Comparison of grain sorghum varieties base on yield and water use efficiency under drought stress in summer cropping

Water use efficiency Increasing is an effective way to optimal water use and to achieve sustainable production in a water deficit crisis. In this regard, the effect of drought stress through four irrigation regimes (after 80 (control), 110, 140 and 170 millimeter evaporation) on four sorghum varieties (Sepideh, Kimia, Payam and KGS32) was studied in the summer of 2016 and 2017 in Khorramabad, Iran. Results showed that the morphological characteristics of plant such as plant height and grain yield components decreased with increasing drought stress. Maximum number of grain per head (2286.9 seeds) from Sepideh and maximum thousand-kernel weight (23.8 g) were obtained from Payam variety in the first year under normal irrigation conditions. The highest grain yield was obtained under normal irrigation conditions with an average of 8230.5 kg ha-1 and the lowest grain yield was obtained from irrigation after 170 mm evaporation with an average of 3917.5 kg ha-1. The highest water use efficiency for grain yield (1.55 kg m-3) was obtained from Sepideh variety in the after 110 millimeter evaporation irrigation regime. Totally, Sapieh variety at after 110 millimeter evaporation irrigation regime saves irrigation water, while producing optimal economic performance and is recommended for temperate region of Khorramabad and similar areas.