164 V. G. Kakani et al.
subsample of five plants was tagged at flowering in each of the harvest areas. Daily
flower production was recorded on these plants from flower appearance for a period
of 30 days. These plants were also used to determine leaf area and partitioning of
dry matter to leaves, stems, and pods. Observations were also made on plant height,
node and leaf number, peg and pod number on plants of the subsample. To deter-
mine dry weights, plant components of the subsample and the remaining part of the
large sample was oven dried at 80 °C for 3–4 days and weighed. Total dry matter
and pod yields were recorded at harvest maturity in all replications of the experi-
ment using an area of 4 × 1.2 m.
8.2.7 Statistical Analysis
All the data were analyzed using an analysis of variance procedure (ANOVA) for
split–split plot design in Genstat 5 (Genstat 5 Committee, 1997 ). All percentage val-
ues were angular transformed before analysis to ensure homogeneity of variances.
Pod dry weight values were multiplied by a factor of 1.65 to account for energy
spent to synthesize oil in the seed (Duncan et al. 1978 ). Statistical significance was
tested by applying F-test at < 0.05, < 0.01 and < 0.001 level of probability, represent-
ed by , and , respectively.
8.3 Results
8.3.1 Weather (Temperature and Relative Humidity)
A range of temperatures was imposed during flowering by using two sowing dates
combined with heat tunnels. As photoperiod did not vary much at the experimental
site (mean 12 h ± 45 min), and the genotypes used were insensitive to photoperiod,
results are described in terms of differences in mean temperature between treat-
ments, rather than by sowing dates. Daily maximum and minimum temperatures
recorded during the crop period in all the four treatments are presented in Fig. 8.3.
Temperatures to which different development phases were exposed to in each of the
temperature treatments are given in Table 8.1.
A combination of sowing dates and heat tunnels gave mean temperatures from
sowing to maturity of 26.3° (T1), 27.3° (T2), 29.0°(T3) and 29.7 °C (T4). The heat
tunnels were capable of raising day temperature by > 10 °C compared to ambient
(Fig. 8.3). During the 20-day high-temperature treatment at flowering, mean tem-
peratures were 33.8° (T1), 41.6° (T2), 38.7° (T3) and 43.5 °C (T4). Increase in soil
temperature was also observed with increase in air temperature (Table 8.1). Temper-
ature of the soil was highest in the T4 treatment where air temperature was highest.
Average daily relative humidity (RH) in the ambient treatments T1 (sowing 1) and
T3 (sowing 2) was 48.4 % (SE ± 0.95) and 44.3 (SE ± 0.98), respectively (Fig. 8.3).