a staple food, providing protein, vitamins, minerals and carbohydrates (Onwueme,
1999). In Hawaii, taro is deeply embedded in the local customs and traditions. Taro
is viewed as having a strong connection with the ancestors, thus holding a very high
value in the culture of the Hawaiian people (Rao et al., 2010). Likewise in other
Polynesian Islands like Samoa, taro is mainly associated with traditional social
activities such as weddings, opening of new churches and funerals (Iosefa et al.,
2012). Archaeological excavations in the Solomon Islands found tools dating 28,700
years old that were used in the preparation of taro for consumption (Rao et al., 2010).
2
The excellent teeth observed in early Polynesians is mainly attributed to their
frequent consumption of taro (Lee, 1999).
Historically, agriculture has been the backbone of Samoa’s economy, mainly in
terms of subsistence food supply and export (FAO, 2003; Ullah, 2006). During the
1970s and 1980s agriculture contributed at least 50% of the country’s total gross
domestic product (GDP) (MAF, 2011). By the middle of last century agriculture in
Samoa supported half of the country’s population and farmers working on taro
plantations earned more income than those working on other crops (Hunter et al.,
1998; Mercer and Scott, 1958). Taro is the most important of all vegetable crops in
Samoa, not only as an export commodity but also because its cultural significance
(Hunter et al., 1998; Watters, 1958). Samoa started exporting taro to New Zealand in
1957, followed by exports to Australia and America. The demand for taro in New
Zealand was mainly from expatriate Samoans who migrated there for employment
and educational opportunities (Malaki and William, 1998).
Taro was extensively grown in Samoa as a monocrop in 80% of plantations, and
remaining were intercropped with Cocoa, Coconuts and Banana (Liyanage and
Misipati, 1993). From 1980 to 1993, taro exports grew rapidly, and eventually
becoming Samoa’s largest export earner (McGregor et al., 2011b). The benefits from
taro production were temporarily interrupted by cyclones Ofa in 1990 and Val in
1991, but much worse followed in June 1993, when for the first time the taro leaf
blight (TLB) was detected in Samoa (Hunter et al., 1998).
TLB (Phytophthora colocasiae) was first reported in the 1900’s in South East Asia,
then it spread to the Pacific, though Hawaii, Papua New Guinea and the Solomon
Islands (Wang, 1983). TLB is an aerial pathogen that limits taro production (Brooks,
2008), and is the most destructive Oomycete disease of taro (Fullerton and Tyson,
2003). The symptoms include brown spots and lesions on the leaves reducing the leaf
area and other leaf functions, eventually causing the petioles to collapse (Taylor and
Iosefa, 2013). It was first observed in Samoa, on the Island of Upolu, in the Aleipata
district and rapidly spread all over Samoa, aided by the movement of infected
planting materials from one village to another (Hunter et al., 1998). Prior to the TLB,
Samoan farmers cultivated traditional taro cultivars such as Niue, Manua, Paepae.
Pute Mu, Pula and Sasauli (Liyanage and Misipati, 1993).
3
The total area covered by taro was 16, 000 hectares in 1989, but after the TLB
outbreak, only 4,700 hectares was under taro cultivation by 1999(McGregor et al.,
2011b). A year before the blight outbreak, in 1992, 180,191 kg of taro were sent to
the local market, and a year later, following the TLB, supply fell sharply by 70% to
54,212Kg (Hunter et al., 1998). Taro export was also severely affected by TLB, with
earnings in 1994 declining by 99% (Brunt et al., 2001). The impact of TLB in Samoa
was catastrophic because of the sole dependence of farmers on the Niue taro cultivar
which was the main choice for commercial production. The Niue cultivar covered at
least 90% of taro plantations and during the blight outbreak in 1993 almost all the
farms were destroyed within the first few months (Singh et al., 2010).
Some of the early management practices to control TLB involved the application of
fungicides such as Ridomil MZ and Manzate as well as strict quarantine on the
movement of infected planting materials (Brunt et al., 2001). In addition, cultural
practices such as removing infected leaves, delaying planting and wider planting
space were also encouraged (Hunter et al., 1998). Overall, the chemical and cultural
managements practices mentioned above were expensive but ineffective (Brunt et
al., 2001). Fortunately, the development of new TLB resistant taro varieties through
breeding, provided an alternative method to combat TLB and increase production
(Quero-García et al., 2006). Molecular studies revealed two distinct gene pools in the
Pacific and Asia, opening the possibility for breeding Pacific and Asian taro cultivars
resistant to TLB(Iosefa et al., 2012).
During the first stage of the breeding programme in 1994, exotic taro cultivars from
the Federated State of Micronesia (FSM) were evaluated for their resistance against
TLB. The programme was supported with funding from the European Union-funded
Pacific Regional Agricultural Programme (PRAP) (Iosefa et al., 2012). Two years
later the taro breeding programme for TLB resistance was established at the Alafua
Campus of the University of the South Pacific with funding from Australia (Taylor
and Iosefa, 2013). The PSB-G2, Pwetepwet, Pastora and Toantal cultivars which
showed moderate resistance against TLB, were the first ones distributed to farmers in
1998 (Hunter et al., 1998). The breeding programme received further assistance from
regional and international organisations such as the TaroGen from Australia,
CePaCT, a section of the Secretariat of the Pacific Community, and TANSAO from
South East Asia and Oceania (Taylor and Iosefa, 2013).
4
From 1996 to 2009 and seven breeding cycles later (Table 1); two new taro varieties
(Samoa 1 and Samoa 2) from cycle five had been tested for acceptance in the export
market. The first trial shipment of taro from Samoa was sent to New Zealand in 2010
(Iosefa et al., 2012; MAF, 2015; McGregor et al., 2011b). More recently, export to
America had commenced with two taro consignments being prepared at the Ministry
of Agriculture centre at Nuu (MAF, 2015; Samoa_Observer, 2013). The re-
establishment of export markets to New Zealand, Australia and USA had been a long
in waiting for the suffering taro farmers in Samoa.
Table 1: “Samoa’s taro breeding programme through the TIP (Iosefa et al., 2012)”
Breeding
Cycles
Year No. of
parental
combinations.
No. of
seedling
evaluated.
Top
selections.
1 1996 4 2000 10
2 1998 5 2000 26
3 2000 26 2000 30
4 2002 45 5000 30
5 2005 30 5000 42
6 2007 42 11000 40
7 2009 53 12000 25
Since 2010, taro exports have increased steadily with at least 2, 000 tonnes exported
to New Zealand and USA valued at approximately SAT10 million (MAF, 2015).
There are encouraging signs showed by the two new taro varieties (Samoa 1 and
Samoa 2) as export commodities, and further research is needed, especially on the
physiological characteristics of these two varieties.
1. 2 Objectives
The final yield of most crops is affected by physiological factors operating at
different stages of growth (Sivan, 1976). Also, growth and development studies are
directly related to determining the yields as well as the modification and
improvements of crops yields (De la Pena and Plucknett, 1972). Therefore, growth
5
and development patterns of taro is a prerequisite for understanding physiological
factors controlling yield (Sivan, 1976). In addition, the accumulation and partitioning
of dry matter is essential for determining crop productivity and providing valuable
information for future breeding programmes as well as enhancing root crop yield
(Lahai and Ekanayake, 2009).
Therefore the main objectives of this research are:
1. To characterize the growth and development of taro cultivars, Samoa 1 and
Samoa 2 by determining their dry matter accumulation and partitioning.
2. To determine the response of cultivars Samoa 1 and Samoa 2 to three
different rates of nitrogen (0, 100 and 200 kg ha-1).
The outcomes will provide information to taro breeders for improving productivity.
It will also provide information to support farmers on efficiently applying nitrogen
fertilizers given the projected decline in soil fertility throughout Samoa in the future
(Wright, 1963).
The study was conducted in two parts. Firstly, a preliminary study was established in
pots to determine the response of Samoa 1 and Samoa 2 to five different rates of
nitrogen (0, 50, 100, 150, and 200 kg ha-1). Secondly, the main experiment (field)
was designed to determine the dry matter accumulation and partitioning of Samoa 1
and Samoa 2 as well as their response to three different rates of nitrogen (0, 100, 200
kg ha-1).
6
CHAPTER 2
2.0 Literature Review
2.1 Background to Samoa Samoa consists of four volcanic islands and a series of islets lying between 13° and
15° south latitude and 171 to 173° west longitude with a total land area of 284,000 ha
(FAO, 2003). The two main islands, Upolu and Savaii, are composed of a mass of
successive olivine basalt flows as a result of sub-aerial erosion of two major lava
domes. The highest point in Samoa, Mountain Silisili in Savaii, is 2200 meters above
sea level. The tropical climate in Samoa is mainly influenced by trade winds from the
south east as well as the north and south easterlies (Asghar et al., 1986). Like other
Pacific Islands, the climate has very little variation in temperature with a moderate
seasonality in rainfall. The wet season starts in November and ends in April, while
the dry season runs from May to October (Atherton, 1994). The mean lowland daily
temperature ranged from 27 0C to 30 0C while the monthly rainfall ranged from 250
to 700 mm (Iosefa et al., 2012).
The total population of Samoa is 195,000 and less than 10% are employed in the
agricultural sector (FAOSTAT, 2014). However, a few decades earlier, agriculture
provided support for two-thirds of the total population and contributed to at least
50% of the total GDP (MAF, 2011; Mercer and Scott, 1958). Currently, only 10% of
the GDP is from the agricultural sector and approximately 18,000 people are earning
income from agriculture (FAOSTAT, 2014; MAF, 2011). Several factors such as
tropical cyclones and the outbreak of taro leaf blight were responsible for the drastic
decline in agricultural production and export over the years (Shankman, 1999). For
the period 1994-2010, the TLB alone had cost 112, 000 tonnes in lost exports valued
at (SAT) 196 million (McGregor et al., 2011b).
2.2 Samoa land use
Approximately 80% of the lands in Samoa falls under traditional ownership, 4% as
private freehold lands and the rest owned by the Government and Church missions
(Asghar et al., 1986; Wright, 1963). At least 80% of the arable land is used to grow
7
crops such as coconut, cocoa, banana and taro (Tuivavalagi et al., 2001). The
traditional farming method of shifting cultivation is widely practiced by Samoan
farmers in which crops are planted in a newly cleared land for 2-3 years and then
fallowed for 8-20 years(Rosecrance et al., 1992).
This practice is deeply embedded in Samoan traditions and also the easiest way to
plant crops with minimal agricultural expenses (Wright, 1963). However, increasing
population and growing demand for agricultural produce from export markets is
driving the change from shifting to plantation agriculture, reduced fallow periods and
intensive agricultural cultivation (FAO, 2003; Watters, 1958).
Aerial photographs taken in 1954, 1987 and 1990 showed the decline in forest cover
as a result of agro-deforestation in Samoan villages (Sesega, 2009; Shankman, 1999).
In fact, the extensive forest clearance was instigated by the taro export industry
which peaked in the 1990s (Paulson, 1994). Surprisingly, the only increase in forest
cover was in 1999 showing a 23% increase from 1990 which coincided with the
collapse of the taro industry since 1993 (Paulson, 1994; Sesega, 2009).
2.3 Samoan soils
Soil provides essential services such as the buffering of hydrological cycles,
providing physical support for plants, disposal of dead organic materials, delivering
of nutrients to plants and regulating elemental cycles (Daily, 1997). Some of the
early scientific studies on Samoan soils were carried out by Hamilton, Grange,
Seelye and Birrell in the 1930s (Asghar et al., 1986; Schroth, 1970; Wright, 1963).
Samoan soils are relatively shallow, stony and bouldery, containing oxide rich
minerals derived from olivine basalt (Asghar et al., 1986). Basalt is very common in
the soil parent material from inlands down to the coast (Seelye et al., 1938). The age
of the parent materials ranged from 300 years old in Savaii to two million years old
in Upolu (Natland, 1980). Additionally, the US Soil Taxonomy Classification
systems classified the majority of Samoan soils as members of the Inceptisol soil
order (Wright, 1963).
Gear and Wood (1959) found soil depth and boulderness to be correlated with
different cycles of volcanic activity and erosion, and discussed the volcanic origins,
geology, hydrology and age of the Samoan Islands. Wright (1963) further classified
8
Samoan soils into ninety soil mapping units based on the composition and age of
volcanic rocks as well as climatic patterns (Wright, 1963). Schroth (1970) also
concluded that the age of parent rock and the amount of rainfall had the greatest
influence on soil formation in Samoa. In terms of soil taxonomy, several researchers
have reported the presence of Inceptisols, Andisols, Entisols, Mollisols, Ultisols and
Oxisols soil orders in Samoa (Asghar et al., 1986; Morrison and Asghar, 1992;
Schroth, 1970; Wright, 1963; Yapa, 1996).
2.4 Soil nutrients
The nutrients in uncultivated or forested areas were initially recycled by litter
decomposition, coarse woody debris, and the biological breakdown of other organic
materials. However, as lands are cleared and continuously cultivated, depleted
nutrients need replenishing from alternative sources such as fertilizers. The recent
rapid expansion of the agriculture sector worldwide has increased nitrogen and
phosphorus inputs from synthetic fertilizers by 6 and 3 folds respectively (Tilman,
1999). Furthermore, nutrient conversion from available to unavailable forms is one
of the main reasons causing the decline in soil fertility. For example, nitrogen
experiences mineralization, assimilation, nitrification, denitrification, fixation and
volatization while phosphorus undergoes dissolution as well as fixation. These two
nutrients are the most influential in terms of crop growth, biological production and
yield (Vitousek and Farrington, 1997). The limited availability of potassium in
Samoan soils is a result of the soils having a low cation exchange capacity, severe
leaching, decreasing organic matter supply and high solubility(Blakemore, 1973).
2.5 Taro growth and development
Lebot (2009) proposed six major growth phases of taro which included, (1) root
formation, (2) shoot development, (3) increase in corm size, (4) rapid dry matter
accumulation in the aerial parts, (5) predominant corm and cormel growth to
maturity stage and finally (6) corm and cormel dormancy (Lebot, 2009). He noted
that the first two phase ended at around 40 DAP followed by the maximum shoots
and roots growth while the corm growth started to increase during the 70 to 120 DAP
period. The fourth stage of growth occurred at 140 DAP, in which taro plants
reached greatest height and the leaf blade and petiole achieved significant dry matter
9
accumulations. Afterwards, the heights started to decline at 175 DAP (fifth stage)
while the corm continued to increase to maturity until 210 DAP, follow by the final
phase (“dormancy stage”) at 280 DAP in which the plant total dry matter declined.
Several factors such as, rainfall, temperature and solar radiation can affect the growth
and development of taro (Goenaga, 1995). The accumulation and distribution of dry
matter within plants are important for determining crop productivity (Sun et al.,
2012). Hence, the growth and development of taro is directly related to the
accumulation of dry matter and the distribution of assimilates to its various parts
(Sivan, 1976). Under optimum nitrogen supply, taro has four distinct growth stages:
early establishment (40 DAP), corm initiation to early enlargement (40-90DAP),
maximum corm enlargement (90-130 DAP) and maturity stage (130-160 DAP)
(Manrique, 1994; Pardales Jr, 1986). In the early growth stages of two taro cultivars
(PR-G 066 and PR-G 068) in the Philippines, vegetative organs acted as sinks for dry
matter with more dry matter allocated to the leaves and petioles in comparison to the
roots and corms. The corms start to receive greater portions of the total dry matter at
around 84DAP until the final harvest at 224 DAP (Pardales Jr, 1986). Similar trends
in dry matter partitioning has been observed in several taro cultivars (Blanca,
Hawaii, Lila, Niue, Qawe ni Urau and Tausala ni Samoa) in Fiji (Goenaga, 1995;
Goenaga, 1996; Goenaga and Chardon, 1995; Sivan, 1976).
The maximum corm weight was achieved, when the LAI was 2.1 (Goenaga, 1995).
The leaf blades and petioles dry matter of the Bun-long cultivar increase during early
growth and peaked at 150 DAP and then declined (Miyasaka et al., 2003). The corm
dry matter increased linearly from 30 to 180 DAP and the total dry matter increased
dramatically between 30 and 150 DAP. The roots dry weights on the other hand,
slowly increased from initial planting date to 180 DAP and then decreased
afterwards (Miyasaka et al., 2003). Similarly, the growth and development of taro
under different plant population and seedbed increased their leaf area index (LAI),
plant height, number of leaves in the early stages of growth (90 DAP). While the
growth of the corms was slow at 30 DAP before rapidly increasing to reach optimum
values at 150 DAP (Tumuhimbise et al., 2009).
10
2.6 Dry matter analysis
Dry matter analysis is widely used to characterize growth and development of
different types of crops in yield improvement studies and evaluating the response of
crops to different biotic and abiotic factors (Rogers et al., 1992). Amosa (1993) also
studied dry matter analysis in taro (cultivar Lehua maoli) in Hawaii as affected by
different levels of shading under mixed cropping systems and reported slowed
growth and development and reduction in total biomass with increasing shade. Lahai
and Ekanayake (2009) used dry matter analysis to determine partitioning of
assimilates among different cultivars of cassava and found allocation of dry matter
was cultivar specific. The difference in the dry matter of several taro cultivars were
also reported by several researchers (Aregheore et al., 2000; Aregheore, 2001; De la
Pena and Plucknett, 1972; Goenaga, 1995; Goenaga, 1996; Goenaga and Chardon,
1995; Hartemink and Johnston, 1998; Iosefa et al., 2004; Sivan, 1976).
Cassava cultivars with high partitioning to the leaves and stems had low storage root
yields while those with high allocation to the storage roots had high yields. The
difference in dry matter accumulation and partitioning among the cultivars could be
explained by their photosynthetic production and surrounding environment (Lahai
and Ekanayake, 2009). The dry matter accumulation of potato, yams and tanier
(Xanthosoma spp) increased linearly over time even though significant leaf dry
matter allocation was being observed during the early growth stages (Goenaga, 1994;
Okoli, 1980; Sun et al., 2012). The dry matter content of crops is an important
charcteristic when choosing cultivars for plant breeding programmes and when
selecting ingredients for food processing. Rice cultivars bred with improved dry
matter accumulation had better yields (Chen et al., 2012; Rukundo et al., 2013).
2.7 Taro response to applied nitrogen
Nitrogen is very important in taro cultivation, because it usually limits the growth of
taro and during the early growth stages of taro, nitrogen requirement is relatively
high (Hartemink et al., 2000; Osorio et al., 2003). Nitrogen is a major component for
protein, nucleic acids and enzymes production (Prasad, 1999). The production of
high biomass in the taro leaves, petioles, roots, corms and suckers also require
sufficient supply of nitrogen (Manrique, 1994).
11
Jacobs (1993) conducted an experiment on four local Samoan taro cultivars (Niue,
Manua, Samoa hybrid and Alafua Sunrise) to determine their response to applied
nitrogen. The study concluded that, as the nitrogen supply increased the leaf area,
leaf number, root surface area, dry weights and nitrogen content of the cultivars all
increased. However, high levels of applied nitrogen increased dry matter partitioning
and nitrogen to the leaf and petiole rather than the corm. In another study in Hawaii
De la Pena and Plucknett (1972) found that with increasing N application rates (0-
1120 kg ha-1); the N content in leaf blades and petioles, and the dry weight of leaf
blades, petioles and corms, all increased for both upland and lowland taro. Similarly,
the effect of three different nitrogen rates (25, 50, 100 kg ha-1) on the Lehua Maoli
and Bun Long taro cultivars recorded best leaf and corm yields at 100kg ha-1(De la
Pena and Melchor, 1984).
The form of nitrogen applied also has an effect on growth and development of taro.
Nitrate and ammonium have opposite effects on the total dry weights of taro whereby
increasing the level of nitrate significantly increased the total dry weight while
higher levels of ammonium decreased the total dry weight of taro (Osorio et al.,
2003). For other crops such as rice, the nitrogen fertilizer application increased leaf
weights, enhanced photosynthetic capacity and promoted carbohydrate
accommodation (Chen et al., 2012). In Papua New Guinea nutrient analysis of the
roots of a local cultivar indicated reductions in the uptake of P, K, Mg and Mn in the
fertilized plots (100:50:100 Kg NPK ha-1) while increased uptake of Mg was seen in
the unfertilized plots at 231 DAP. The significance of the study was that the
application of fertilizer decreased the nutrient allocation to the roots; instead more
nutrients were partitioned to the corms (Hartemink and Johnston, 1998).
The timing of the nitrogen application is vital for the accumulation and partitioning
of dry matter between the vegetative and the storage plant organs (Ankumah et al.,
2003). For example, in potato, early application of nitrogen fertilizer resulted in
increased vegetative and total dry matter rather than the tuber dry matter. Thus split
application of nitrogen fertilizer both at planting and before the tuber bulking stage
improved the dry matter accumulation and partitioning in potato tubers (Sun et al.,
2012).
12
CHAPTER 3
3.0 Pot Experiment
3.1 Introduction
Taro remove large quantities of soil nutrients such as N, P, K, Ca and Mg, however
the amount of nutrients removed from the soil depends on the cultivars (Hartemink
and Johnston, 1998; Iosefa et al., 2004; Miyasaka et al., 2002). Since the selected
taro cultivars, Samoa 1 and Samoa 2 are new taro hybrids from the TIP, the pot
experiment was implemented to determine their responses to five different nitrogen
rates (0, 50, 100, 150, and 200 kg ha-1). Around the world, taro is reported to respond
to different rates of nitrogen from as low as 50 kg ha-1 to 2000 kg ha-1 (De la Pena
and Plucknett, 1972; Gouveia, 1993; Hartemink et al., 2000; Jacobs, 1990; Manrique,
1994; Osorio et al., 2003; Prasad, 1999). These responses by taro cultivar to nitrogen
application are influenced by a variety or combination of biotic (pathogens, types of
cultivars) and abiotic factors such as the environment. Soil fertility plays an
important role in taro production, however environmental parameter such as rainfall,
temperature and solar radiation are also very important. Therefore, trying to control
some of the above-mentioned variables, while only manipulating the rates of
nitrogen was one reason that encouraged the implementation of the pot experiment.
Furthermore, the pot experiment was setup to study the effect of nitrogen on the
growth characteristics of the two new cultivars such as their height and LAI as well
as the number of leaves produced. In accordance with some of the literature
reviewed a split plot layout was used as the experimental design for the pot
experiment (De la Pena and Melchor, 1984; De la Pena and Plucknett, 1972;
Goenaga, 1995; Goenaga, 1996; Goenaga and Chardon, 1995; Tumuhimbise et al.,
2009). In addition to the above-mentioned reasons for setting up the pot experiment,
one of the main purposes of the pot experiment is to act as a preliminary study to the
“main experiment” which is the field study. Therefore, utilizing the five nitrogen
rates in the pot experiment will assist in determining the nitrogen rates for the field
experiment. Reducing the levels of nitrogen rates for the field study will both limit
the unnecessary fertilizer consumption as well as using only the application rates
which have significant responses from the two cultivars. These measures are
13
essential for reducing the study costs so that the experiments will fall within the
allocated budget.
3.2 Materials and Methods
A split plot design was used for the pot experiment with the two cultivars being used
as the main plots and nitrogen rates (0, 50, 100, 150, and 200 kg ha-1) as the sub plots
arranged randomly with four replicates for each treatment. The pots were filled with
10 kg of soil collected from the site of the field trial (Inceptisols) having a pre-plant
soil nitrogen of 0.38% (moderate) and a soil pH of 6.1. Urea containing 46% of
nitrogen was used as the fertilizer at 10.8, 21.7, 32.6, 43.4 g/ pot to attain 50, 100,150
and 200 kg ha-1 N. Please refer to Appendix 1for N rate calculations which contain
calculations for the N rate of the field experiment which is exactly the same as the
calculation used for the pot experiment.
Suckers of Samoa 1 and Samoa 2 from a local farmer were used as planting materials
because ranging 2-3 cm in diameter at the base of the petiole. The cultivars were
planted on June 14 to December 15 2014 and the experiment was kept free from
weeds by hand weeding and was irrigated on a daily basis. Also the average annual
rainfall and temperature at the site is 450 mm and 28 0C respectively (Iosefa et al.,
2012). The numbers of leaves, leaf area index (LAI) and plant height were recorded
fortnightly to study development and growth pattern. The LAI was measured using
the LAI-2200 Plant Canopy Analyser by LI-COR Biosciences. The leaf number and
plant heights were determined by counting the leaves and the meter ruler
respectively.
The plants were harvested six months after planting, washed to remove the soil and
air dried until water completely evaporated. Afterwards, the plants were divided into
leaf blades, petioles, corms, roots and suckers, then, their fresh weights were
recorded and placed in paper bags for drying at 65 0C until constant dry weights were
obtained. The matter content of the leaf blades, petioles, roots, corms and suckers
were then calculated separately, according to the formula:
DM (%) = [(sample dry weight) / (sample fresh weight)] x 100
14
0102030405060708090
0 100 200 50 150 0 100 200 50 150 0 100 200
35 70 105 140 175
Hei
ght (
cm)
DAP
Samoa 1
Samoa 2
N rates; kg ha-1
Data collected were subjected to the standard analysis of variance (ANOVA) of a
split plot design using the GenStat Discovery Edition 4 statistical software. The
comparisons between the treatment means were created using the least significant
difference (LSD) at the 5% significance level.
3.3 Results and Discussions
3.3.1 Growth Measurements
3.3.2 Plant height
Figure 1: “The effect of five nitrogen rates on the heights (cm) of Samoa 1 and Samoa 2.”
The difference in height between the two cultivars is highly significant (P < 0.001),
likewise the nitrogen rates (P < 0.002) and the sampling dates (P < 0.001) are also
highly significant at the 5% probability level (Appendix 3). The interaction between
the taro cultivars and nitrogen rates is also highly significant (P < 0.001). In terms of
the cultivars response to the different rates of nitrogen, Samoa 1 was taller than
Samoa 2 in the majority of nitrogen rates during the six months of growth (Fig. 1).
Heights of the two cultivars increased after initial planting to their tallest values at
140 DAP; for Samoa 1 (73.45 cm) and Samoa 2 (67.35 cm), thereafter their heights
started to decline until harvest at 175 DAP (Fig. 1). The above results are supported
15
by a previous study that compared the performance of traditional taro cultivars in
Samoa. In conclusion, the researcher suggested that heights of several cultivars
peaked very late in the growth stages and then declined afterwards (Cable and
Asghar, 1983). Roger et al (1992) also reported that the Niue cultivar, under different
levels of sunlight exposure and mulching treatments reached peak heights at 150
DAP. Furthermore, Tumuhimbise et al (2009) also proved that the heights of taro
plants increases overtime (150 DAP) irrespective of soil preparation methods and
spacing.
3.3.3 LAI
Figure 2: “The changes in LAI for Samoa 1 and Samoa 2 during six months of growth.”
The difference between the LAIs of the two cultivars is highly significantly different
(P < 0.001) from 35 to 175 DAP. There is also a significant (P < 0.001) difference
between the cultivars LAI at each of the sampling dates. LAI for the two cultivars
peaked at 105 DAP in which Samoa 1 and Samoa 2 reached LAI of 1.5 and 1.8
respectively (Fig 2). Overall, the LAIs for Samoa 1 and Samoa 2 showed a similar
trend in terms of their responses to the different rates of nitrogen with Samoa 2
having a higher LAI than Samoa 1 in all of the different nitrogen rates except for the
200 kg ha-1 rate at 70 and 175 DAP (Fig 7). Similar results were reported by Prasad
0
0.5
1
1.5
2
2.5
35 70 105 140 175
LAI
DAP
Samoa 1Samoa 2
16
0
1
2
3
4
5
6
7
0 100 200 50 150 0 100 200 50 150 0 100 200
35 70 105 140 175
Num
ber o
f lea
ves
DAP
Samoa1
N rates; kg
(1999) who discussed the influence of applied nitrogen to the LAI of taro. He
concluded that the LAI of the Vula Ono taro cultivar increased from 1.8 at 0 kg ha-1
to 2.3 after applying 100 kg ha-1 of nitrogen. Likewise, the Tausala ni Samoa cultivar
had LAI of 1.2 and 1.9 at 0 and 100 kg ha-1 of nitrogen. Therefore, increasing the
nitrogen rates from 0 to 100 kg ha-1 increased the LAIs of the Tausala ni Samoa and
Vula Ono cultivars in Fiji. Similarly, the Niue, Lehua, Blanca and Lila cultivars
reached maximum LAIs ranging from 1 to 1.8 at 110DAP for an experiment in
Puerto Rico (Goenaga, 1996). But, under rainfed conditions the Bun Long cultivar in
Hawaii reached a maximum LAIs of 3.0 at 10 months after planting (Miyasaka et al.,
2003).
3.3.4 Development measurement
3.3.5 Number of leaves
Figure 3: “The effect of five nitrogen rates on the number of leaves of Samoa 1 and Samoa 2.”
17
The difference in the number of leaves between the two cultivars is highly significant
(P < 0.001), likewise the nitrogen rates (P < 0.033) and the sampling dates (P <
0.001) are also highly significant at the 5% probability level. The interaction between
the taro cultivars and the five harvest dates is also highly significant (P < 0.006).The
number of leaves for the two cultivars increased during growth until 140 DAP where
Samoa 1 decreased from 4 to 3 while Samoa 2 declined from 6 to 5 at 175 DAP. In
Fiji, Prasad (1999) suggested that the number of leaves for the Vula Ono cultivar
decreased as more nitrogen was applied while the Tausala ni Samoa cultivar had
more leaves at 200 than 100 Kg ha-1. Tumuhimbise et al (2009) also concluded that
the number of leaves for taro cultivars in Uganda increased from initial planting date
to 90 DAP in which the cultivar reached a maximum of six leaves. As such, the
above results are in accordance with other studies from different regions of the
world.
3.3.6 Dry matter accumulation (175 DAP)
3.3.7 Leaf blades and petioles dry matter
Figure 4: “The effect of five nitrogen rates on the LDM and PDM of Samoa 1 and
Samoa 2.”
0.00
10.00
20.00
30.00
0 50 100 150 200
DM
, g/p
lant
Leaf blades Samoa 1Samoa 2
0.00
20.00
40.00
60.00
0 50 100 150 200
Petioles
N rate, kg ha-1
18
The difference between the leaf blades and petioles dry matters of Samoa 1 and
Samoa 2 are highly significant (P < 0.001). Likewise, the difference between the two
cultivars LDM and PDM as a result of the five rate of nitrogen were highly
significant (P <0.001). The interaction between the taro cultivars and the nitrogen
rates is also highly significant (P < 0.001) for both the LDM and PDM of Samoa 1
and Samoa 2.There were sharp increases for the LDM (17.2g/plant) and PDM (33.2
g/plant) of Samoa 2 at 50 kg ha-1. Samoa 1 on the other hand had its highest LDM
and PDM at 50 and 150 kg ha-1 respectively. The above results had supported
suggestions by (Hartemink et al., 2000) that applying 100 and 200 kg ha-1 of
nitrogen fertilizer increases the above-ground biomass of taro by 16.5% and 28.3%
respectively. De la Pena (1984) also produced similar results whereby increasing the
rate of nitrogen to 100 kg ha-1 enhanced the vegetative yield of the Lehua Maoli and
Bun Long taro cultivars.
3.3.8 Corm and roots dry matter
Figure 5: “The effect of five nitrogen rates on the CDM and RDM of Samoa 1 and Samoa 2.”
0.00
50.00
100.00
150.00
0 50 100 150 200
DM
, g/p
lant
Corm Samoa 1Samoa 2
0.00
5.00
10.00
15.00
0 50 100 150 200
Roots
N rate, kg ha-1
19
The difference between the CDM and RDM of Samoa 1 and Samoa 2 are highly
significant (P < 0.001). Likewise, the difference between the two cultivars CDM and
RDM as a result of the five rate of nitrogen were highly significant (P <0.001). The
interaction between the taro cultivars and the nitrogen rates is also highly significant
(P < 0.001) for both the CDM and RDM of Samoa 1 and Samoa 2. Samoa 1 had
more CDM at 50 kg ha-1 (67.4 g/plant) than any of the other nitrogen rates. Likewise,
the CDM of Samoa 2 peaked at 50 kg ha-1 (112.34). Meanwhile, the RDM of Samoa
2 was higher than Samoa 1 at all of the five nitrogen rates. The above results are in
accordance with those by (Hartemink et al., 2000) in which improved rates of
nitrogen fertilizers (0 to 200 kg ha-1) increases the “marketable yield” (corm) of taro
from 5.8 Mg (Megagram) ha-1 to 6.4 Mg ha-1. Likewise, Manrique (1994) reported
that raising the nitrogen level from 40 to 80 kg ha-1 had lead to a 25% increase in the
corm yield.
3.3.9 Suckers and Total dry matter
Figure 6: “The effect of five nitrogen rates on the SDM and TDM of Samoa 1 and Samoa 2.”
-5.000.005.00
10.0015.0020.00
0 50 100 150 200DM
, g/p
lant
Suckers Samoa 1Samoa 2
0.00
100.00
200.00
300.00
0 50 100 150 200
Total
N rate, kg ha-1
20
The difference between the SDM and TDM of Samoa 1 and Samoa 2 are highly
significant (P < 0.001). Likewise, the difference between the two cultivars CDM and
RDM as a result of the five rate of nitrogen were highly significant (P <0.001). The
interaction between the taro cultivars and the nitrogen rates is also highly significant
(P < 0.001) for both the SDM and TDM of Samoa 1 and Samoa 2. Samoa 1
responded consistently to the applied nitrogen when it produced suckers at all of the
five different nitrogen rates while Samoa 2 was unable to produce any suckers at 100
kg ha-1 of nitrogen. The TDM of two taro cultivars in Hawaii revealed that the TDM
of upland and lowland taro increased when the rate of nitrogen was doubled (De la
Pena and Plucknett, 1972).
3.4 Conclusion
The main reason for carrying out the pot experiment was to provide further support
for the nitrogen rates determined from the literature review and also to have prior
understanding on some of the physiological characteristics of Samoa 1 and Samoa 2.
Such as the leaf area index, plant height and the number of leaves that will be further
explored and analyzed in the field trial. Therefore, from the pot trial it was found that
Samoa 1 performed better than Samoa 2 in terms of plant height during six months of
growth. However, Samoa 2 had a higher leaf area index than Samoa 1, which, to an
extent, makes sense since Samoa 2 also had more leaves than Samoa 1 at each of
monthly reading regardless of the nitrogen rates.
The other reason for conducting the pot experiment was to setup a baseline for the
data comparison with the field trial later on. The pot experiment results indicated that
for the leaf blades and petioles dry matter, Samoa 2 responded well to 50 and 150 kg
ha-1. The CDM of Samoa 1 increased when the rate of nitrogen was raised to 50 kg
ha-1 and then declined again at 100 and 150 kg ha-1 before increasing again at 200 kg
ha-1. The CDM of Samoa 2 however, only improved at 50 kg ha-1 and gradually
declined as the rate increased from 100 to 200 kg ha-1. The RDM of the two cultivars
peaked at 50 and 150 kg ha-1 for Samoa 1 and Samoa 2 respectively. All in all, the
differences between the LDM, PDM, CDM, RDM, SDM and TDM of Samoa 1 and
21
Samoa 2 as a result of the five rates of nitrogen were all significant at the 5%
probability level.
Therefore, as means of meeting the objectives of this study the 0, 100, 200 kg ha-1
will be used for the main experiment (field trial). As shown from the results above,
the other nitrogen rates increased the leaf blades, petioles and roots dry matters.
Furthermore, as shown from the literature review (De la Pena, 1967; De la Pena and
Plucknett, 1972; Hartemink et al., 2000; Jacobs and Clarke, 1993; Prasad, 1999) the
three rates above had produced promising results in terms of improving yield in
previous experiments.
22
CHAPTER 4
4.0 Field Experiment
4.1 Introduction
Nitrogen is one of the most influential nutrient in terms of crop growth, biological
production and yield (Vitousek and Farrington, 1997). It is often the most limiting
mineral nutrient for taro growth, nitrogen deficient taro plants have stunted roots,
yellowing of the leaf blades, premature death of older leaves, and lower yields
(Miyasaka et al., 2002; Osorio et al., 2003). The field experiment was established to
address the growth and development of the blight resistant taro cultivars from the
TIP as well as finding ways to cope with the highly weathered and the projected
decline in soil fertility of Samoan soils. Generally the field experiment was used to
determine the growth and development of the Samoa 1 and Samoa 2 taro cultivars,
however different rates of nitrogen applied as urea were implemented to determine
the responses of the new hybrids to nitrogen. After years of carrying out experiments
on aroids in the Pacific, Lebot postulated that taro has six growth stages, however
under optimum nitrogen supply the growth stages are reduced to four with the corm
reaching maturity relatively early (Lebot, 2009; Manrique, 1994).
Therefore, three nitrogen rates (0, 100, and 200 kg ha-1) were used in the field
experiment, which were decided from the preliminary pot experiment as well as the
literature reviewed. The positive responses of taro such yield improvements around
the world to different rates of nitrogen ranged from 50 kg ha-1 to 2000 kg ha-1 (De la
Pena and Plucknett, 1972; Gouveia, 1993; Hartemink et al., 2000; Jacobs, 1990;
Manrique, 1994; Osorio et al., 2003; Prasad, 1999). These wide varieties of
responses are mainly attributed to several factors such as plant nutrition, rainfall and
temperature which have strong implications on the plants photosynthetic capacity.
The site for planting taro can be either lowland (paddy environment) or upland
depending on the conditions in which taro is grown also influenced the amount of
nitrogen necessary for producing marketable corm yields. Specifically, this study
focussed on upland taro which is known to increase dry matter partitioning to the
corms under optimum nitrogen supply (Manrique, 1994). Due to the literature
reviewed and the factors (cultivars, nitrogen rates and number of harvest dates)
23
evaluated, the field experiment was setup in a split split plot design (De la Pena and
Melchor, 1984; De la Pena and Plucknett, 1972; Goenaga, 1995; Goenaga, 1996;
Goenaga and Chardon, 1995; Tumuhimbise et al., 2009).
4.2 Materials and Methods
The experiment was carried out at the USP Samoa, Alafua Campus (13 51oS 171
47oW). The soil is a well drained Inceptisol (very fine, halloysitic, isohyperthermic
family of the Fluventic-Oxic Dystropepts), specifically classified as the Alafua soil
series (Schroth, 1970).
The pre-plant soil nitrogen was 0.38% (medium level, according to Blakemore
(1981)) and the average soil pH was 6.1 at the 0-15 cm soil depth. The mean lowland
daily temperature ranged from 27 0C to 30 0C while the monthly rainfall ranged from
250 to 700 mm and the site was previously used by IRETA (Institute for Research,
Extension and Training in Agriculture) for planting taro during the past decades
(Iosefa et al., 2012).
Taro suckers of cultivars Samoa 1 and Samoa 2 from a local farmer were planted in
the field from January 16, 2015 to July 16, 2015. The planting materials were
randomly arranged in a split-split plot design replicated three times. Each replication
contained two main plots (cultivars) which were split into three nitrogen rates (0,
100, 200 kg ha-1), and then split again to accommodate five dates of harvest
(Appendix 2).
Planting sticks traditionally used in Samoa for planting taro were also used in the
experiment to produce planting holes of 20 cm deep and 10 cm wide to plant taro
tops of Samoa 1 and Samoa 2 in the field. There was no irrigation during the six
months of the experiment, only relying on rainfall in the study area for water supply.
Each subplot contained 16 plants spaced 1 x 1 meter apart; the inner 4 plants were
sampled for dry matter analysis. The experimental plants were surrounded by guard
plants between each subplot. The three nitrogen rates (0, 100, 200 kg ha-1) were
applied (split application) to each plant during the first month of planting in which
the nitrogen was applied as urea (46% nitrogen). Since the nitrogen was applied on a
24
split application basis, the 21.7 g of urea used per plant for the 100 kg ha-1 was
divided by three to get 7.2 g which was used for the three split applications during
the fourth and fifth week of January and the last application was on the first week of
February. The same procedure was also used when applying the 200 kg ha-1 rate.
Because of the positive responses of the two cultivars to nitrogen application in the
pot experiment, it was agreed that nitrogen (addition of other nutrients like P and K
were not considered) is the main limiting nutrient for this specific study area. In
terms of maintenance, the experiment was kept free from weeds throughout by hand
weeding and by spraying with the Gramoxone herbicide.
Plants were harvested for dry matter analysis at 35, 70, 105, 140 and 175 DAP. At
each harvest, a spade was used to dig out the plants and recover as many broken
roots as possible. Plants were then washed with water to remove the soil and then air
dried until water had completely evaporated. Afterwards, the plants were divided into
leaf blades, petioles, corms, roots and suckers (whole plant), then, their fresh weights
were recorded and placed in paper bags ready for drying.
During the early stages of the experiment the dry weights were determined directly
from the entire bulk fresh weights. However, as the size of the petioles, corms and
suckers increased in the later harvests, it was necessary to take subsamples of these
plant parts for dry matter determination. Subsamples were taken and their fresh
weights recorded before drying to constant weights and recorded as subsample dry
weights. Finally, the dry weight of the sample was calculated according to the
following formula:
Sample Dry Wt = Sample Fresh Wt x [(Subsample Dry Wt) / (Subsample
Fresh Wt)]
The samples of the different taro organs were dried at 65 0C until constant dry
weights were accomplished. Percentage dry matter content (%) was calculated as the
ratio of dry weights/ fresh weights x 100% for the leaf blades, petioles, roots, corms
and suckers. Dry matter partitioning was calculated as the ratio of the dry matter of
individual plant parts to the total plant dry matter. For example, the dry matter
partitioned to the leaf blades is the ratio of leaf blades dry matter to the total plant dry
matter etc.
25
050
100150200250300350
Jan1
-7
Jan1
…
Jan2
…
Feb1
…
Feb2
…
Mar
1…
Mar
2…
Apr
9…
Apr
2…
May
…
May
…
Jun4
-10
Jun1
…
Jul2
-8
Jul1
6…
Jul3
0…
Aug
1…
Rai
nfal
l (m
m)
Weeks
Weekly rainfall in the first 8 months of 2015 at project site, Alafua Campus .
Additionally, growth measurements such as the plant height and leaf area index
(LAI) as well as development measurements such as the number of leaves and
suckers were all collected on a fortnightly basis to provide further understanding on
the growth and development of Samoa 1 and Samoa 2. The plant height which was
defined as the distance from ground level to the highest leaf blade was measured
using a meter ruler. The LAI was measured using the LAI-2200 Plant Canopy
Analyser by LI-COR Biosciences. Leaf and sucker numbers were counted and
recorded during these fortnightly measurements on the same plant during the six
months of the study.
Rainfall data were collected using the WatchDog 2000 Series weather station from
Spectrum Technologies, Inc (Illinois, USA). The weather station was installed near
the field trial after all the taro plants were planted at the end of January 2015. Data
collected were subjected to the standard analysis of variance (ANOVA) of a split-
split plot design using the GenStat Discovery Edition 4 statistical software. The
comparisons between the treatment means were created using the least significant
difference (LSD) at the 5% probability level (P values <0.05).
4.3 Results and Discussions
4.3.1 Monthly rainfall during field experiment
Figure 7: “Weekly rainfall recordings at the project site for the eight months from
January- August 2015.”
26
020406080
100120140
0 100 200 0 100 200 0 100 200 0 100 200 0 100 200
35 70 105 140 175
Hei
ght (
cm)
DAP
Samoa 1Samoa 2
N rates; kg ha-1
The weekly rainfall recorded at project site shows wet conditions in the first 3
months of the year with the highest weekly rainfall recorded in week 5 (end of Jan to
beginning of Feb). The high humid conditions in the early months of the year
coincide with the wet seasonal months. Most of the weeks registered rainfall above
50mm with generally less rainfall in July and August when drier than normal rainfall
conditions set in. The second highest weekly rainfall was recorded in the second
week of May. The subsequent 2 weeks also experienced fairly good rainfall brining
much needed rain to the Alafua area. The high rainfall conditions in the first 4
months of the year positively impacted on the taro growth and are also thought to
have influenced treatment effects and cultivar responses in this research.
4.3.2 Growth Measurements
4.3.3 Plant Height
Figure 8: “The effect of three nitrogen rates and five harvest dates on the heights (cm) of Samoa 1 and Samoa 2.”
The differences between the heights of Samoa 1 and Samoa 2 as a result of the three
rates of nitrogen (P = 0.04) and the five harvest dates (P < 0.001) are significant
(Appendix 4). The interaction between the nitrogen rates and harvest dates is highly
significant (P < 0.001). The heights increased from 35 DAP and peaked at 140 DAP
at 100 kg ha-1 of nitrogen for both cultivars which ranged from 40-115 cm for
Samoa 1 and 58-114 cm for Samoa 2 (Appendix 5). Afterwards, the heights of the
27
00.5
1
1.5
22.5
3
3.5
35 70 105 140 175
LAI
DAP
Samoa 1Samoa 2
two cultivars started to decline, with Samoa 1 dropping from 94 to 89.2 cm, while
the height of Samoa 2 was reduced from 100 to 97.2 cm. Previous work on a local
taro cultivar (Niue) in Samoa supported the above results in which the taro heights at
30 DAP was 60 cm while at 60 DAP the heights reached 82 cm and continued to
increase until 120 DAP whereby the heights started to decline (Rogers et al., 1992).
Furthermore, Amosa (1993) found that taro plant heights at 40 and 80 DAP were
approximately 50 and 90cm respectively in a study conducted in Hawaii. Likewise,
Tumuhimbise et al (2009) also found similar taro heights at 30, 60, and 90 DAP in
which the taro heights were 65, 75 and 90 cm respectively in Uganda. Therefore, the
heights achieved by Samoa 1 and Samoa 2 are in accordance with the heights
reported by other researchers mentioned above. However in this study maximum
heights at all rates of nitrogen were achieved at 140 DAP which is a bit late
compared to other studies (Amosa, 1993; Rogers et al., 1992). This would suggest
that the vegetative growth of the crop was extended in this study and it is thought
that high rainfall experienced during the first four months of the growing season
(January to May) is responsible for this extended vegetative growth. The maximum
heights for Samoa 1 and Samoa 2 in the pot experiment were recorded at 105 DAP.
4.3.4 Leaf Area Index (LAI)
Figure 9: “The effect five harvest dates on the LAIs of Samoa 1 and Samoa 2.”
28
0
5
10
15
35 70 105 140 175
Leav
es
DAP
Samoa 1Samoa 2
There are significant differences in LAI between the cultivars (P = 0.003) and
between harvest dates (P < 0.001). However there is no significant difference with
respect to the influence of the applied nitrogen on the LAIs of the two cultivars. The
LAI for Samoa 1 and Samoa 2 increased from 35 to 140 DAP where they obtained
maximum LAIs of 2.15 at the 0 kg ha-1 and 2.93at the 100 kg ha-1 N respectively.
The highest LAIs were attained at the same time when the cultivars were at their
maximum heights. Sivan (1976) provided similar results when he measured the
maximum LAIs for Tausala ni Samoa (2) and Qaweni Urau (3) taro cultivars at 119
DAP. Further support for the attainment of maximum LAI at midway through the
growing season was put forward by Amosa (1993) where he found that the Lehua
cultivar in Hawaii reached a maximum LAI of 1.6 at 150 DAP. Miyasaka (2003) also
reported that the LAI for the Bun Long cultivar in Hawaii reached a maximum LAI
of 3 as it approached maturity. Likewise, the maximum LAIs for the Blanca (2.0) and
Lila (2.1) cultivars were both recorded at 145DAP (Goenaga, 1995). Hence as stated
by (Amosa, 1993; Goenaga, 1995; Sivan, 1976) and from the results above, the
maximum LAI of taro is expected somewhere between 120 and 150 DAP. In
contrast, the maximum LAI of Samoa 1 and Samoa 2 in the pot experiment were
both recorded at 105 DAP. It is believed that the plant growth in the pot experiment
may have been restricted due to growing conditions.
4.3.5 Development measurement
4.3.6 Leaf number
Figure 10: “The effect of five harvest dates on the number of leaves of Samoa 1 and Samoa 2.”
29
The difference in the number of leaves between the cultivars at the five harvest dates
is highly significant (P < 0.001), Also, the difference in the number of leaves
between Samoa 1 and Samoa 2 is significantly different (P = 0.005). The interactions
between the nitrogen rates and harvest dates (P = 0.004) as well between the cultivars
and harvest dates (P < 0.001) are also significant. The numbers of leaves for the two
cultivars increased during the growing season from 35 to 175 DAP. For example, the
number of leaves of Samoa 1 accumulated up to10 while Samoa 2 increased its
leaves to reach 13 after six months of growth and development. Despite that, the
number of leaves for Samoa 1 increased from 6 to 7 when the rate of nitrogen was
raised to 100 kg ha-1 but the application of 200 Kg ha-1did not change the number of
leaves which still remained at 6. The above results are also supported by Cable and
Asghar (1983) after comparing the performance of six traditional Samoan taro
cultivars. The two researchers concluded that the Faeleele cultivar increased its
leaves production from 0 at the initial planting date to 7 after six months of planting.
Amosa (1993) also found similar results where the number of leaves at 140 DAP was
13 while Tumuhimbise et al (2009) recorded a 50 % rise in leaf numbers after 30
days of planting.
4.3.7 Sucker Production
Figure 11: “The effect of five harvest dates on the number of suckers of Samoa 1 and Samoa 2.”
-5
0
5
10
15
20
70 105 140 175
Suck
ers
DAP
Samoa 1Samoa 2
30
The number of suckers produced between each of the five harvest dates is highly
significant (P < 0.001). Sucker production started at 70DAP for both Samoa 1 and
Samoa 2 and the number of suckers rapidly accumulated from 70 to 140 DAP until
175 DAP where a gradual decline was observed. The above results are supported by
Sivan (1976) who concluded that suckers only emerged from the mother plants at 65
DAP and continued to accumulate until the final harvest. The Hawaii, Tausala ni
Samoa and Qawe ni Urau cultivars had 9, 3 and 4 suckers respectively during
harvest. Meanwhile, (Cable and Asghar, 1983) found that traditional Samoan taro
cultivars such as Niue, Paepae, Tusitusi and Pula all increased sucker production
during the seven months of growth and development. In Fiji, Prasad (1999) reported
that Tausala ni Samoa increased its suckers from 1 to 3 while Vula Ono showed a
60% jump in sucker production after the application of higher levels of nitrogen.
4.3.8 Dry matter accumulation
4.3.9 Leaf blade (LDM)
Figure 12: “The effect of five harvest dates on the LDM of Samoa 1 and Samoa 2.”
There is a significant difference (P < 0.001) between the two cultivars LDM
accumulation at the five harvest dates but the influence of the nitrogen rates was not
significant. This supported the fact that LDM received large portion of the total dry
matter early in the growth stages but started to decrease as the taro plants moved
-10
0
10
20
30
40
50
60
35 70 105 140 175
Dry
mat
ter (
g/pl
ant)
DAP
Samoa 1Samoa 2
31
towards maturity. The drop in the leaf blade dry matter for both cultivars at 175 DAP
coincided with the declining LAI in Fig 9. With regards to the three rates of nitrogen,
Samoa 1 at 35 DAP increased its LDM with the improved nitrogen supply while at
70 DAP a slight increase was recorded from 0 to 100 and then declined again at 200
Kg ha-1. The leaf blades dry matter for Samoa 2 at 35 DAP increased as the nitrogen
rate was raised from 0 to 100 kg ha-1 but declined when the nitrogen rate was further
increased to 200 Kg ha-1. A very sharp increase was observed at 70 DAP for the 0
and 100 kg ha-1 of nitrogen applied. The LDM for Samoa 2 continued to increase at
105 and 140 DAP regardless of the amount nitrogen added. The above results is
supported by Sivan (1976) who showed that for the three cultivars he studied, their
LDM increased from planting until 140 DAP even though the magnitude of leaf
blades dry matter differed among cultivars. He concluded that the difference in leaf
blades dry matter between the cultivars was due to their difference in leaf angles and
leaf areas affecting sunlight absorption and photosynthesis. Rogers et al (1992) also
reported that the leaf area of the Niue cultivar peaked at 150 DAP and then declined
afterwards.
4.4.0 Petiole (PDM)
Figure 13: “The effect of five harvest dates on the PDM of Samoa 1 and Samoa 2.”
-40-20
020406080
100120140160
35 70 105 140 175
Dry
mat
ter (
g/pl
ant)
DAP
Samoa 1Samoa 2
32
-500
50100150200250300
35 70 105 140 175
Dry
mat
ter (
g/pl
ant)
DAP
Samoa 1Samoa 2
There is a significant difference between the two cultivars PDM accumulation at the
five harvest dates (P < 0.001) but the influence of the nitrogen rates was not
significant. The PDM of Samoa 1 accumulated over time from 4.8 to 94.95 g/plant
during the 35 to 140 DAP time period while the petioles dry matter for Samoa 2 also
increased from 6.8 to 119.9 g/plant at 35 to 140 DAP. Afterwards, both cultivars lost
petioles dry matter in the final harvest at 175 DAP. Overall, Samoa 2 (69.5 g/plant)
had a larger PDM than Samoa 1 (51.75 g/plant) at the final harvest. Samoa 1 and
Samoa 2 increased their petioles dry matters at 70 DAP as the rate of nitrogen was
raised from 0 to 200 Kg ha-1. At 105 DAP, Samoa 1 experienced enhanced PDM as
the nitrogen rate increased from 0 (65.25 g/plant) to 100 kg ha-1 (72.25 g/plant) and
declined at 200 kg ha-1 (70.75 g/plant). The PDM for Samoa 2 on the other hand
spiked at 100 kg ha-1 (162 g/plant) from 58.25 g/plant at 0 kg ha-1 and then dropped
at 200 kg ha-1 (134 g/plant). In the final harvest (175 DAP) both Samoa 1 and
Samoa 2 had reductions in their total petioles dry matters from the previous harvest
at 140 DAP. The observations above closely resembled the results of petioles dry
matter by Sivan (1976) and Goenaga (1995) where the PDM increased from planting
(6.5 g/plant) to 140 DAP (95 g/plant) and 50 (5 g/plant) to 115 DAP (32 g/plant)
respectively before their PDM accumulations declined. The difference in the
magnitude of petiole dry matter between the cultivars was due to the ability of
certain cultivars to intercept more sunlight than the others (Amosa, 1993; Goenaga,
1995; Sivan, 1976).
4.4.1 Corm (CDM)
Figure 14: “The effect of five harvest dates on the CDM of Samoa 1 and Samoa 2.”
33
The difference between the CDM of Samoa 1 and Samoa 2 at each harvest dates is
highly significant (P < 0.001) but the effect of the three N rates was not significant.
Corms dry matters (CDM) of both Samoa 1 and Samoa 2 increased over time from
35 DAP (5.8 and 4.6g/plant) to 175 DAP (138.5 and 202.1 g/plant) respectively. The
CDM of Samoa 2 cultivar was higher than Samoa 1 at 70,105,140 and 175 DAP.
During the early growth stages (35 to 105 DAP), there was a gradual increase in
CDM for Samoa 1 and Samoa 2 in response to the nitrogen applied. However at 140
DAP the CDM of Samoa 1 increased from 46.75 to 68.25 g/plant after the addition of
100 kg ha-1 and declined to 61.75 g/plant at 200 Kg ha-1. Samoa 2 also experienced
the same trend in Samoa 1 where the CDM increased from the 0 to 100 kg ha-1 and
also declined at 200 Kg ha-1. Furthermore, at 70 DAP both cultivars continued to
increase CDM irrespective of the nitrogen applied. The above results are supported
by Sivan (1976) where the CDM for the Hawaii cultivar increased from 5g/plant at
35 DAP to 155 g/plant at 290 DAP. While the CDM of the Tausala ni Samoa cultivar
increased from 5 g/plant to 170 g/plant during the same period. Goenaga (1995) also
reported that corm dry matter increased from 50 DAP (7g/plant) to 300 DAP (165
g/plant) for the Blanca cultivar. Moreover, Amosa (1993) reported that the CDM
accumulation for the Lehua Maoli cultivar increased from 40 to 235DAP. Likewise,
similar varieties of taro in the Philippines showed enhanced corm dry matter from
planting until 224 DAP (Pardales Jr, 1986). Overall, even though the same trend was
observed, the CDM between the cultivars was different from each other as a result of
their sunlight absorption and photosynthetic capacity (Amosa, 1993; Goenaga, 1995;
Pardales Jr, 1986; Sivan, 1976).
34
4.4.2 Root (RDM)
Figure 15: “The effect five harvest dates on the RDM of Samoa 1 and Samoa 2.”
The difference between the RDM of the two cultivars at each of the five harvest
dates is highly significant (P < 0.001) while the difference as a result of the three
nitrogen rates is not statistically significant. The interaction between the cultivars and
the five harvest dates is also highly significant (P < 0.001). The roots dry matter
(RDM) for Samoa 1 increased from 35 (0.56 g/plant) to 140 DAP (9.46 g/plant)
before declining at 175 DAP (3.14). Likewise, Samoa 2 also experienced rapid RDM
accumulations from initial planting to 140 DAP. Overall, the RDM of Samoa 2 (8.81
g/plant) was higher than Samoa 1 (4.5 g/plant). Limited RDM was recorded at 35
DAP, but started to increase rapidly from 70 to 105 DAP for both Samoa 1 and
Samoa 2. This was followed by rapid increase in the RDM for Samoa 2 (9.5 to 23.6
g/plant) and Samoa 1 (from 5.3 to 9.5 g/plant) at 140 DAP. Afterwards, there were
huge drops in the RDM of Samoa 1 and Samoa 2 at 175 DAP. With regards to the
different rates of nitrogen, both cultivars increased their RDM as nitrogen rate was
increased from 0 to 100 and then decreased at 200 Kg ha-1. Thus, the RDM of Samoa
1 increased from 0 (4.04 g/plant) to 100 kg ha-1 (4.88) and decreased again at 200
kg ha-1 (3.2 g/plant) at 70 DAP. Samoa 2 underwent a similar pattern of having a
-5
0
5
10
15
20
25
30
35 70 105 140 175
Dry
mat
ter (
g/pl
ant)
DAP
Samoa 1Samoa 2
35
higher RDM at 100 than decrease at 200 kg ha-1. Likewise, at 140 DAP the two
cultivars had similar responses to those at 70 DAP with higher responses at 100 than
200 Kg ha-1. Finally, both Samoa 1 and Samoa 2 lost dry matter at 175 DAP
irrespective of the amount of nitrogen used. This reduction in RDM is in accordance
with abovementioned growth stages of taro where the more total dry matter are
allocated to the corm and suckers than the LDM, PDM and RDM during the later
stages of growth. Additionally, the drop in RDM coincided with the drop in the total
rainfall shown in Fig 7. Goenaga (1995) showed that the roots dry matter increased
from 50 (3.5 g/plant) to 150 DAP (14 g/plant) and 50 (3.5 g/plant) to 80 DAP (12.5
g/plant) for the Blanca and Lila cultivars respectively. Their study concluded that the
varietal difference was due to the cultivars ability to utilize sunlight for
photosynthesis. In addition, Manrique (1994) also discovered that root growth rate of
taro increased from initial planting to 120 DAP.
4.4.3 Sucker (SDM)
Figure 16: “The effect of five harvest dates on the SDM of Samoa 1 and Samoa 2.”
The difference between the SDM of Samoa 1 and Samoa 2 at each harvest date is
highly significant (P < 0.001). Sucker production for both Samoa 1 and Samoa 2
started from 70 increasing up to 175 DAP. The above results are supported by Sivan
(1976) who reported a similar trend for the three taro cultivars he studied in Hawaii.
-40-20
020406080
100120140
70 105 140 175
Dry
mat
ter (
g/pl
ant)
DAP
Samoa 1Samoa 2
36
The results from his study suggested that SDM increased from planting until harvest.
However, the Hawaii taro cultivar had a much higher sucker dry matter than the
Tausala ni Samoa and QaweniUrau cultivars which was due to the Hawaii taro
suckers receiving more sunlight. With respect to the number of suckers produced
during the growth of taro, Cable and Asghar (1983) reported that the Tusitusi,
Paepae, Faeleele and Niue cultivars increased their suckers after six months of
planting. Goenaga (1995) also showed closely related results to those above in which
the SDM increased from the first harvest at 50 DAP (0 g/plant)to 180 DAP (170
g/plant) for the Lila cultivar. The Blanca cultivar increased its SDM from 0 to 210
g/plant during the same period. Therefore, the difference between the LAI of the two
cultivars was the reason why the Blanca cultivar had a higher SDM than Lila.
Furthermore, it was reported that there was a strong correlation (R2 = 0.98) between
the suckers dry matter and days after planting (Goenaga and Chardon, 1995).
4.4.4 Total (TDM)
Figure 17: “The effect of five harvest dates on the TDM of Samoa 1 and Samoa 2.”
The difference between the cultivars TDM at each harvest date is highly significant
(P < 0.001). The total dry matter of Samoa 1 and Samoa 2 increased from 35 to 175
DAP. The petioles and leaf blades dry matter had the largest contribution to the
overall increase in the total dry matter accumulation during the early stages of
-100
0
100
200
300
400
500
35 70 105 140 175
Dry
mat
ter (
g/pl
ant)
DAP
Samoa 1Samoa 2
37
growth while the corm and suckers dominated the later stages of growth. Samoa 2
had a higher TDM than Samoa 1 in most of the harvest dates and also at the different
rates of nitrogen. It was also reported that he total dry matters of the Hawaii, Tausala
ni Samoa and Qawe ni Urau cultivars were all reported to increase during the first
168 DAP (Sivan, 1976). Furthermore, Goenaga (1995) concluded that the total dry
matters of the Blanca and Lila cultivars also increased during their growth over a 12
months period.
4.4.5 Dry matter partitioning
4.4.6 Leaf blades
Figure 18: “The effect of five harvest dates on the dry matter partitioned to the leaf blades of Samoa 1 and Samoa 2.”
The difference in the partitioning of total dry matter to the leaf blades of Samoa 1
and Samoa 2 is highly significant (P < 0.001) at each harvest dates. The partitioning
of dry matter to the leaf blades of Samoa 1 and Samoa 2 slowly decreased from 35 to
175 DAP. Such that Samoa 1 received 20% of the total dry matter at 35 DAP, but
started to decline afterward to 6.6% at harvest. The leaf blades of Samoa 2 on the
other hand collected 28% and 6.6% at 35 and 175 DAP respectively. The partitioning
of LDM for Samoa 1 and Samoa 2 is in accordance with fact that leaf blades
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
35 70 105 140 175
DM
ratio
DAP
Samoa 1Samoa 2
38
received greater portions of the TDM early in the growth stages but as the taro plants
moved towards maturity CDM and SDM dominated in terms of TDM allocation.
The LDM of Samoa 2 declined, irrespective of the nitrogen rates used. A previous
study by Goenaga (1995) supported the above results. He suggested that during the
early growth periods a greater portion of the total dry matter is allocated to the leaf
blades and petioles. For example, the LDM of both the Blanca and Lila cultivars got
less dry matter at 200 DAP (0.02) than at 50 DAP (0.27). According to Goenaga, the
above response was possible since taro plants are autotrophic during the early stages
of growth and therefore used less assimilates from the planting materials.
4.4.7 Petioles
Figure 19: “The effect of five harvest dates on the dry matter partitioned to the petioles of Samoa 1 and Samoa 2”.
The partitioning of the total dry matter to the petioles at different harvest dates is
highly significant (P < .001). On the contrary, there is no significant difference as a
result of the nitrogen applied. The partitioning of dry matter to the petioles of Samoa
1 and Samoa 2 slowly decreased from 35 to 175 DAP. Ratios of dry matter
partitioned to the petioles of Samoa 1 and Samoa 2 accounted for at least 30% of the
total dry matter from 35 to 70 DAP. Afterwards, except for the magnitude, the
0
0.1
0.2
0.3
0.4
0.5
0.6
35 70 105 140 175
DM
ratio
DAP
Samoa 1Samoa 2
39
partitioning of dry matter from 105 to 175 DAP was similar for both cultivars. In the
case of the influence of nitrogen on the partitioning of PDM, noticeable increase in
PDM was recorded at 200 kg ha-1 (72%) for Samoa 1 at 70 DAP which was a huge
jump compared to 32% and 50% at 0 and 100 kg ha-1 respectively, however, these
were not statistically different. Therefore the above results had supported Goenaga’s
(1995) suggestions that the petioles dominated greater portions of the total dry matter
early during the growth of taro.
4.4.8 Corm
Figure 20: “The effect of five harvest dates on the dry matter partitioned to the corms of Samoa 1 and Samoa 2”.
The dry matter partitioned to the corm is highly significantly (P < 0.001) at each
harvest dates between Samoa 1 and Samoa 2. The dry matters partitioned to the corm
increased from approximately 10 to 50 % at 35 to 175 DAP for both Samoa 1 and
Samoa 2. Furthermore, the two cultivars had similar trends with respect to the CDM
they received from planting until harvest. There was no significant effect of added
nitrogen to the CDM of the two cultivars. However, Samoa 1 had more CDM at 0 kg
ha-1 than 100 and 200 kg ha-1 from 35 to 140 DAP. Samoa 2 also received large
portions of the total dry matter as the nitrogen rates were increased from 0 to 100 and
finally to 200 kg ha-1 during its six months of growth. These results are supported by
Goenaga (1995), where he found dry matter partitioned to taro corms increased
overtime
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
35 70 105 140 175
DM
ratio
DAP
Samoa 1Samoa 2
40
4.4.9 Roots
Table 2: “The effect of five harvest dates on the dry matter partitioned to the roots (%) of Samoa 1 and Samoa 2”
DAP
Cultivars 35 70 105 140 175
Samoa 1 4.0 5.4 3.3 3.7 1.1
Samoa 2 4.6 3.5 3.7 5.9 1.3
The difference in the dry matter partitioned to the roots of the two cultivars at each
harvest dates is highly significant (P < 0.001). However, no differences were
detected between cultivars or nitrogen rates. The portions of the total dry matter
partitioned to the roots of Samoa 1 and Samoa 2 changed a little during the early
stages of growth. For Samoa 1, the dry matter partitioned to the roots was 4% and
3% at 35 and 105 DAP respectively, while the roots of Samoa 2 also received 4% of
the total dry matter during the same periods. However, both cultivar roots received
fewer dry matters at harvest with Samoa 1 experiencing a 50% reduction while
Samoa 2 lost 33% of the total dry matter. Furthermore, the ratios to RDM of Samoa
1and Samoa 2 decline from 35 to 175 DAP irrespective of the amount of nitrogen
applied. A previous study by Goenaga (1995) also revealed the declining ratios of the
total dry matter partitioned to the roots as the taro plants moved towards maturity.
41
4.5.0 Suckers
Figure 21: “The effect of five harvest dates on the dry matter partitioned to the suckers of Samoa 1 and Samoa 2”.
The difference between the dry matter partitioned to the suckers of Samoa 1 and
Samoa 2 is highly significant (P < 0.001) at each harvest dates. The amounts of dry
matter received by the suckers of the two cultivars increased overtime from 70 to 175
DAP. Therefore the SDM ratios for Samoa 1 increased from 3 to 39% while Samoa 2
increased from 10 to 25% during six months of growth. In most cases, the
application of nitrogen increased the SDM ratios for Samoa 1, especially when the
rate was raised from 0 to 100 Kg ha-1. However, these increase were not significant.
Nevertheless, the dry matter partitioned to the suckers of Samoa 2 still increased
regardless of the nitrogen rates used. Additionally, there was no significant
difference between the cultivars with respect to their SDM ratios. On the contrary,
the difference between the SDM ratios at each harvests dates was significant (P <
0.001) at the 5% probability level. Likewise, Goenaga (1995) also suggested that the
SDM partitioning increased during the growth of two cultivars he studied in Puerto
Rico.
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
70 105 140 175
DM
ratio
DAP
Samoa 1Samoa 2
42
CHAPTER 5
5.1 General Discussions
Overall, at 35 DAP Samoa 2 dominated the first harvest in which it had more corms,
leaf blades, petioles and roots dry matters than Samoa 1. The second harvest at 70
DAP was also dominated by Samoa 2, having more dry matter than Samoa 1 in all
the different taro organs. Noticeably, the suckers started to emerge from the mother
plants for both cultivars at 70 DAP and the leaf blades, petioles and roots dry matter
rapidly increased.
Approximately halfway through the growing season at 105 DAP, a similar trend was
observed for the dry matter accumulations of Samoa 1 and Samoa 2. The dry matter
of various taro organs continued to increase three fold and Samoa 2 still dominated
Samoa 1 with respect to the magnitude of total dry matter accumulated. Furthermore,
real differences were found between the corm and roots dry matters of Samoa 1 and
Samoa 2. Even though Samoa 2 was still having higher leaf blades, petioles, corm,
roots and suckers dry matter than Samoa 1 at 140 DAP, the difference between the
two cultivars dry matter accumulations was starting to decrease. Additionally, the
increased accumulation in the total taro dry matter was also starting to decrease, in
contrast to the rapid increases observed at 70 and 105 DAP. Finally after six months
of planting (175 DAP) the leaf blades, petioles and roots dry matter for Samoa 1 and
Samoa 2 decreased while the corm and suckers dry matter increased.
It is clear from the dry matter accumulations of Samoa 1 and Samoa 2 that the two
cultivars had similar growth and development patterns. This is despite the cultivars
being different with respect to the accumulations of dry matter to various taro organs.
Therefore, from 35 to 175 DAP Samoa 2 had more leaf blades, petioles, corm, roots
and suckers dry matters than Samoa 1. The similarity of the two cultivars dry matter
accumulations might be explained by the fact that two cultivars were from the same
breeding cycle (Cycle 5) of the taro improvement project (Table 1).
With regards to the influence of different nitrogen rates on the dry matter
accumulation of Samoa 1 and Samoa 2, the results are in accordance with those
reported by other researchers. For example, De la Pena and Plucknett (1972) also
reported the accumulation of LDM, PDM and CDM of a taro cultivar (Lehua) in
43
Hawaii from 3 to 6 months of growth. They concluded that the LDM decreased from
2.1 to 1.4 g/plant during growth from 3 months to 6 months and the PDM was 2.2
and 1.6 g/plant at 3 and 6 months after planting respectively when no nitrogen was
applied. Further studies by De la Pena and Melchor (1984) also supported the fact
that the aboveground biomass was enhanced during the early stages until a certain
period late during growth in which the LDM and PDM declined while the CDM
continued to increase.
Prasad (1999) also reported that the Vula Ono cultivar in Fiji increased its LDM
when the nitrogen supply was raised from 0 (18%) to 100 kg ha-1 (23%). Likewise,
the CDM accumulated from 37.7% to 38.4% and the RDM increased from 16 to 17%
after the application of 100 kg ha-1 of nitrogen to the Vula Ono. The number of
suckers of both Vula Ono and Tausala ni Samoa increased from 1 to 2 and 2 to 4
respectively at 100 kg ha-1 of nitrogen. According to Hartemink et al (2000)
increasing the rate of applied nitrogen from 0 to 100 kg ha-1 increased the
aboveground biomass by 16.5%. The above results were also similar to those
presented by Osorio (2000) in Hawaii for the Bun Long cultivar. He concluded that
increasing the rate of nitrogen by 100% will improve the total dry weight of taro
from 8 to 14.9 g/plant.
Jacobs (1993) supported the above results when he tested the dry matter
accumulation and partitioning of traditional Samoan and improved taro cultivars
under varying nitrogen supply. In conclusion, he suggested that higher levels of
nitrogen will increase the leaf area and the number of leaves of traditional and
improved taro cultivars during the early stages of growth. Therefore, dry matter
accumulation and partitioning of the leaf blades and petioles will be higher than the
roots and corms after the application of higher levels of nitrogen. Specifically, Prasad
(1999) had shown that the RDM and the number of suckers of Vula Ono all
increased after improving the nitrogen fertilization rates from 0 to 200 kg ha-1.
Furthermore, Osorio et al (2000) proved that enhancing the nitrogen supply by two
folds increases the total dry weights of the Bun Long taro cultivar from 8 to 14.3
g/plant. Lastly, the application of nitrogen had little influence on the roots and
suckers dry matters of Samoa 1 and Samoa 2. Evidently, the application of nitrogen
44
fertilizer to these two cultivars increased their aboveground biomass as in the case of
the leaf blades for Samoa 2 and petioles for Samoa 1.
The LAI, plant height, number of leaves and suckers were also measured during the
six months of the study to provide a better understanding of the physiological
characteristics of Samoa 1 and Samoa 2 especially their growth and development.
Thus, as shown in Figs 12 to 15, the LAI for Samoa 1 and Samoa 2 increased from
planting until they both reached maximum LAI’s (Samoa 1 = 2.2; Samoa 2 = 2.9) at
140 DAP. Afterwards, the two cultivars LAI declined at harvest.
Similar to the LAI, the maximum heights of 115 and 114cm were recorded for
Samoa 1 and Samoa 2 respectively at 140 DAP with the application of 100 kg ha-1 of
nitrogen. For the leaves production, Samoa 2 (13) had more leaves than Samoa 1
(10) while the application of different rates of nitrogen had no significant effect on
the number of leaves produced by each cultivar. However, the number of suckers
produced by Samoa 1 and Samoa 2 peaked at 140 DAP and the addition of 100 kg
ha-1 of nitrogen caused the two cultivars to produce their highest number of suckers.
After considering the pot trial and field trial, there were similarities in the results of
the two experiments. For example, the LDM for Samoa 1 from the pot experiment
and field trial both improved after the application of 100 kg ha-1 of nitrogen.
Moreover, the heights of Samoa 1 and Samoa 2 from the pot and field trials had
revealed that the two cultivars increased their heights irrespective of the nitrogen
from planting until 140 DAP.
Furthermore, the difference between the cultivar heights as a result of the varying
supply of nitrogen was significant in both experiments. While the maximum LAIs for
both cultivars were recorded within 105 and 140 DAP in the pot as well as the field
trial, it was evident that the difference between the LAIs of Samoa 1and Samoa 2
after six months was significant in both trials. Finally, the leaf production for Samoa
1 and Samoa 2 in the two experiments increased overtime regardless of the amount
of nitrogen applied. All in all, the pot experiment and the field trial complemented
each other with regards to the development and growth of Samoa 1 and Samoa 2 as
well as their responses to the different rates of nitrogen.
45
Lastly, the weather data collected from the Watchdog weather station (Figure 7) also
revealed that at 175 DAP (July) the total rainfalls drastically declined from 100.3 to
12.7 mm. On the other hand, the mean temperatures at 140 and 175 DAP were
almost the same at 26 and 26.50C respectively. Hence, the changes in environmental
parameters such as the rainfall distribution within the growing season may also
contribute to the trends observed in the growth and development of Samoa 1 and
Samoa 2. This is important for future research to explore in details since the two taro
cultivars had recently been released and their values both for local consumption and
export is attracting the attention of researchers to study Samoa 1 and Samoa 2.
5.2 Conclusion
Sivan (1976) proposed three growth phases for taro after he studied the dry matter
accumulation and partitioning of three taro cultivars (Hawaii, Tausala ni Samoa and
Qawe ni Urau) in Fiji. The first phase took place very early during growth in which
the taro plants lost dry matter in the first two weeks and then slowly accumulated dry
matter during the next six weeks. The second phase (“grand growth period”)
comprised of rapid accumulation of dry matter by the leaf blades and petiole in
where they reached peak values at 168 DAP, while the corm continued to
accumulate dry matter until harvest at 336 DAP. The final phase was recognised as
the stage in which the total dry matter started to decline mainly because of the leaf
blades and petioles losing dry matters.
According to Goenaga (1995), the growth of the taro cultivars (Blanca and Lila) in
Puerto Rico were also characterized by three distinct stages. Stage 1 was dominated
by the low rates of total dry matter accumulation during the first 48 DAP, followed
by the rapid growth of total dry matter until 159 DAP in which all plant parts
experience improved dry matter accumulations. The third and final stage involved
continuous rise in the total dry matter of the two cultivars which was mainly due to
the dry matter accumulations of the corm and suckers.
For the total dry matter accumulations of Samoa 1 and Samoa 2 in Fig 17 the
cultivars had similar growth patterns from 35 to 175 DAP. For the first 35 DAP there
was a slow rate of dry matter accumulation. Afterwards, the total dry matter
accumulated very rapidly until 160 DAP. Finally, the total dry matter which is
46
dominated by the corm and suckers dry matters gradually accumulated until the final
harvest at 175 DAP. Therefore, the dry matter accumulation of Samoa 1 and Samoa
2 is in accordance with the other studies mentioned above by Sivan (1976) and
Goenaga (1995).
The results from the pot and field trial were compared with only the dry matter
accumulation at 175 DAP from the field trial used since it had the same growth
period of six months with the pot the trial. Therefore, the LDM accumulations in the
two experiments generated similar results. For example, Samoa 1 increased its LDM
as the rate of nitrogen was raised to higher levels while Samoa 2 reached an optimum
LDM of 19 and 26 g/plant in the pot and field trial respectively. Furthermore, the
PDM and CDM in the two experiments followed similar trends with respect to the
impact of different rates of nitrogen on the dry matter accumulations of Samoa 1 and
Samoa 2. The RDM (5 g/plant) of Samoa 1 was almost the same in the two
experiments.
Finally, the SDM and TDM of the taro cultivars in the two trials also followed a
similar pattern with respect to their responses to the different rates of nitrogen, even
though there was a substantial difference in the magnitudes of the SDM and TDM in
the pot and field trial. The field trial as expected had higher values than the pot
experiment since taro plants in the field had unlimited supply of resource such as soil
nutrients and water while the plants in the pots had restricted access to the same
resources.
In the case of dry matter partitioning, a previous study by Goenaga (1995) revealed
that early during the growth season (82 DAP) of taro, plants allocated a greater
percentage of the total dry matter to the leaf blades and petioles which accounts for at
least 40% of the total dry matter. Afterwards (from 100 to 350 DAP) the corm and
suckers received greater portions of the total dry matter while the partitioning to the
leaf blades and petioles decreased significantly. Hence, the partitioning of dry matter
in Samoa 1 and Samoa 2 is also supported by the abovementioned study by Goenaga
in 1995.
In conclusion, it was noted from the results that the aboveground biomass (leaf
blades and petioles) accumulated very rapidly during the first three months, thus had
higher dry matters than the other plant parts while the corm and suckers dominated
47
the last three months of growth. The dry matter partitioning on the other hand was
also similar in both cultivars in which the LDM and PDM of Samoa 1 and Samoa 2
received greater portions of the total dry matter at 35 and 70 DAP, afterwards (105,
140 and 175 DAP), the LDM and PDM lost dry matter which instead were allocated
towards the corms and suckers.
48
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57
APPENDICES.
Appendix 1: Nitrogen rates calculations
1.1 Pot Experiment
Urea 46% N, therefore 100 kg urea provides 46 kg N
Question 1: To supply 100 kg N/ha, how much urea should be applied:
100 kg = 46 kg N
X kg = 100 kg N
Answer 1: X = (100 kg N/46 kgN) * 100 kg urea = 217 kg
Area of the pot: Volume of pot/height = 5 * 10-3 m3/0.4m
Area = 1.25 * 10-2 m2
217 kg urea = 10,000 m2
X = 1.25 * 10-2 m2
Therefore X = 2.71 * 10-4 kg urea or 0.271 g urea per pot
And to supply 200 kg N/ha, we apply 5.42 * 10-4 kg urea or 0.542 g urea per pot, to supply 50 kg N/ha, we apply 13.5 * 10-4 kg urea per pot.
1.2 Field Experiment
Urea 46% N, therefore 100 kg urea provides 46 kg N
Question 1: To supply 100 kg N/ha, how much urea should be applied:
100 kg = 46 kg N
X kg = 100 kg N
Answer 1: X = (100 kg N/46 kgN) * 100 kg urea = 217 kg
So, 217 kg urea/ha will provide 100 kg N/ha
Question 2: To supply 100 kg N/ha (ie; 217 kg urea/ha) how many g urea should be applied per m2 ?
1 ha = 100 m * 100 m = 10,000 m2
217 kg urea per ha
58
217,000 g urea per 10,000 m2 [Divide both sides by 10,000]
21.7 g urea per m2
Answer 2: To supply 100 kg N/ha, we apply 21.7 g urea per m2
And to supply 200 kg N/ha, we apply 43.4 urea per m2
59
Appendix 2: Field experiment Layout.
Block 1 C1 C2
N0 H3 H5 H1 H4 H2 H3 H5 H2 H4 H1 N200 H2 H4 H3 H5 H1 H2 H1 H3 H5 H4 N100 H5 H2 H4 H3 H1 H1 H2 H5 H4 H3
Block 2 C2 C1 N100 H1 H2 H5 H3 H4 H4 H5 H2 H3 H1 N200 H2 H4 H3 H5 H3 H3 H1 H5 H4 H2 N0 H4 H3 H1 H2 H5 H1 H2 H4 H5 H3
Block 3 C1 C2 N200 H3 H4 H5 H1 H2 H4 H3 H5 H1 H2 N100 H5 H1 H2 H4 H3 H2 H5 H1 H3 H4 N0 H1 H2 H4 H3 H5 H5 H4 H1 H3 H2
C1: Samoa 1
C2: Samoa 2
H1: Harvest 1 (35 DAP), H2: Harvest 2 (70 DAP), H3: Harvest 3 (105 DAP), H4: Harvest 4 (140 DAP), H5: Harvest 5 (175 DAP)
N0: 0 kg ha-1, N100: 100 kg ha-1, N200: 200 kg ha-1of nitrogen.
60
Appendix 3: Pot Experiment Analysis of variance Analysis of variance Variate: Height Source of variation d.f. s.s. m.s. v.r. F pr. cultivar 1 521.64 521.64 33.12 <.001 Rates 4 442.42 110.60 7.02 0.002 DAP 4 1518.88 379.72 24.11 <.001 cultivar.Rates 4 502.63 125.66 7.98 <.001 cultivar.DAP 4 105.19 26.30 1.67 0.206 Rates.DAP 16 274.29 17.14 1.09 0.434 Residual 16 252.03 15.75 Total 49 3617.10 Tables of means Variate: Height Grand mean 63.16 cultivar 1 2 66.39 59.93 Rates 1 2 3 4 5 62.77 67.75 61.88 64.62 58.77 DAP 35 70 105 140 175 55.97 57.82 67.45 70.40 64.15 cultivar Rates 1 2 3 4 5 1 63.25 69.45 61.80 71.10 66.35 2 62.30 66.05 61.95 58.15 51.20 cultivar DAP 35 70 105 140 175 1 58.35 63.15 71.70 73.45 65.30 2 53.60 52.50 63.20 67.35 63.00 Rates DAP 35 70 105 140 175 1 56.25 61.88 64.00 68.88 62.88 2 64.38 61.62 71.38 74.25 67.12 3 55.88 55.12 65.62 69.25 63.50 4 51.75 56.38 71.12 73.62 70.25 5 51.62 54.12 65.12 66.00 57.00
61
Analysis of variance Variate: Number of leaves Source of variation d.f. s.s. m.s. v.r. F pr. cultivar 1 4.0613 4.0613 25.68 <.001 Rates 4 2.1800 0.5450 3.45 0.033 DAP 4 31.3175 7.8294 49.51 <.001 cultivar.Rates 4 0.4450 0.1112 0.70 0.601 cultivar.DAP 4 3.4325 0.8581 5.43 0.006 Rates.DAP 16 0.9450 0.0591 0.37 0.971 Residual 16 2.5300 0.1581 Total 49 44.9112 Tables of means Variate: Number of leaves. Grand mean 4. cultivar 1 2 4. 4. Rates 1 2 3 4 5 4. 4. 4. 4. 4. DAP 35 70 105 140 175 3. 5. 5. 4. 3. cultivar Rates 1 2 3 4 5 1 4. 4. 4. 4. 4. 2 4. 5. 4. 5. 4. cultivar DAP 35 70 105 140 175 1 3. 5. 5. 4. 3. 2 3. 5. 6. 5. 4. Rates DAP 35 70 105 140 175 1 3. 4. 5. 4. 3. 2 4. 5. 6. 5. 4. 3 3. 5. 5. 4. 3. 4 3. 5. 6. 5. 3. 5 3. 5. 5. 4. 3.
62
Analysis of variance Variate: LAI Source of variation d.f. s.s. m.s. v.r. F pr. cultivar 1 1.20125 1.20125 35.84 <.001 Rates 4 0.13236 0.03309 0.99 0.442 DAP 4 3.81106 0.95277 28.42 <.001 cultivar.Rates 4 0.35064 0.08766 2.62 0.074 cultivar.DAP 4 0.10546 0.02636 0.79 0.551 Rates.DAP 16 0.44878 0.02805 0.84 0.637 Residual 16 0.53630 0.03352 Total 49 6.58585 Tables of means Variate: LAI Grand mean 1.307 cultivar 1 2 1.152 1.462 Rates 1 2 3 4 5 1.243 1.340 1.258 1.382 1.312 DAP 35 70 105 140 175 1.150 1.449 1.639 1.445 0.852 cultivar Rates 1 2 3 4 5 1 1.022 1.182 1.092 1.150 1.314 2 1.464 1.498 1.424 1.614 1.310 cultivar DAP 35 70 105 140 175 1 1.034 1.286 1.444 1.234 0.762 2 1.266 1.612 1.834 1.656 0.942 Rates DAP 35 70 105 140 175 1 1.020 1.360 1.645 1.350 0.840 2 1.045 1.555 1.700 1.425 0.975 3 1.030 1.380 1.575 1.540 0.765 4 1.530 1.410 1.580 1.470 0.920 5 1.125 1.540 1.695 1.440 0.760
63
Analysis of variance Variate: LDM Source of variation d.f. s.s. m.s. v.r. F pr. block 3 0.6996 0.2332 1.61 0.239 Cultivars 1 271.1483 271.1483 1869.95 <.001 Nitrogen rates 4 217.1416 54.2854 374.37 <.001 block.Cultivars 3 0.4152 0.1384 0.95 0.445 block.Nitrogen rates 12 1.3385 0.1115 0.77 0.672 Cultivars.Nitrogen rates 4 276.1634 69.0408 476.13 <.001 Residual 12 1.7400 0.1450 Total 39 768.6467 Tables of means Variate: LDM Grand mean 6.882 block 1 2 3 4 6.977 7.018 6.854 6.678 Cultivars 1 2 4.278 9.485 Nitrogen rates 0 50 100 150 200 5.303 11.287 7.159 5.752 4.908 block Cultivars 1 2 1 4.346 9.608 2 4.259 9.777 3 4.344 9.364 4 4.164 9.193 blockNitrogen rates 0 50 100 150 200 1 5.425 11.444 7.236 5.849 4.933 2 5.451 11.384 7.334 6.000 4.922 3 5.274 11.715 6.939 5.552 4.789 4 5.062 10.603 7.127 5.609 4.990 CultivarsNitrogen rates 0 50 100 150 200 1 1.775 4.697 3.899 6.895 4.125 2 8.831 17.876 10.419 4.610 5.691 Least significant differences of means (5% level) Table block Cultivars Nitrogen rates block Cultivars
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rep. 10 20 8 5 d.f. 12 12 12 12 l.s.d. 0.3710 0.2624 0.4148 0.5247 Table block Cultivars Nitrogen rates Nitrogen rates rep. 2 4 d.f. 12 12 l.s.d. 0.8297 0.5867 Analysis of variance Variate: PDM Source of variation d.f. s.s. m.s. v.r. F pr. block 3 3.1603 1.0534 1.25 0.335 Cultivars 1 598.5494 598.5494 711.18 <.001 Nitrogen rates 4 1146.8387 286.7097 340.66 <.001 block.Cultivars 3 3.0102 1.0034 1.19 0.354 block.Nitrogen rates 12 10.4908 0.8742 1.04 0.474 Cultivars.Nitrogen rates 4 470.6696 117.6674 139.81 <.001 Residual 12 10.0995 0.8416 Total 39 2242.8186 Tables of means Variate: PDM Grand mean 17.22 block 1 2 3 4 17.45 17.46 17.18 16.77 Cultivars 1 2 13.35 21.08 Nitrogen rates 0 50 100 150 200 12.00 25.74 14.74 21.11 12.50 block Cultivars 1 2 1 13.54 21.36 2 13.18 21.75 3 13.65 20.72 4 13.02 20.51 blockNitrogen rates 0 50 100 150 200 1 12.25 25.99 14.99 21.41 12.61 2 12.20 25.55 15.26 21.92 12.38 3 12.03 27.12 14.26 20.31 12.19
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4 11.51 24.29 14.43 20.78 12.83 CultivarsNitrogen rates 0 50 100 150 200 1 6.00 17.22 12.29 17.06 14.17 2 17.99 34.25 17.19 25.16 10.83 Least significant differences of means (5% level) Table block Cultivars Nitrogen rates block Cultivars rep. 10 20 8 5 d.f. 12 12 12 12 l.s.d. 0.894 0.632 0.999 1.264 Table block Cultivars Nitrogen rates Nitrogen rates rep. 2 4 d.f. 12 12 l.s.d. 1.999 1.413 Analysis of variance Variate: CDM Source of variation d.f. s.s. m.s. v.r. F pr. block 3 44.38 14.79 0.90 0.467 Cultivars 1 3090.99 3090.99 189.04 <.001 Nitrogen rates 4 4166.79 1041.70 63.71 <.001 block.Cultivars 3 52.49 17.50 1.07 0.398 block.Nitrogen rates 12 165.11 13.76 0.84 0.615 Cultivars.Nitrogen rates 4 5241.45 1310.36 80.14 <.001 Residual 12 196.21 16.35 Total 39 12957.42 Tables of means Variate: CDM Grand mean 74.30 block 1 2 3 4 75.26 75.08 74.24 72.60 Cultivars 1 2 65.51 83.09 Nitrogen rates 0 50 100 150 200 66.89 89.87 75.94 78.68 60.10
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block Cultivars 1 2 1 66.46 84.07 2 64.56 85.60 3 66.93 81.56 4 64.08 81.11 blockNitrogen rates 0 50 100 150 200 1 68.00 90.61 77.16 79.93 60.60 2 66.66 88.77 78.49 81.91 59.56 3 68.10 95.15 73.51 75.85 58.61 4 64.79 84.94 74.59 77.05 61.63 CultivarsNitrogen rates 0 50 100 150 200 1 52.72 67.40 59.16 81.21 67.04 2 81.06 112.34 92.71 76.16 53.17 Least significant differences of means (5% level) Table block Cultivars Nitrogen rates block Cultivars rep. 10 20 8 5 d.f. 12 12 12 12 l.s.d. 3.940 2.786 4.405 5.572 Table block Cultivars Nitrogen rates Nitrogen rates rep. 2 4 d.f. 12 12 l.s.d. 8.810 6.230 Analysis of variance Variate: RDM Source of variation d.f. s.s. m.s. v.r. F pr. block 3 0.5014 0.1671 1.55 0.252 Cultivars 1 335.0279 335.0279 3108.67 <.001 Nitrogen rates 4 61.4739 15.3685 142.60 <.001 block.Cultivars 3 0.8145 0.2715 2.52 0.107 block.Nitrogen rates 12 1.5985 0.1332 1.24 0.360 Cultivars.Nitrogen rates 4 44.8144 11.2036 103.96 <.001 Residual 12 1.2933 0.1078 Total 39 445.5237 Tables of means Variate: RDM Grand mean 7.346
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block 1 2 3 4 7.425 7.468 7.310 7.179 Cultivars 1 2 4.452 10.240 Nitrogen rates 0 50 100 150 200 6.501 8.310 6.395 9.309 6.213 block Cultivars 1 2 1 4.501 10.349 2 4.371 10.564 3 4.611 10.009 4 4.323 10.036 blockNitrogen rates 0 50 100 150 200 1 6.649 8.361 6.465 9.435 6.217 2 6.675 8.140 6.552 9.650 6.321 3 6.471 8.868 6.198 8.947 6.066 4 6.209 7.873 6.364 9.203 6.247 CultivarsNitrogen rates 0 50 100 150 200 1 2.285 7.331 3.511 6.053 3.078 2 10.717 9.290 9.279 12.564 9.348 Least significant differences of means (5% level) Table block Cultivars Nitrogen rates block Cultivars rep. 10 20 8 5 d.f. 12 12 12 12 l.s.d. 0.3199 0.2262 0.3576 0.4524 Table block Cultivars Nitrogen rates Nitrogen rates rep. 2 4 d.f. 12 12 l.s.d. 0.7153 0.5058
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Analysis of variance Variate: SDM Source of variation d.f. s.s. m.s. v.r. F pr. block 3 0.1571 0.0524 0.31 0.818 Cultivars 1 304.5221 304.5221 1802.28 <.001 Nitrogen rates 4 215.9472 53.9868 319.51 <.001 block.Cultivars 3 0.2625 0.0875 0.52 0.678 block.Nitrogen rates 12 2.2091 0.1841 1.09 0.442 Cultivars.Nitrogen rates 4 77.6651 19.4163 114.91 <.001 Residual 12 2.0276 0.1690 Total 39 602.7907 Tables of means Variate: SDM Grand mean 5.370 block 1 2 3 4 5.442 5.353 5.408 5.277 Cultivars 1 2 8.129 2.611 Nitrogen rates 0 50 100 150 200 3.506 5.519 2.179 8.624 7.022 block Cultivars 1 2 1 8.241 2.644 2 7.997 2.709 3 8.271 2.546 4 8.008 2.545 blockNitrogen rates 0 50 100 150 200 1 3.550 5.485 2.275 8.780 7.122 2 3.421 5.154 2.357 9.018 6.814 3 3.625 6.141 2.095 8.339 6.841 4 3.429 5.297 1.990 8.359 7.309 CultivarsNitrogen rates 0 50 100 150 200 1 3.820 8.903 4.358 12.334 11.230 2 3.192 2.135 0.000 4.914 2.813 Least significant differences of means (5% level) Table block Cultivars Nitrogen rates block Cultivars
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rep. 10 20 8 5 d.f. 12 12 12 12 l.s.d. 0.4005 0.2832 0.4478 0.5664 Table block Cultivars Nitrogen rates Nitrogen rates rep. 2 4 d.f. 12 12 l.s.d. 0.8956 0.6333 Analysis of variance Variate: TDM Source of variation d.f. s.s. m.s. v.r. F pr. block 3 105.31 35.10 0.99 0.431 Cultivars 1 9483.19 9483.19 266.78 <.001 Nitrogen rates 4 14022.34 3505.58 98.62 <.001 block.Cultivars 3 119.59 39.86 1.12 0.379 block.Nitrogen rates 12 384.16 32.01 0.90 0.570 Cultivars.Nitrogen rates 4 11439.88 2859.97 80.46 <.001 Residual 12 426.56 35.55 Total 39 35981.02 Tables of means Variate: TDM Grand mean 111.11 block 1 2 3 4 112.56 112.38 111.00 108.50 Cultivars 1 2 95.71 126.51 Nitrogen rates 0 50 100 150 200 94.19 140.72 106.41 123.48 90.75 block Cultivars 1 2 1 97.09 128.03 2 94.36 130.40 3 97.80 124.20 4 93.60 123.40 blockNitrogen rates 0 50 100 150 200 1 95.87 141.89 108.13 125.40 91.48 2 94.40 139.00 110.00 128.50 90.00
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3 95.50 149.00 103.00 119.00 88.50 4 91.00 133.00 104.50 121.00 93.00 CultivarsNitrogen rates 0 50 100 150 200 1 66.60 105.55 83.22 123.55 99.64 2 121.79 175.89 129.60 123.40 81.85 Least significant differences of means (5% level) Table block Cultivars Nitrogen rates block Cultivars rep. 10 20 8 5 d.f. 12 12 12 12 l.s.d. 5.809 4.108 6.495 8.216 Table block Cultivars Nitrogen rates Nitrogen rates rep. 2 4 d.f. 12 12 l.s.d. 12.990 9.185
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Appendix 4: Field Trial Analysis of variance Analysis of variance Variate: Number of suckers. Source of variation d.f. s.s. m.s. v.r. F pr. Block stratum 2 144.20 72.10 4.38 Block.Variety stratum Variety 1 51.38 51.38 3.12 0.219 Residual 2 32.96 16.48 1.01 Block.Variety.Nitrogen_rates stratum Nitrogen_rates 2 30.20 15.10 0.92 0.436 Variety.Nitrogen_rates 2 0.69 0.34 0.02 0.979 Residual 8 130.98 16.37 1.02 Block.Variety.Nitrogen_rates.DAP stratum DAP 4 2442.40 610.60 37.87 <.001 Variety.DAP 4 121.51 30.38 1.88 0.129 Nitrogen_rates.DAP 8 111.13 13.89 0.86 0.555 Variety.Nitrogen_rates.DAP 8 39.09 4.89 0.30 0.961 Residual 48 773.87 16.12 Total 89 3878.40 Tables of means Variate: Number suckers Grand mean 6.80 Variety 1 2 6.04 7.56 Nitrogen_rates 1 2 3 6.93 7.43 6.03 DAP 35 70 105 140 175 0.00 2.67 5.89 13.56 11.89 Variety Nitrogen_rates 1 2 3 1 6.13 6.60 5.40 2 7.73 8.27 6.67 Variety DAP 35 70 105 140 175 1 0.00 0.56 3.67 13.67 12.33 2 0.00 4.78 8.11 13.44 11.44
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Nitrogen_rates DAP 35 70 105 140 175 1 0.00 2.17 7.17 12.83 12.50 2 0.00 3.33 5.33 17.00 11.50 3 0.00 2.50 5.17 10.83 11.67 VarietyNitrogen_rates DAP 35 70 105 140 175 1 1 0.00 0.33 4.00 12.00 14.33 2 0.00 1.33 3.67 17.33 10.67 3 0.00 0.00 3.33 11.67 12.00 2 1 0.00 4.00 10.33 13.67 10.67 2 0.00 5.33 7.00 16.67 12.33 3 0.00 5.00 7.00 10.00 11.33 Standard errors of means Table VarietyNitrogen_rates DAP Variety Nitrogen_rates rep. 45 30 18 15 e.s.e. 0.605 0.739 0.946 1.046 d.f. 2 8 48 8.98 Except when comparing means with the same level(s) of Variety 1.045 d.f. 8 Table VarietyNitrogen_rates Variety DAP DAPNitrogen_rates DAP rep. 9 6 3 e.s.e. 1.341 1.642 2.322 d.f. 29.48 54.42 56.12 Except when comparing means with the same level(s) of Variety 1.338 2.322 d.f. 48 54.42 Nitrogen_rates 1.639 d.f. 48 Variety.Nitrogen_rates 2.318 d.f. 48 Variety.DAP 2.322 d.f. 54.42 Standard errors of differences of means Table VarietyNitrogen_rates DAP Variety Nitrogen_rates rep. 45 30 18 15
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s.e.d. 0.856 1.045 1.338 1.479 d.f. 2 8 48 8.98 Except when comparing means with the same level(s) of Variety 1.477 d.f. 8 Table VarietyNitrogen_rates Variety DAP DAPNitrogen_rates DAP rep. 9 6 3 s.e.d. 1.897 2.322 3.284 d.f. 29.48 54.42 56.12 Except when comparing means with the same level(s) of Variety 1.893 3.284 d.f. 48 54.42 Nitrogen_rates 2.318 d.f. 48 Variety.Nitrogen_rates 3.278 d.f. 48 Variety.DAP 3.284 d.f. 54.42 Least significant differences of means (5% level) Table VarietyNitrogen_rates DAP Variety Nitrogen_rates rep. 45 30 18 15 l.s.d. 3.682 2.409 2.691 3.347 d.f. 2 8 48 8.98 Except when comparing means with the same level(s) of Variety 3.407 d.f. 8 Table VarietyNitrogen_rates Variety DAP DAPNitrogen_rates DAP rep. 9 6 3 l.s.d. 3.877 4.654 6.579 d.f. 29.48 54.42 56.12 Except when comparing means with the same level(s) of Variety 3.806 6.582 d.f. 48 54.42 Nitrogen_rates 4.661 d.f. 48 Variety.Nitrogen_rates 6.592
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d.f. 48 Variety.DAP 6.582 d.f. 54.42 Analysis of variance. Variate: Height Source of variation d.f. s.s. m.s. v.r. F pr. Blk stratum 2 1039.20 519.60 0.46 Blk.Var stratum Var 1 711.21 711.21 0.63 0.512 Residual 2 2272.62 1136.31 2.16 Blk.Var.N stratum N 2 5195.40 2597.70 4.94 0.040 Var.N 2 1848.16 924.08 1.76 0.233 Residual 8 4204.71 525.59 5.60 Blk.Var.N.DAP stratum DAP 4 24117.29 6029.32 64.29 <.001 Var.DAP 4 208.62 52.16 0.56 0.696 N.DAP 8 3056.71 382.09 4.07 <.001 Var.N.DAP 8 725.51 90.69 0.97 0.473 Residual 48 4501.47 93.78 Total 89 47880.90 Tables of means Variate: Height Grand mean 81.7 Var 1 2 78.9 84.5 N 1 2 3 75.5 92.4 77.2 DAP 35 70 105 140 175 52.8 74.6 90.9 97.0 93.2 Var N 1 2 3 1 77.5 90.8 68.3 2 73.5 94.0 86.1 Var DAP 35 70 105 140 175
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1 48.0 74.0 89.2 94.0 89.2 2 57.6 75.1 92.7 100.0 97.2 N DAP 35 70 105 140 175 1 52.8 69.2 81.0 87.7 86.8 2 51.0 78.7 109.3 114.5 108.5 3 54.5 75.8 82.5 88.8 84.3 Var N DAP 35 70 105 140 175 1 1 56.3 76.0 79.7 87.0 88.7 2 44.3 74.7 111.3 115.0 108.7 3 43.3 71.3 76.7 80.0 70.3 2 1 49.3 62.3 82.3 88.3 85.0 2 57.7 82.7 107.3 114.0 108.3 3 65.7 80.3 88.3 97.7 98.3 Standard errors of means Table Var N DAP Var N rep. 45 30 18 15 e.s.e. 5.03 4.19 2.28 6.97 d.f. 2 8 48 6.11 Except when comparing means with the same level(s) of Var 5.92 d.f. 8 Table Var N Var DAP DAP N DAP rep. 9 6 3 e.s.e. 5.80 5.48 8.58 d.f. 3.52 21.66 13.55 Except when comparing means with the same level(s) of Var 3.23 7.75 d.f. 48 21.66 N 3.95 d.f. 48 Var.N 5.59 d.f. 48 Var.DAP 7.75 d.f. 21.66 Standard errors of differences of means Table Var N DAP Var N rep. 45 30 18 15 s.e.d. 7.11 5.92 3.23 9.86 d.f. 2 8 48 6.11 Except when comparing means with the same level(s) of
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Var 8.37 d.f. 8 Table Var N Var DAP DAP N DAP rep. 9 6 3 s.e.d. 8.20 7.75 12.13 d.f. 3.52 21.66 13.55 Except when comparing means with the same level(s) of Var 4.57 10.96 d.f. 48 21.66 N 5.59 d.f. 48 Var.N 7.91 d.f. 48 Var.DAP 10.96 d.f. 21.66 Least significant differences of means (5% level) Table Var N DAP Var N rep. 45 30 18 15 l.s.d. 30.58 13.65 6.49 24.03 d.f. 2 8 48 6.11 Except when comparing means with the same level(s) of Var 19.30 d.f. 8 Table Var N Var DAP DAP N DAP rep. 9 6 3 l.s.d. 24.03 16.09 26.11 d.f. 3.52 21.66 13.55 Except when comparing means with the same level(s) of Var 9.18 22.75 d.f. 48 21.66 N 11.24 d.f. 48 Var.N 15.90 d.f. 48 Var.DAP 22.75 d.f. 21.66 Analysis of variance
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Variate: Number of leaves. Source of variation d.f. s.s. m.s. v.r. F pr. blk stratum 2 2.2889 1.1444 3.32 blk.Var stratum Var 1 71.1111 71.1111 206.45 0.005 Residual 2 0.6889 0.3444 1.63 blk.Var.N stratum N 2 1.4889 0.7444 3.53 0.080 Var.N 2 1.7556 0.8778 4.16 0.058 Residual 8 1.6889 0.2111 0.84 blk.Var.N.DAP stratum DAP 4 807.6000 201.9000 807.60 <.001 Var.DAP 4 18.4444 4.6111 18.44 <.001 N.DAP 8 6.7333 0.8417 3.37 0.004 Var.N.DAP 8 2.0222 0.2528 1.01 0.440 Residual 48 12.0000 0.2500 Total 89 925.8222 Tables of means Variate: leaf number Grand mean 7.844 Var 1 2 6.956 8.733 N 1 2 3 7.667 7.900 7.967 DAP 35 70 105 140 175 3.000 6.278 8.278 10.167 11.500 Var N 1 2 3 1 6.733 7.200 6.933 2 8.600 8.600 9.000 Var DAP 35 70 105 140 175 1 3.000 5.222 7.000 9.111 10.444 2 3.000 7.333 9.556 11.222 12.556 N DAP 35 70 105 140 175 1 3.000 6.333 8.333 10.000 10.667
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2 3.000 6.500 8.167 10.167 11.667 3 3.000 6.000 8.333 10.333 12.167 Var N DAP 35 70 105 140 175 1 1 3.000 5.000 7.000 9.000 9.667 2 3.000 6.000 7.000 9.333 10.667 3 3.000 4.667 7.000 9.000 11.000 2 1 3.000 7.667 9.667 11.000 11.667 2 3.000 7.000 9.333 11.000 12.667 3 3.000 7.333 9.667 11.667 13.333 Standard errors of means Table Var N DAP Var N rep. 45 30 18 15 e.s.e. 0.0875 0.0839 0.1179 0.1305 d.f. 2 8 48 7.20 Except when comparing means with the same level(s) of Var 0.1186 d.f. 8 Table Var N Var DAP DAP N DAP rep. 9 6 3 e.s.e. 0.1728 0.2009 0.2893 d.f. 22.55 55.55 52.72 Except when comparing means with the same level(s) of Var 0.1667 0.2841 d.f. 48 55.55 N 0.2041 d.f. 48 Var.N 0.2887 d.f. 48 Var.DAP 0.2841 d.f. 55.55 Standard errors of differences of means Table Var N DAP Var N rep. 45 30 18 15 s.e.d. 0.1237 0.1186 0.1667 0.1846 d.f. 2 8 48 7.20 Except when comparing means with the same level(s) of Var 0.1678 d.f. 8 Table Var N Var
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DAP DAP N DAP rep. 9 6 3 s.e.d. 0.2444 0.2841 0.4092 d.f. 22.55 55.55 52.72 Except when comparing means with the same level(s) of Var 0.2357 0.4018 d.f. 48 55.55 N 0.2887 d.f. 48 Var.N 0.4082 d.f. 48 Var.DAP 0.4018 d.f. 55.55 Least significant differences of means (5% level) Table Var N DAP Var N rep. 45 30 18 15 l.s.d. 0.5324 0.2736 0.3351 0.4340 d.f. 2 8 48 7.20 Except when comparing means with the same level(s) of Var 0.3869 d.f. 8 Table Var N Var DAP DAP N DAP rep. 9 6 3 l.s.d. 0.5062 0.5693 0.8208 d.f. 22.55 55.55 52.72 Except when comparing means with the same level(s) of Var 0.4739 0.8051 d.f. 48 55.55 N 0.5804 d.f. 48 Var.N 0.8208 d.f. 48 Var.DAP 0.8051 d.f. 55.55
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Analysis of variance Variate: Leaf Area index (LAI) Source of variation d.f. s.s. m.s. v.r. F pr. Variety 1 2.2359 2.2359 18.45 0.003 Nitrogen 2 0.7696 0.3848 3.18 0.097 DAP 4 12.9037 3.2259 26.62 <.001 Variety.Nitrogen 2 0.0229 0.0115 0.09 0.911 Variety.DAP 4 0.6266 0.1567 1.29 0.350 Nitrogen.DAP 8 0.3502 0.0438 0.36 0.914 Residual 8 0.9695 0.1212 Total 29 17.8785 Tables of means Variate: LAI Grand mean 1.600 Variety 1 2 1.327 1.873 Nitrogen 1 2 3 1.451 1.822 1.526 DAP 35 70 105 140 175 0.562 1.285 1.802 2.543 1.807 Variety Nitrogen 1 2 3 1 1.156 1.588 1.236 2 1.746 2.056 1.816 Variety DAP 35 70 105 140 175 1 0.543 1.007 1.370 2.153 1.560 2 0.580 1.563 2.233 2.933 2.053 Nitrogen DAP 35 70 105 140 175 1 0.505 1.170 1.445 2.495 1.640 2 0.615 1.430 2.210 2.835 2.020 3 0.565 1.255 1.750 2.300 1.760 Standard errors of means Table Variety Nitrogen DAP Variety Nitrogen rep. 15 10 6 5 d.f. 8 8 8 8
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e.s.e. 0.0899 0.1101 0.1421 0.1557 Table Variety Nitrogen DAP DAP rep. 3 2 d.f. 8 8 e.s.e. 0.2010 0.2462 Analysis of variance Variate: LDM Source of variation d.f. s.s. m.s. v.r. F pr. Block stratum 2 22.1 11.1 0.04 Block.Cultivar stratum Cultivar 1 1719.7 1719.7 6.50 0.125 Residual 2 528.9 264.5 1.00 Block.Cultivar.Nrates stratum Nrates 2 224.7 112.3 0.42 0.668 Cultivar.Nrates 2 101.6 50.8 0.19 0.829 Residual 8 2115.3 264.4 1.12 Block.Cultivar.Nrates.DAP stratum DAP 4 18359.4 4589.9 19.50 <.001 Cultivar.DAP 4 907.1 226.8 0.96 0.436 Nrates.DAP 8 335.2 41.9 0.18 0.993 Cultivar.Nrates.DAP 8 529.3 66.2 0.28 0.969 Residual 48 11300.4 235.4 Total 89 36143.8 Tables of means Variate: LDM Grand mean 27.66 Cultivar Samoa 1 Samoa 2 23.29 32.03 Nrates 0 100 200 25.43 28.67 28.89 DAP 35 70 105 140 175 3.81 28.96 40.71 43.23 21.61 Cultivar Nrates 0 100 200 Samoa 1 21.02 23.02 25.84
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Samoa 2 29.85 34.32 31.94 Cultivar DAP 35 70 105 140 175 Samoa 1 2.75 18.81 36.38 38.82 19.70 Samoa 2 4.86 39.10 45.04 47.64 23.53 Nrates DAP 35 70 105 140 175 0 3.96 25.77 39.00 38.70 19.73 100 4.50 33.44 41.51 44.15 19.73 200 2.96 27.65 41.62 46.83 25.39 Cultivar Nrates DAP 35 70 105 140 175 Samoa 1 0 4.60 18.66 35.34 30.40 18.10 100 4.00 23.16 33.06 42.30 13.56 200 4.67 14.60 40.75 43.76 27.43 Samoa 2 0 6.33 32.89 42.67 47.00 21.35 100 8.00 43.73 49.96 46.01 25.89 200 3.00 40.70 42.49 49.90 23.34 Standard errors of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 e.s.e. 2.424 2.969 3.617 4.199 d.f. 2 8 48 9 Except when comparing means with the same level(s) of Cultivar 4.199 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 e.s.e. 5.177 6.341 8.967 d.f. 27.22 53.45 55.43 Except when comparing means with the same level(s) of Cultivar 5.115 8.967 d.f. 48 53.45 Nrates 6.264 d.f. 48 Cultivar.Nrates 8.859 d.f. 48 Cultivar.DAP 8.967 d.f. 53.45 Standard errors of differences of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15
83
s.e.d. 3.428 4.199 5.115 5.938 d.f. 2 8 48 9 Except when comparing means with the same level(s) of Cultivar 5.938 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 s.e.d. 7.322 8.967 12.681 d.f. 27.22 53.45 55.43 Except when comparing means with the same level(s) of Cultivar 7.233 12.681 d.f. 48 53.45 Nrates 8.859 d.f. 48 Cultivar.Nrates 12.528 d.f. 48 Cultivar.DAP 12.681 d.f. 53.45 Least significant differences of means (5% level) Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 l.s.d. 14.751 9.682 10.283 13.432 d.f. 2 8 48 9 Except when comparing means with the same level(s) of Cultivar 13.692 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 l.s.d. 15.017 17.982 25.410 d.f. 27.22 53.45 55.43 Except when comparing means with the same level(s) of Cultivar 14.543 25.430 d.f. 48 53.45 Nrates 17.811 d.f. 48 Cultivar.Nrates 25.189 d.f. 48 Cultivar.DAP 25.430 d.f. 53.45 Analysis of variance Variate: PDM
84
Source of variation d.f. s.s. m.s. v.r. F pr. Block stratum 2 645.4 322.7 0.10 Block.Cultivar stratum Cultivar 1 6964.3 6964.3 2.25 0.273 Residual 2 6195.6 3097.8 1.96 Block.Cultivar.Nrates stratum Nrates 2 7676.7 3838.3 2.43 0.150 Cultivar.Nrates 2 1016.6 508.3 0.32 0.734 Residual 8 12644.1 1580.5 1.63 Block.Cultivar.Nrates.DAP stratum DAP 4 111078.4 27769.6 28.66 <.001 Cultivar.DAP 4 4772.8 1193.2 1.23 0.310 Nrates.DAP 8 7962.2 995.3 1.03 0.429 Cultivar.Nrates.DAP 8 6880.0 860.0 0.89 0.534 Residual 48 46502.8 968.8 Total 89 212338.9 Tables of means Variate: PDM Grand mean 60.65 Cultivar Samoa 1 Samoa 2 51.85 69.45 Nrates 0 100 200 47.81 69.14 65.01 DAP 35 70 105 140 175 5.78 49.46 88.47 107.43 52.11 Cultivar Nrates 0 100 200 Samoa 1 41.24 55.59 58.73 Samoa 2 54.38 82.68 71.28 Cultivar DAP 35 70 105 140 175 Samoa 1 4.78 37.93 69.44 94.94 52.18 Samoa 2 6.78 60.99 107.50 119.91 52.05 Nrates DAP 35 70 105 140 175 0 5.67 34.35 63.60 86.05 49.37 100 6.42 52.46 117.14 121.23 48.43 200 5.25 61.58 84.68 114.99 58.53
85
Cultivar Nrates DAP 35 70 105 140 175 Samoa 1 0 6.00 17.86 65.25 65.83 52.35 100 8.00 46.55 72.34 108.38 45.75 200 6.50 72.25 70.74 110.60 58.43 Samoa 2 0 7.50 50.84 61.95 106.28 46.39 100 10.00 58.36 161.93 134.09 51.11 200 7.00 73.77 98.63 51.00 58.64 Standard errors of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 e.s.e. 8.297 7.258 7.336 11.793 d.f. 2 8 48 6.48 Except when comparing means with the same level(s) of Cultivar 10.265 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 e.s.e. 12.448 13.485 19.936 d.f. 9.51 47.62 36.09 Except when comparing means with the same level(s) of Cultivar 10.375 19.071 d.f. 48 47.62 Nrates 12.707 d.f. 48 Cultivar.Nrates 17.970 d.f. 48 Cultivar.DAP 19.071 d.f. 47.62 Standard errors of differences of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 s.e.d. 11.734 10.265 10.375 16.678 d.f. 2 8 48 6.48 Except when comparing means with the same level(s) of Cultivar 14.517 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP
86
rep. 9 6 3 s.e.d. 17.604 19.071 28.193 d.f. 9.51 47.62 36.09 Except when comparing means with the same level(s) of Cultivar 14.673 26.971 d.f. 48 47.62 Nrates 17.970 d.f. 48 Cultivar.Nrates 25.414 d.f. 48 Cultivar.DAP 26.971 d.f. 47.62 Least significant differences of means (5% level) Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 l.s.d. 50.486 23.671 20.861 40.092 d.f. 2 8 48 6.48 Except when comparing means with the same level(s) of Cultivar 33.476 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 l.s.d. 39.499 38.354 57.174 d.f. 9.51 47.62 36.09 Except when comparing means with the same level(s) of Cultivar 29.502 54.240 d.f. 48 47.62 Nrates 36.132 d.f. 48 Cultivar.Nrates 51.098 d.f. 48 Cultivar.DAP 54.240 d.f. 47.62 Analysis of variance Variate: CDM
87
Source of variation d.f. s.s. m.s. v.r. F pr. Block stratum 2 5071. 2535. 0.49 Block.Cultivar stratum Cultivar 1 17787. 17787. 3.43 0.205 Residual 2 10367. 5184. 3.53 Block.Cultivar.Nrates stratum Nrates 2 2235. 1118. 0.76 0.498 Cultivar.Nrates 2 1082. 541. 0.37 0.703 Residual 8 11740. 1467. 1.22 Block.Cultivar.Nrates.DAP stratum DAP 4 313576. 78394. 65.06 <.001 Cultivar.DAP 4 11371. 2843. 2.36 0.067 Nrates.DAP 8 1190. 149. 0.12 0.998 Cultivar.Nrates.DAP 8 1474. 184. 0.15 0.996 Residual 48 57839. 1205. Total 89 433733. Tables of means Variate: CDM Grand mean 63.65 Cultivar Samoa 1 Samoa 2 49.59 77.71 Nrates 0 100 200 56.88 68.74 65.33 DAP 35 70 105 140 175 5.19 18.73 44.65 79.35 170.32 Cultivar Nrates 0 100 200 Samoa 1 47.60 51.34 49.83 Samoa 2 66.16 86.13 80.83 Cultivar DAP 35 70 105 140 175 Samoa 1 5.83 12.36 32.25 58.98 138.54 Samoa 2 4.56 25.10 57.06 99.72 202.10 Nrates DAP 35 70 105 140 175 0 4.58 15.86 35.77 66.17 162.04 100 6.83 19.55 48.99 88.40 179.91 200 4.17 20.78 49.21 83.48 169.01
88
Cultivar Nrates DAP 35 70 105 140 175 Samoa 1 0 2.00 12.95 32.60 46.81 140.65 100 1.25 13.54 31.95 68.33 135.66 200 1.25 10.58 32.20 61.79 139.31 Samoa 2 0 2.25 18.76 38.93 85.53 183.42 100 2.50 25.57 66.02 108.48 224.17 200 2.00 30.99 66.22 105.16 198.71 Standard errors of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 e.s.e. 10.733 6.994 8.182 13.432 d.f. 2 8 48 4.54 Except when comparing means with the same level(s) of Cultivar 9.891 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 e.s.e. 14.910 14.477 22.400 d.f. 7.19 52.49 27.02 Except when comparing means with the same level(s) of Cultivar 11.571 20.473 d.f. 48 52.49 Nrates 14.171 d.f. 48 Cultivar.Nrates 20.042 d.f. 48 Cultivar.DAP 20.473 d.f. 52.49 Standard errors of differences of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 s.e.d. 15.179 9.891 11.571 18.996 d.f. 2 8 48 4.54 Except when comparing means with the same level(s) of Cultivar 13.988 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3
89
s.e.d. 21.086 20.473 31.678 d.f. 7.19 52.49 27.02 Except when comparing means with the same level(s) of Cultivar 16.364 28.954 d.f. 48 52.49 Nrates 20.042 d.f. 48 Cultivar.Nrates 28.343 d.f. 48 Cultivar.DAP 28.954 d.f. 52.49 Least significant differences of means (5% level) Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 l.s.d. 65.308 22.809 23.265 50.348 d.f. 2 8 48 4.54 Except when comparing means with the same level(s) of Cultivar 32.256 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 l.s.d. 49.595 41.074 64.996 d.f. 7.19 52.49 27.02 Except when comparing means with the same level(s) of Cultivar 32.902 58.087 d.f. 48 52.49 Nrates 40.296 d.f. 48 Cultivar.Nrates 56.987 d.f. 48 Cultivar.DAP 58.087 d.f. 52.49 Analysis of variance Variate: RDM Source of variation d.f. s.s. m.s. v.r. F pr.
90
Block stratum 2 21.10 10.55 0.23 Block.Cultivar stratum Cultivar 1 418.38 418.38 9.05 0.095 Residual 2 92.50 46.25 4.78 Block.Cultivar.Nrates stratum Nrates 2 78.49 39.25 4.06 0.061 Cultivar.Nrates 2 7.61 3.80 0.39 0.687 Residual 8 77.34 9.67 0.56 Block.Cultivar.Nrates.DAP stratum DAP 4 2594.09 648.52 37.69 <.001 Cultivar.DAP 4 577.55 144.39 8.39 <.001 Nrates.DAP 8 116.33 14.54 0.85 0.568 Cultivar.Nrates.DAP 8 19.59 2.45 0.14 0.997 Residual 48 825.96 17.21 Total 89 4828.93 Tables of means Variate: RDM Grand mean 6.66 Cultivar Samoa 1 Samoa 2 4.50 8.81 Nrates 0 100 200 6.03 7.98 5.96 DAP 35 70 105 140 175 0.67 4.57 7.39 16.51 4.14 Cultivar Nrates 0 100 200 Samoa 1 3.96 5.43 4.11 Samoa 2 8.10 10.52 7.81 Cultivar DAP 35 70 105 140 175 Samoa 1 0.56 4.04 5.30 9.46 3.14 Samoa 2 0.78 5.09 9.49 23.55 5.15 Nrates DAP 35 70 105 140 175 0 0.71 4.25 6.48 13.97 4.74 100 0.75 5.34 8.92 20.74 4.11 200 0.54 4.11 6.78 14.80 3.57 Cultivar Nrates DAP 35 70 105 140 175
91
Samoa 1 0 0.58 4.04 4.68 6.02 4.47 100 0.42 4.88 6.03 13.64 2.18 200 0.67 3.20 5.20 8.72 2.76 Samoa 2 0 0.83 4.45 8.28 21.92 5.02 100 1.08 5.80 11.82 27.85 6.05 200 0.42 5.01 8.36 20.88 4.38 Standard errors of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 e.s.e. 1.014 0.568 0.978 1.207 d.f. 2 8 48 3.85 Except when comparing means with the same level(s) of Cultivar 0.803 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 e.s.e. 1.599 1.618 2.459 d.f. 11.34 55.82 36.93 Except when comparing means with the same level(s) of Cultivar 1.383 2.288 d.f. 48 55.82 Nrates 1.693 d.f. 48 Cultivar.Nrates 2.395 d.f. 48 Cultivar.DAP 2.288 d.f. 55.82 Standard errors of differences of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 s.e.d. 1.434 0.803 1.383 1.707 d.f. 2 8 48 3.85 Except when comparing means with the same level(s) of Cultivar 1.135 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 s.e.d. 2.262 2.288 3.477
92
d.f. 11.34 55.82 36.93 Except when comparing means with the same level(s) of Cultivar 1.955 3.235 d.f. 48 55.82 Nrates 2.395 d.f. 48 Cultivar.Nrates 3.387 d.f. 48 Cultivar.DAP 3.235 d.f. 55.82 Least significant differences of means (5% level) Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 l.s.d. 6.169 1.851 2.780 4.812 d.f. 2 8 48 3.85 Except when comparing means with the same level(s) of Cultivar 2.618 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 l.s.d. 4.960 4.583 7.046 d.f. 11.34 55.82 36.93 Except when comparing means with the same level(s) of Cultivar 3.932 6.481 d.f. 48 55.82 Nrates 4.815 d.f. 48 Cultivar.Nrates 6.810 d.f. 48 Cultivar.DAP 6.481 d.f. 55.82
Analysis of variance Variate: SDM Source of variation d.f. s.s. m.s. v.r. F pr. Block stratum 2 3758. 1879. 0.41
93
Block.Cultivar stratum Cultivar 1 11059. 11059. 2.43 0.260 Residual 2 9112. 4556. 2.32 Block.Cultivar.Nrates stratum Nrates 2 3976. 1988. 1.01 0.405 Cultivar.Nrates 2 3787. 1894. 0.97 0.421 Residual 8 15690. 1961. 1.13 Block.Cultivar.Nrates.DAP stratum DAP 4 132007. 33002. 19.08 <.001 Cultivar.DAP 4 6272. 1568. 0.91 0.468 Nrates.DAP 8 6483. 810. 0.47 0.872 Cultivar.Nrates.DAP 8 11771. 1471. 0.85 0.564 Residual 48 83011. 1729. Total 89 286925. Tables of means Variate: SDM Grand mean 42.39 Cultivar Samoa 1 Samoa 2 31.31 53.48 Nrates 0 100 200 34.75 50.95 41.47 DAP 35 70 105 140 175 0.00 8.84 27.87 80.28 94.97 Cultivar Nrates 0 100 200 Samoa 1 28.17 30.70 35.06 Samoa 2 41.34 71.21 47.88 Cultivar DAP 35 70 105 140 175 Samoa 1 0.00 1.96 15.99 54.80 83.79 Samoa 2 0.00 15.72 39.75 105.76 106.16 Nrates DAP 35 70 105 140 175 0 0.00 7.77 28.03 68.40 69.56 100 0.00 8.55 28.83 96.80 120.60 200 0.00 10.20 26.76 75.64 94.76 Cultivar Nrates DAP 35 70 105 140 175 Samoa 1 0 0.00 1.75 12.75 43.65 82.69 100 0.00 4.25 21.09 54.91 73.34
94
200 0.00 0.00 14.12 65.83 95.34 Samoa 2 0 0.00 13.80 43.29 93.15 56.44 100 0.00 12.95 36.57 138.69 167.85 200 0.00 20.41 39.39 85.44 94.18 Standard errors of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 e.s.e. 10.062 8.085 9.802 13.726 d.f. 2 8 48 5.84 Except when comparing means with the same level(s) of Cultivar 11.435 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 e.s.e. 15.968 17.203 25.487 d.f. 11.57 53.35 40.16 Except when comparing means with the same level(s) of Cultivar 13.862 24.329 d.f. 48 53.35 Nrates 16.977 d.f. 48 Cultivar.Nrates 24.010 d.f. 48 Cultivar.DAP 24.329 d.f. 53.35 Standard errors of differences of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 s.e.d. 14.230 11.435 13.862 19.412 d.f. 2 8 48 5.84 Except when comparing means with the same level(s) of Cultivar 16.171 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 s.e.d. 22.582 24.329 36.044 d.f. 11.57 53.35 40.16 Except when comparing means with the same level(s) of Cultivar 19.604 34.407 d.f. 48 53.35
95
Nrates 24.010 d.f. 48 Cultivar.Nrates 33.955 d.f. 48 Cultivar.DAP 34.407 d.f. 53.35 Least significant differences of means (5% level) Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 l.s.d. 61.226 26.368 27.871 47.809 d.f. 2 8 48 5.84 Except when comparing means with the same level(s) of Cultivar 37.290 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 l.s.d. 49.404 48.791 72.838 d.f. 11.57 53.35 40.16 Except when comparing means with the same level(s) of Cultivar 39.416 69.001 d.f. 48 53.35 Nrates 48.275 d.f. 48 Cultivar.Nrates 68.271 d.f. 48 Cultivar.DAP 69.001 d.f. 53.35 Analysis of variance Variate: TDM Source of variation d.f. s.s. m.s. v.r. F pr. Block stratum 2 22407. 11204. 0.28
96
Block.Cultivar stratum Cultivar 1 147382. 147382. 3.72 0.194 Residual 2 79245. 39622. 2.54 Block.Cultivar.Nrates stratum Nrates 2 46095. 23047. 1.48 0.284 Cultivar.Nrates 2 16383. 8191. 0.53 0.610 Residual 8 124761. 15595. 2.22 Block.Cultivar.Nrates.DAP stratum DAP 4 1416769. 354192. 50.46 <.001 Cultivar.DAP 4 45292. 11323. 1.61 0.186 Nrates.DAP 8 18180. 2273. 0.32 0.953 Cultivar.Nrates.DAP 8 30847. 3856. 0.55 0.813 Residual 48 336892. 7019. Total 89 2284253. Tables of means Variate: TDM Grand mean 201.01 Cultivar Samoa 1 Samoa 2 160.54 241.48 Nrates 0 100 200 170.90 225.47 206.65 DAP 35 70 105 140 175 15.44 110.55 209.10 326.79 343.16 Cultivar Nrates 0 100 200 Samoa 1 141.99 166.08 173.57 Samoa 2 199.82 284.87 239.74 Cultivar DAP 35 70 105 140 175 Samoa 1 13.92 75.10 159.37 256.99 297.34 Samoa 2 16.97 146.01 258.84 396.59 388.98 Nrates DAP 35 70 105 140 175 0 14.92 88.00 172.87 273.30 305.44 100 18.50 119.35 245.39 371.34 372.78 200 12.92 124.32 209.04 335.73 351.26 Cultivar Nrates DAP 35 70 105 140 175 Samoa 1 0 13.15 55.25 150.62 192.72 298.33 100 13.68 92.28 164.47 287.70 270.50
97
200 13.08 100.55 163.00 290.50 323.27 Samoa 2 0 16.90 120.58 195.12 353.88 312.63 100 21.56 146.05 326.31 455.12 475.07 200 12.43 170.95 255.08 312.53 379.25 Standard errors of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 e.s.e. 29.673 22.800 19.746 39.669 d.f. 2 8 48 5.53 Except when comparing means with the same level(s) of Cultivar 32.244 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 e.s.e. 38.786 38.153 58.696 d.f. 5.72 40.73 22.80 Except when comparing means with the same level(s) of Cultivar 27.926 53.956 d.f. 48 40.73 Nrates 34.202 d.f. 48 Cultivar.Nrates 48.369 d.f. 48 Cultivar.DAP 53.956 d.f. 40.73 Standard errors of differences of means Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 s.e.d. 41.964 32.244 27.926 56.100 d.f. 2 8 48 5.53 Except when comparing means with the same level(s) of Cultivar 45.600 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 s.e.d. 54.852 53.956 83.009 d.f. 5.72 40.73 22.80 Except when comparing means with the same level(s) of
98
Cultivar 39.493 76.306 d.f. 48 40.73 Nrates 48.369 d.f. 48 Cultivar.Nrates 68.404 d.f. 48 Cultivar.DAP 76.306 d.f. 40.73 Least significant differences of means (5% level) Table Cultivar Nrates DAP Cultivar Nrates rep. 45 30 18 15 l.s.d. 180.558 74.355 56.148 140.142 d.f. 2 8 48 5.53 Except when comparing means with the same level(s) of Cultivar 105.153 d.f. 8 Table Cultivar Nrates Cultivar DAP DAP Nrates DAP rep. 9 6 3 l.s.d. 135.835 108.989 171.802 d.f. 5.72 40.73 22.80 Except when comparing means with the same level(s) of Cultivar 79.406 154.134 d.f. 48 40.73 Nrates 97.252 d.f. 48 Cultivar.Nrates 137.535 d.f. 48 Cultivar.DAP 154.134 d.f. 40.73
91
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56
7 0.
16
2.00
0.
03
0.43
0.
00
0 12
.43
Sam
oa 2
70
0
0.27
32
.88
0.42
50
.75
0.16
18
.75
0.04
4.
45
0.11
13
.75
120.
58
Sam
oa 2
10
0 0.
30
43.5
0 0.
40
58.2
5 0.
17
25.5
0 0.
04
5.80
0.
09
13
146.
05
Sam
oa 2
20
0 0.
24
40.7
0 0.
43
73.7
5 0.
18
31.0
0 0.
03
5.00
0.
12
20.5
17
0.95
Sam
oa 2
10
5 0
0.22
42
.50
0.32
62
0.
20
39.0
0 0.
04
8.28
0.
22
43.2
5 19
5.03
91
Sam
oa 2
10
0 0.
15
49.9
5 0.
50
162
0.20
66
.00
0.04
11
.83
0.11
36
.5
326.
28
Sam
oa 2
20
0 0.
17
42.5
0 0.
39
98.7
5 0.
26
66.2
5 0.
03
8.35
0.
15
39.5
25
5.35
Sam
oa 2
14
0 0
0.13
47
.00
0.30
10
6.25
0.
24
85.5
0 0.
06
21.9
3 0.
26
93.2
5 35
3.93
Sam
oa 2
10
0 0.
10
46.0
0 0.
29
134
0.24
10
8.50
0.
06
27.8
5 0.
30
138.
75
455.
10
Sam
oa 2
20
0 0.
16
49.9
0 0.
16
51
0.34
10
5.25
0.
07
20.8
8 0.
27
85.5
31
2.53
Sam
oa 2
17
5 0
0.07
21
.35
0.15
46
.5
0.59
18
3.50
0.
02
5.03
0.
18
56.5
31
2.88
Sam
oa 2
10
0 0.
05
25.9
0 0.
11
51
0.47
22
4.25
0.
01
6.05
0.
35
167.
75
474.
95
Sam
oa 2
20
0 0.
06
23.3
5 0.
15
58.7
5 0.
52
198.
75
0.01
4.
38
0.25
94
.25
379.
48
LR (L
eaf r
atio
)
DM
(Dry
mat
ter)