162 V. G. Kakani et al.
60 m length. The main irrigation treatments had a bulk bed in between to restrict
water seepage between treatments.
The experiment was planned at two sowing dates to ensure that the crop was
exposed to high temperature during the sensitive period of flowering. Sowing 1 was
on 21st January and sowing 2 was on 26th February. The experimental design was
split–split plot with two irrigation regimes as main plots—irrigated (IR) and fully
irrigated—replacing 100 % of crop evapotranspiration (ETC) and water-stress (WS)
irrigation with only 40 % of ETC from flowering to harvest otherwise fully irrigated;
temperature treatments as subplots—ambient temperature (T1), high-temperature
sowing 1 (T2), ambient temperature sowing 2 (T3) and high-temperature sowing 2
(T4); and genotypes TMV2 and ICGS11 as sub–subplot.
8.2.3 Cultivars and Sowing
TMV 2: This cultivar was released in 1940. TMV 2 is a Spanish botanical type, a
selection from ‘Gudhiatham Bunch’ and a local variety. It is widely adapted, well
suited for rainy and summer season cultivation in southern India. This cultivar is
moderately tolerant to water stress and high temperature.
ICGS 11/ICGV 87213: This cultivar was released in 1986. This cultivar is a Span-
ish botanical type, selection from natural hybrid population of Robut 33-1. It has
above-average tolerance to end-of-season drought. It is also photoperiod insensitive,
adapted to post-rainy season cultivation in India and performs well in West Africa.
Prior to sowing, seeds were treated with fungicide mixture, Thiram + Captan
(3:1). Seeds of cultivars TMV 2 and ICGS 11 were sown manually, 5 cm deep
and 10 cm apart in furrows made at 30 cm spacing on broad beds. An iron chain
with tags at 10 cm spacing was used to ensure that each plot received the required
number of plants. Soon after emergence, gaps were filled for ungerminated seeds.
Appropriate weed, pest and disease control measures were taken to maintain a
healthy crop stand.
8.2.4 Stress Treatments
8.2.4.1 Irrigation
Immediately after sowing, all plots were irrigated using an overhead sprinkler sys-
tem. A second sprinkler irrigation was given after 7 days to help seedlings emerge.
A drip irrigation system was then installed to provide adequate irrigation to the
growing seedlings. The drip irrigation system is shown in Fig. 8.2b and c. The drip
emitters were calibrated so that each supplied 10 L h−1 of water to crop plants. This
ensured that all plants in the plot were supplied with equal amount of water. Plots
were irrigated at 3-day intervals. Fully irrigated plots were replaced with water
equal to that lost through evaporation. Water stress (WS) plots were irrigated with