Water stress is the most limiting abiotic stress factor for soybean growth, development and production in semi-arid regions. The development of new soybean cultivars with high efficiency and ability to drought resistance is very important. Field experiment was conducted to investigated the impact of irrigation regimes at different growth stages [Full irrigation, irrigation regimes at vegetable growth, flowering, and pod full stages] on yield and yield components of two soybean varieties [1448 and Egyptian] under semi-arid regions. The results indicated that irrigation regimes had significant effect on most of traits except the weight of plant. The pod full stage higher affected by the drought than other stages on most of parameters tested. Irrigation regimes at pod full stage reduced the number of pods plant-1 by 38.4% and 26.0%, weight of pods plant-1 by 23.7% and 53.6%, number of seeds plant-1 by 29.0% and 28.8%, seeds weight plant-1 by 17.2% and 38.8%, 100-seeds weight by 35.3% and 38.1% for 1488 and Egyptian respectively. While, irrigation regimes at flowering stage decreased the weight of plant for Egyptian by 57.5% and seed yield by 24.4% and 31.2% for 1448 and Egyptian respectively as compared with same variety at full irrigation. Varieties had significant differences on plant weight, number of pods plant-1, number of seeds plant-1, harvest index, and seeds yield. In conclusion, the soybean cultivars used in this study were very sensitive to water stress. The 448 cultivar is recommended due to having higher seed yield and yield components in the study conditions.
Keywords: Grain yield; harvest index; legume crops; irrigation regimes; yield components.