American Journal of Plant Sciences, 2013, 4, 122-130
Published Online December 2013 (http://www.scirp.org/journal/ajps)
http://dx.doi.org/10.4236/ajps.2013.4.12A3015
Open Access AJPS
Yield and Yield Components of Bread Wheat as Influenced
by Water Stress, Sowing Date and Cultivar in Sokoto,
Sudan Savannah, Nigeria
Mohammed Bello Sokoto1*, Agit Singh2
1Department of Crop Science, Faculty of Agriculture, Usmanu Danfodiyo University, Sokoto, Nigeria; 2School of Biosciences, Fac-
ulty of Science, The University of Nottingham, Malaysia Campus, Jalan Broga, Semenyih, Selangor, Malaysia.
Received October 7th, 2013; revised November 26th, 2013; accepted December 16th, 2013
Copyright © 2013 Mohammed Bello Sokoto, Agit Singh. This is an open access article distributed under the Creative Commons Attribu-
tion License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Field experiments were conducted during 2009/10 and 2010/2011 dry seasons at the Fadama Teaching and Research
Farm of the Usmanu Danfodiyo University, Sokoto, in the Sudan Savanna ecological zone of Nigeria (latitude 13˚01'N;
longitude 5˚15'E, altitude of 350 m above sea level) to study the effect of water stress, sowing date and cultivar on yield
and yield components of wheat (Triticum aestivum L.). The treatments consisted of factorial combination of water stress
at three critical growth stages which was imposed by withholding water at tillering, flowering, grain filling and control
(no stress), four sowing dates (21st November, 5th December, 19th December and 2nd January) and two bread wheat cul-
tivar (Star 11 TR 77173/SLM and Kuaz/Weaver), laid out in a split-plot design with three replications. Water stress and
date of sowing were assigned to the main-plot, while variety was assigned to the sub-plots. Result revealed that water
stress at tillering significantly reduced spike length and grains per spike. Whereas, water stress at flowering and grain
filling significantly reduced 1000-grain weight, grain yield and harvest index. Results also indicated significant (P <
0.05) effect of sowing date on length of spike, spikelets per spike, grains per spike and grain yield. Early sown wheat
significantly differed from the late sown wheat in all parameters measured. Yield and yield components decreased with
delay in sowing date and it was highest at 21st November and 5th December and lowest at 19th December and 2nd Janu-
ary, therefore wheat should be sown in November or at least first week of December in this area and other area with
similar climate. Variety had significant effect on spike per m−2, grain yield and harvest index. Water stress at flowering
and grain filling should be avoided as they are the most critical growth stages in yield determination in wheat, because
plants cannot recover, while delay in sowing resulted in reduction in yield and yield components. Star II TR
77173/SLM is therefore recommended for the area.
Keywords: Yield; Yield Components; Bread Wheat; Water Stress; Sowing Date Cultivar; Sudan Savanna
1. Introduction
Wheat (Triticum aestivum L.) belongs to the tribe Triti-
ceae which is one of the largest and most important tribes
in the Poaceae family [1]. It is grown on 200 million
hectares with an average total production of 600 million
metric tons. Global average yield is around 2.7 t·ha−1
with high variability among countries and regions. The
highest average yields are obtained in Western Europe,
with more than 8 t·ha−1, in contrast to less than 1 t·ha−1 in
countries in Central/West Asia and North Africa [2]. Ni-
gerian production currently stands at 100,000 tonnes
from 95,000 hectares with an average yield of 1.05 t·ha−1
[3]; this is far below that of Germany (7.9 tons·ha−1),
France (6.6 tons·ha−1) and Egypt (6.4 tons·ha−1) [4].
Wheat contributes about 60% of daily protein require-
ment and more calories to world diet than any other food
crop [5].
Nigeria is currently the second largest export destina-
tion for USA wheat [3,6] reported that food security in
the world is challenged by increasing food demand and
threatened by declining water availability. Wheat pro-
duction has been shown to be limited by a number of
factors such as moisture stress [7,8], variety and weed [9];
soil fertility and date of sowing [8,10] observed that con-
*Corresponding author.

Yield and Yield Components of Bread Wheat as Influenced by Water Stress,
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123
tinual heat stress affects approximately 7 million hectares
of wheat in developing countries, whereas terminal heat
stress is a problem in 40% of the temperate environments
that encompass 36 million hectares.
Wheat is an important cereal crop and serves as a sta-
ple food in many countries of the world [7]. With human
population expected to reach 8.3 billion by 2025, coupled
with continuous deterioration and losses of agricultural
lands, it has become imperative to have crop varieties of
higher yielding and good quality and this ought to be
achieved to feed the billions of human population. [8,11]
observed that supply of irrigation water at different stag-
es of plant growth plays a vital roles in boosting yield per
unit area; the authors further observed that optimum
sowing date plays an important role on yield of wheat.
Currently, some newly developed wheat varieties have
been introduced into the country from CIMMYT, Mex-
ico. These varieties need to be evaluated for their re-
sponse to local conditions, particularly heat tolerance
[12]. This is important in the Sudan savanna where high
temperatures at the end of the dry season which coincides
with grain filling stage of wheat are common features
and impediment to good wheat crop performance. [13]
observed that higher productivity of wheat in USA was
due to more favorable environmental condition which
includes temperature and moisture.
The objectives of the study are to determine the effect
of water stress at critical growth stages on the productiv-
ity of two wheat varieties, so that farmers could save
irrigation (which is expensive) with the knowledge of
critical growth stages, determine the effect of sowing
date on yield and yield components of two wheat culti-
vars to enable the farmers to know the optimum sowing
date for the newly introduced cultivars and determine the
most suitable wheat cultivar for farmers in Sokoto and
other areas with similar conditions.
2. Materials and Methods
The trials were conducted during the 2009/2010 and
2010/2011 dry seasons at the Fadama Teaching and Re-
search Farm, Usmanu Danfodiyo University, Sokoto,
(Latitude 13˚01'N. longitude 15˚13'E) at Kwalkwalawa
village in Sokoto. The farm is located within the Sudan
Savanna Zone of Nigeria [14]. The area has a long dry
season that is characterized by cool dry air during har-
mattan from November to February and hot dry air dur-
ing hot season from March to May [15]. The soil is hy-
dromorphic that is seasonally flooded during rainy sea-
son. The area was previously used for the cultivation of
vegetables and cereals crops. Prior to sowing, soil sam-
ples were collected from nine randomly selected points
within the experimental site at 0 - 30 cm depth using soil
auger. The samples were bulked to form a composite
sample and sub-samples about 200 g were collected us-
ing coning and quatering method. The samples were air-
dried, grounded, sieved and analyzed for physical and
chemical properties.
The treatments consisted of factorial combinations of
water stress at three critical growth stages which was
imposed by withholding water at tillering, flowering,
grain filling and control (no stress), four sowing dates
(21st November, 5th December, 19th December and 2nd
January) and two heat tolerant wheat varieties (Star 11
TR 77173/SLM and Kuaz/Weaver), laid out in a split
plot design with three replications. Water stress and date
of sowing were assigned to the main-plot, while variety
was assigned to sub-plots.
The land was cleared, ploughed, harrowed, leveled,
which was followed by construction of basins and water
channels. Gross plot size was 3 m × 3 m (9 m2) while the
net plot was (4.5 m2). One meter (1 m) lee-way was left
between blocks and 0.5 m between plots. The seeds were
treated with Apron star 42 WS (20% w/w thiamethoxam,
20% w/w metalaxyl-M and 2% w/w difenoconazole) at
the rate of 10 g per 4 kg of seed before sowing. The seeds
were sown by hand drilling at 20 cm intra-row spacing at 2
- 3 cm depth and at the rate of 120 kg·ha−1. The date of
sowing was as prescribed by the treatments. The method
of irrigation used was check basin irrigation; water was
applied to soil saturation at 5 days interval. Weeds were
controlled manually with hoe at 3 and 6 WAS to ensure
weed free plots. Fertilizer was broadcasted at the rec-
ommended rate of 120, 60 and 60 kg N, P2O5 and K2O
per ha−1, respectively. Half of nitrogen and full dose of
phosphorous and potassium was worked in to the soil
during seedbed preparation using NPK 15:15:15: while,
the second dose of 60 kg N ha−1 was applied prior to til-
lering using urea (46% N) as source of nitrogen. Birds
were controlled by scaring while rodents were controlled
by using baits and traps. No disease out break was recorded.
The crop was manually harvested from the net plot at
physiological maturity using sickles when 50% of the
peduncles had turned brown. The plants were cut at ground
level and sun dried for a period of 4 days. The spikes
were beaten out with sticks to expose the grain, which
was winnowed in open air with the help of wind current.
Data was collected on length of spike, number of spikelets
per spike, number of grains per spike and grain yield.
The data collected were subjected to analysis of vari-
ance (ANOVA) using SAS [16] computer package.
Duncan’s New Multiple Range Test (DNMRT) was used
for means separation.
3. Results and Discussion
3.1. Physical and Chemical Properties of
the Experimental Site
The soil of the experimental area was sandy loam using
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Yield and Yield Components of Bread Wheat as Influenced by Water Stress,
Sowing Date and Cultivar in Sokoto, Sudan Savannah, Nigeria
124
the USDA textural triangle, slightly acidic, very low N
content, low organic carbon content extremely low
available P content; low Ca values, medium Mg, high K,
moderate Na and low CEC. Meteorological data of the
experimental site showed that the relative humidity
ranged from 26% - 39% in the dry season. Minimum
temperature ranged between 18˚C to 29˚C and Maximum
temperature ranged from 30˚C to 42˚C from November
to April and, wind speed ranged between 1.9 to 5 m/s
(Sokoto Energy Research Center) [17]. The meteoro-
logical data is a typical of Sudan Savannah as reported
by Davis [15] and [18] who reported relative humidity of
21 - 47 during the harmattan and temperature ranged of
17 - 40 from November to April.
3.2. Length of Spike
The effect of water stress and sowing date on length of
spike of two bread wheat varieties in 2009/10 and
2010/11 dry seasons and combined is presented in Tab le
1. In both seasons and combined the result indicated that
water stress at tillering resulted in shorter spikes than
water stress at flowering, grain filling or the no stress
control which are statistically (p < 0.05) similar. The
shorter spikes observed at stress at tillering could be as a
result of water stress imposed at that stage which resulted
to shorter plants. In wheat there is correlation between
incoming radiation and photosynthates available for
spike growth [19]. Water stress retards photosynthasis
and translocation of photosynthates to spike growth. [20]
also observed reduction of spike length under water
stress.
The effect of sowing date on length of spike is pre-
sented in Table 1. In both seasons and combined, length
of spike decreased with delay in sowing from 21st No-
vember to 2nd January. Plants sown on 19th December
and 2nd January are statistically similar with shorter spike
than plants sown on 21st November and 5th December
which were statistically (p < 0.05) similar with longer
spike. Decreased in spike length observed at the two late
sowing dates could be as a result of delay in sowing in
those treatments. In late sowing small heads are formed
due to shortened growing period, the result is not in
agreement with that of [21] who reported that spike
length is not affected by sowing date.
The effect of variety on length of spike is presented in
Table 1. In both seasons and combined, variety had no
significant difference in length of spike.
3.3. Number of Spikelets per Spike
The effect of water stress and sowing date on spikelets
per spike of two bread wheat varieties in 2009/10 and
2010/11 dry seasons and combined is presented in Tab le
2. In both seasons and combined, the result indicated that
Table 1. Effects of water stress, sowing date and variety on
length of spike of bread wheat in 2009/10, 2010/11 dry sea-
sons and combined at Sokoto.
Length of spike (cm)
Treatment
2009/10 2010/11 Combined
Water stress
Tillering 11.44b 14.20b 12.82b
Flowering 12.02a 15.03a 13.52a
Grain filling 12.12a 15.12a 13.62a
Control 12.17a 15.10a 13.67a
Significance * * *
SE± 0.049 0.149 0.094
Sowing date
21st November 12.57a 15.47a 14.02a
5th December 12.50a 15.46a 13.98a
19th December 11.47b 14.41b 12.94b
2nd January 11.21b 14.18b 12.70b
Significance * * *
SE± 0.106 0.097 0.101
Variety
Star II TR77173/SLM11.97 14.92 13.45
Kauz/Weaver 11.90 14.84 13.37
Significance Ns Ns Ns
SE± 0.096 0.098 0.051
Interaction
S X D Ns * *
S X V Ns Ns Ns
D X V Ns * *
S X D X V Ns Ns Ns
Means in a column and treatment group followed by same letters are not
significantly different using DNMRT at 5% level. NS = Not significant, *=
significant at 5% level.
water stress at tillering and flowering resulted in fewer
number of spikelets per spike than water stress at grain
filling or the no stress control which are statistically sim-
ilar with higher number of spikelets per spike. The fewer
number of spikelets per spike observed could be as a
result of water stress imposed at tillering and flowering,
due to fewer spikelets primordial being formed during
tillering or may be attributed to floret death at the termi-
nal and basal end of the spike during stem extension.
This finding is in line with that of [20] reported de-
creased in spikelets per spike as a result of water stress.
The effect of sowing date on number of spikelets per
spike is presented in Tab le 2. In both seasons and com-
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Yield and Yield Components of Bread Wheat as Influenced by Water Stress,
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125
Table 2. Effects of water stress, sowing date and variety on
number of spikelets per spike of bread wheat in 2009/10
and 2010/11 dry seasons and combined at Sokoto.
Number of spikelets per spike
Treatment
2009/10 2010/11 Combined
Water stress
Tillering 30.11b 31.51b 30.81b
Flowering 31.36b 33.65b 32.50b
Grain filling 35.76a 37.91a 36.84a
Control 38.59a 40.75a 39.67a
Significance * * *
SE± 1.004 1.175 1.077
Sowing date
21st November 42.34a 44.50a 43.42a
5th December 43.36a 45.54a 44.45a
19th December 26.73b 28.57b 27.65b
2nd January 23.38b 25.22b 24.30b
Significance * * *
SE± 3.092 3.229 3.160
Variety
Star II TR77173/SLM 34.36 36.35 35.35a
Kauz/Weaver 33.55 35.56 34.55b
Significance Ns Ns *
SE± 0.476 0.477 0.244
Interaction
S X D Ns * *
S X V Ns * *
D X V Ns * *
S X D X V Ns Ns Ns
Means in a column and treatment group followed by same letters are not
significantly different using DNMRT at 5% level. NS = Not significant, *=
significant at 5% level.
bined, spikelets per spike decreased with delay in sowing
from 21st November to 2nd January. Plants sown on 19th
December and 2nd January are statistically (p < 0.05)
similar with fewer spikelets per spike than plants sown
on 21st November and 5th December which were statisti-
cally similar with higher spikelets per spike. Decrease in
number of spikelets per spike could be as a result of de-
lay in sowing in late sown plants, couple with higher
temperature experienced in the month of March and
April, photosynthesis had a broad temperature optimum
from 20˚C to 30˚C with photosynthesis and translocation
declining rapidly at temperatures above 30˚C [22]. [23]
observed that delayed sowing decreased the number of
spikelets per spike.
The effect of variety on number of spikelets per spike
is not significant in both seasons (Table 2). However, in
the combined analysis Star II TR 77173/SLM showed
higher number of spikelets per spike than Kauz/Weaver.
Significant varietal differences indicate that cultivars
responded differently.
3.4. Number of Grains per Spike
The effect of water stress and sowing date on number of
grains per spike of two bread wheat varieties in 2009/10
and 2010/11 dry seasons and combined is presented in
Table 3. In 2010/11 dry season and combined the result
Table 3. Effects of water stress, sowing date and variety on
number of grains per spike of bread wheat in 2009/10,
2010/11 dry seasons and combined at Sokoto.
Number of grains per spike
Treatment
2009/10 2010/11 Combined
Water stress
Tillering 32.06 39.89a 35.98ab
Flowering 32.22 32.37b 32.29b
Grain filling 34.79 41.40a 38.10a
Control 35.76 39.65a 37.70a
Significance Ns * *
SE± 1.729 0.970 1.298
Sowing date
21st November 37.51 39.50a 38.51a
5th December 36.63 39.78a 38.21ab
19th December 31.22 35.50b 33.36b
2nd January 29.47 35.51b 32.49b
Significance Ns * *
SE± 2.310 1.008 1.430
Variety
Star II TR77173/SLM34.27 38.83 36.55
Kauz/Weaver 33.15 37.83 35.49
Significance Ns Ns Ns
SE± 0.734 0.595 0.535
Interaction
S X D Ns * *
S X V Ns * *
D X V Ns * *
S X D X V Ns Ns Ns
Means in a column and treatment group followed by same letters are not
significantly different using DNMRT at 5% level. NS = Not significant, *=
significant at 5% level.
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Yield and Yield Components of Bread Wheat as Influenced by Water Stress,
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indicated that water stress at flowering resulted in fewer
number of grains per spike than water stress at tillering,
grain filling or the no stress control which are statistically
(p < 0.05) similar. However in 2009/10 dry season water
stress had no effect on number of grains per spike. The
fewer number of grains per spike observed in 2010/11
dry season could be as a result of water stress at flower-
ing which could affect pollen formation and sterility.
Because number of flowers and grains decrease with
water stress due to decrease in photosynthesis and trans-
location. [24] observed that pollen formation and fertili-
zation can be seriously affected under water stress.
The effect of sowing date on number of grains per
spike is presented in Tab le 3. In 2010/11 dry season and
combined, number of grains per spike decreased with
delay. Plants sown on 19th December and 2nd January are
statistically similar with fewer number of grains per
spike than plants sown on 21st November and 5th De-
cember which were statistically (p < 0.05) similar with
higher number of grains per spike. In 2009/10 water
stress did not affect number of grains per spike. De-
creased in number of grains per spike at the two late
sown plants could be as a result short growing season,
high temperature and inappropriate prevailing weather
condition during the grain filling period in late planted
crops. [25] reported that early planting resulted in maxi-
mum yield of grains per spike.
3.5. Grain Yield
The effect of water stress and sowing date on grain yield
of two bread wheat varieties in 2009/10 and 2010/11 dry
seasons and combined is presented in Table 4. Water
Table 4. Effects of water stress, sowing date and variety on grain yield of bread wheat in 2009/10, 2010/11 dry seasons and
combined at Sokoto.
Grain yield (t·ha−1)
Treatment
2009/10 2010/11 Combined % Yield decrease in combined
Water stress
Tillering 2.27b 3.80a 3.03a 16.50
Flowering 1.73c 3.06b 2.40b 34.00
Grain filling 2.26b 3.20b 2.73b 25.00
Control 2.97a 4.30a 3.63a
Significance * * *
SE± 0.095 0.268 0.243
Sowing date
21st November 3.38a 4.62a 4.00a
5th December 2.75a 3.71b 3.23b 19.25
19th December 1.48b 3.31b 2.39c 40.25
2nd January 1.52b 3.16b 2.34c 41.50
Significance * * *
SE± 0.188 0.180 0.144
Variety
Star II TR77173/SLM 2.60a 4.10a 3.35a
Kauz/Weaver 1.96b 3.30b 2.63b
Significance * * *
SE± 0.074 0.145 0.098
Interaction
S X D * * *
S X V Ns * *
D X V * * *
S X D X V Ns Ns Ns
Means in a column and treatment group followed by same letters are not significantly different using DNMRT at 5% level. NS = Not significant, *= significant
at 5% level.

Yield and Yield Components of Bread Wheat as Influenced by Water Stress,
Sowing Date and Cultivar in Sokoto, Sudan Savannah, Nigeria
127
stress resulted to significant (p < 0.05) reduction in grain
yield. In 2009/10 dry season the highest grain yield was
obtained from control (the unstressed) and the lowest
grain yield was from water stress at flowering. In 2010/
11 dry season and combined water stress at flowering
and grain filling resulted to significant reduction in grain
yield. The differences between 2009/10 dry season and
2010/11 dry season in terms of grain yield may be as a
result of relatively higher fertility status of the experi-
mental area in 2010/11 dry season, better environmental
conditions particularly relatively lower temperature and
longer grain filling period in 2010/11 dry season. The
grain filling period in 2009/10 dry season was as fallows:
21st November (24 days), 5th December (21 days), 19th
December (16 days) and 2nd January (16 days). In 2010/
11 grain filling period was longer with 21st November
having 32 days, 5th December (30 days), 19th December
(30 days) and 2nd January (23 days), the longer the grain
filling period the longer the assimilate production and
transfer. Similarly relatively higher LAI, NAR, CGR,
and 1000-grain weight in 2010/11 dry season as com-
pared to 2009/10 dry season could be responsible for the
variation.
Yield reduction due to water stress could be as a result
of reduction in photosynthesis and translocation resulting
to decrease in spikelets per spike, grain per spike and
1000-grain weight. In the combined analysis yield reduc-
tion of 16.50%, 34.00% and 25.00% was recorded as a
result of water stress at tillering, flowering and grain fill-
ing respectively.
There was a linear relationship between available wa-
ter and yield, where reduction in available water limits
evapotranspiration and consequently reduced yield, as
reported by several researchers [26]. Yield enhancement
due to irrigation was associated to significant increases in
number of tillers and spikes per m−2, number of grain per
spike and thousand kernel weights. This finding is simi-
lar to that of [7] in Pakistan who observed that irrigation
is a component of production which significantly affect
yield of wheat. Flowering period is reported to be the
most sensitive to water deficit, because pollen formation
and fertilization can be seriously affected under heavy
water stress resulting to reduction in yield largely re-
sulted from the reduction in fertile panicle number and
filled grain percentage. The loss in yield due to water
deficits during the flowering period cannot be recovered
by providing adequate water supply during the later
growth stage [24].
The effect of sowing date on grain yield is presented in
Table 4. In both seasons and combined, grain yield de-
creased with delay in sowing from 21st November to 2nd
January. Plants sown on 19th December and 2nd January
are statistically (p < 0.05) similar with lower grain yield
than plants sown on 21st November and 5th December
which were statistically similar with higher grain yield in
2009/10 dry season. In 2010/11 dry season and combined
grain yield decreased with delay in sowing from 21st
November to 2nd January (Tabl e 4). All phases of plant
growth, tillering, jointing, flowering, grain filling and
yield components such as spike length, spikelets per
spike, number of grain per spike and 1000-grain weight
were adversely affected by delay in sowing and thus
grain yield. In the combined analysis yield reduction of
19.25%, 40.25% and 41.50% was recorded as a result of
delay in sowing from 21st November to 5th December,
19th December and 2nd January respectively. Grain yield
varied significantly during the two years of experimenta-
tion grain yield in 2010/11 was higher than the previous
year. The yield difference between years might be attrib-
uted to variable temperature, leading to better leaf area
duration, average crop growth rate and long grain filling
period during 2nd year of experimentation, which is simi-
lar to the finding of [5,27] observed that the duration of
grain filling in cereals (wheat) is determined by tem-
perature. [28] reported that an increase in 10˚C can cause
decrease of 4 mg in grain weight. [29] observed that the
penalty in terms of crop yield associated with delayed
planting is in the order of 1 percent yield loss per day.
The effect of variety on grain yield is presented in Ta-
ble 4. In both seasons and combined Star II TR 77173
differed from Kauz/Weaver with higher grain yield. This
could be as results of better LAI, NAR, CGR and yield
component exhibited by Star II TR 77173. The different
responses of wheat varieties in respect of the yield and
yield components examined could be due to their varied
genetic composition and adaptation to the soil and cli-
matic conditions [30]. Similarly previous studies have
indicated that there were significant differences in grain
yield among wheat varieties [31].
The interaction between water stress and sowing date
on grain yield in 2009/10, 2010/11 dry seasons and com-
bined indicated that delay in sowing irrespective of water
stress condition decreased grain yield. Regardless of
sowing date water stress at flowering and grain filling
resulted to decrease in grain yield (Table 5). The loss in
yield due to water deficits during the flowering period
cannot be recovered by providing adequate water supply
during the later growth stage [24]. The grain yield attrib-
utes were increased to maximum under normal irrigation,
but reduced significantly under water stress [32].
The interaction between water stress and variety on
grain yield in 2010/11 and combined is presented in Ta-
ble 6. The result indicated that water stress at flowering
and grain filling resulted to lower grain yield. Regardless
of water stress the two varieties are statistically similar,
However at control (unstress) Star II TR 77173/SLM
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significantly differed from Kauz/Weaver. This is an in-
dication that each cultivar responded differently to water
stress. The finding is similar to that of [33].
The interaction between sowing date and variety on
grain yield in 2009/10, 2010/11 dry seasons and com-
bined were significant (Table 7). The result indicated
that delay in sowing from 21st November to 2nd January
decreased grain yield both cultivars. 21st November
plants were higher in grain yield than the other late sow-
ing dates. However regardless of sowing date the two
varieties are statistically similar at. But at 21st November
and 5th December sowing dates Star II TR 77173/SLM
differed from Kauz/Weaver with higher yield in both
season and combined. Significant interaction between
sowing date and variety is an indication that cultivars
were not the same at different sowing date. The finding is
similar to that of [33].
4. Conclusion
Water stress at flowering and grain filling should be
Table 5. Interaction between water stress and sowing date
on grain yield t·ha−1 in 2009/10, 2010/11 dry seasons and
combined at Sokoto.
Grain yield (t·ha−1)
Water stress 21st
November
5th
December
19
December
2nd
January
2009/10
Tillering 3.14b 2.78bcd 1.55efg 1.21fg
Flowering 2.95bc 2.23cde 0.89g 0.85g
Grain filling 2.40b-e 2.97bc 1.70efg 1.99def
Control 5.03a 3.03bc 1.78ef 2.04def
SE± 8.154
2010/11
Tillering 4.76a-c 3.85ab 3.40c-f 3.91b-e
Flowering 3.79b-f 2.27f 2.66d-f 3.53c-f
Grain filling 4.18b-d 3.53cf 3.16b-d 2.55ef
Control 5.74a 5.18ab 4.03b-d 2.65d-f
SE± 0.537
Combined
Tillering 3.95ab 3.31b 2.47cg 2.56c-g
Flowering 3.37b-f 2.25efg 1.77g 2.19g
Grain filling 3.29cd 3.25b-f 2.43d-f 2.27efg
Control 5.39a 4.10a 2.90b-g 2.34efg
SE± 0.2987
Means followed by same letters are not significantly different using
DNMRT at 5% level of probability.
Table 6. Interaction between water stress and variety on
grain yield t·ha−1 in 2010/11 dry season and combined at
Sokoto.
Grain yield t·ha−1
Water stress
Star II TR 77173/SLM Kauz/ Weaver
2010/11
Tillering 4.63a 3.35b
Flowering 3.26b 2.87b
Grain filling3.34b 3.26b
Control 4.78a 3.70ab
SE ± 0.291
Combined
Tillering 3.47ab 2.86bc
Flowering 2.65bc 2.14c
Grain filling3.14b 2.62bc
Control 4.15a 2.89bc
SE± 0.196
Means followed by same letters are not significantly different using
DNMRT at 5% level of probability.
Table 7. Interaction between sowing date and variety on
grain yield t·ha−1 in 2009/10, 2010/11 dry seasons and com-
bined at Sokoto.
Variety
Sowing date
Star II TR 77713/SLM Kauz/Weaver
2009/10
21st November 4.02a 2.74bc
5th December 3.17b 2.33cd
19th December 1.47e 1.48e
2nd January 1.76e 1.28e
SE± 0.243
2010/11
21st November 5.08a 4.15abc
5th December 4.22ab 3.20bcd
19th December 3.78bcd 2.84d
2nd January 3.33bcd 2.99cd
SE± 0.243
Combined
21st November 4.55a 3.45bc
5th December 3.69b 2.77cd
19th December 2.63d 2.16d
2nd January 2.54d 2.14d
SE± 0.1963
Means followed by same letters are not significantly different using
DNMRT at 5% level of probability.
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Yield and Yield Components of Bread Wheat as Influenced by Water Stress,
Sowing Date and Cultivar in Sokoto, Sudan Savannah, Nigeria
129
avoided as they are the most critical growth stages in
yield determination in wheat, because plants cannot re-
cover, while delay in sowing resulted in reduction in
yield and yield components. Star II TR 77173/SLM is
therefore recommended for the area.
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