Growth and Adaptation of Soybean Cultivars under Water Stress Conditions : I. Leaf movement and leaf temperature

Abstract

The leaf movement of soybean under water stress conditions was investigated in terms of canopy structure and leaf temperature. Irrigated and non-irrigated treatment were conducted in concrete plots in the field in Xingjiang, China. Two determinate cultivars with different leaf movement, Heinong 33 (inactive) and Zhengzhuta 2 (active), were used. The leaves of the non-irrigated plot in Zhengzhuta 2 actively moved parallel to the sun rays. The irrigated plots of Zhengzhuta 2 and Heinong 33 also had the paraheliotropic leaf movement, which were not so active as compared with the non-irrigated plot of Zhengzhuta 2. The leaves of the non-irrigated plot in Heinong 33 showed signs of wilting during the day. In Zhengzhuta 2, the leaf temperature of the terminal leaflet of the upper layer in the non-irrigated plot was lower than the air temperature during most of the day. The leaf temperatures of the irrigated plots in both cultivars were a little higher in the morning and lower in the afternoon than air temperature. The non-irrigated plot in Heinong 33 had rather high leaf temperatures as compared with air temperature. Five days after irrigation, the non-irrigated plot of Zhengzhuta 2 had a similar pattern of leaf movement as before the irrigation.