8 Effect of High Temperature and Water Stress on Groundnuts ... 161
received above the crop canopy was measured in each treatment using line quantum
sensors (LI-191SB, LI-COR Ltd). Measurements were logged at 10-s intervals and
averaged every 15 min throughout the crop-growth period. Daily weather was also
collected from a meteorological observatory located within 500 m of the experi-
mental site.
The soil at the experimental site was a reddish-brown alfisol, a member of isohy-
perthermic family of Udic Rhodustalf. Soil pH was 6.5. Depth of soil in the site was
120 cm. The soil moisture was 20 % w/w at field capacity and 8 % w/w at permanent
wilting point. These soils are well drained with moderate permeability.
8.2.2 Field Preparation and Experimental Design
The field site was ploughed to a depth of 30 cm with mouldboard and disc ploughs 15
days before sowing. The ploughed field was then laid into broad beds (1.2-m wide)
and furrows (0.3-m wide), in an East–West direction (Fig. 8.2a). The beds were then
levelled and compacted. Four furrows at 30-cm spacing and 5-cm depth were then
opened on the bed surface along the length of the bed. The whole area was then
divided into two halves, one for each sowing. Each sowing composed ten beds of
Fig. 8.2 Pictures showing a broad bed and furrow system with mini—weather station; b Line
quantum sensor and thermocouples (TC) for measuring air (inside the cup) and soil temperature
(10 cm below soil surface), c Layout of heat tunnels in the field, and d Inside of the high tempera-
ture × irrigation treatment heat tunnel