Optimization of Water Consumption of Soybean under Drought Conditions

Water scarcity for agricultural productions increases steadily and development of new water resources incurs heavy cost. Study on the reaction of different crops to deficit irrigation is an important step for improving management and optimal use of water. To evaluate the response of two soybean cultivars to different irrigation regimes, the current research was conducted in the crop year 2006 in Gorgan research station. The experiment was arranged in a randomized complete block design as split-plot with three replications. Irrigation treatments of 100 (I100), 75 (I75) and 50 (I50) percent of the irrigation requirement comprised main plots and the subplots were two soybean cultivars: DPX (semi determinate and late maturity) and SEPIDEH (indeterminate and early maturity). Results showed that drought stress (I50) had negative significant effec on: node number, plant height, pod number and yield. Furthermore, there was no significant difference between I100 and I75. DPX cultivar by producing higher number of branches, pods and seed weight led to an increase in yield compared to the SEPIDEH. Moreover DPX cultivar with greater water use efficiency (0.88 kgm-3) than to SEPIDEH cultivar (0.66 kgm-3) would consume less irrigation water for the same yield and might be more tolerant to water deficit.