Water deficit caused reduction productivity attributes for faba bean crop. So, seven faba bean genotypes were evaluated as parents with their F1 crosses under normal and water dificit at the Experimental Farm, Faculty of Agriculture, Benha University, Egypt, during the 2021 /2022 and 2022/2023 winter growing seasons to study heterosis, combining ability and genotype behavior under different irrigation treatments. With the exception of the number of branches plant-1, very significant differential mean squares attributable to genotypes, parents, crosses, parent vs. crosses, GCA, and SCA were found for all attributes in both and across trials. Water deficit caused reductions in plant height, number of branches plant-1 , number of pods plant-1 , weight of pods plant-1 ,
number of seeds pod-1, 100-seed weight, and seed yield plant-1 by 6.05, 9.86, 15.24, 11.06, 1.03, 4.77
and10.59%, respectively. GCA/SCA ratio values which exceeding largely the unity were detected for number of branches plant-1, number of pod-1 and seed yield plant-1, in both and across irrigation treatment, revealing that additive and additive x additive gene effects account for the majority of overall genetic variability. The cross P1xP5 recorded the highest significant and positive heterosis relative to mid and better parent being 40.65% and
40.27% for seed yield plant-1, respectively . P5 (Sakha 4) and P5 (Sakha 4)xP6 (Wadi 1) exhibited the best general combiner and best specific effects for seed yield per plant, respectively. Based on stress indices TO L and SSI, the crosses P3xP6 and P4xP5 were the most tolerant genotypes based on (RSI) index. In this study P1
and P3, also the cross 3x6 had desirable values for M P ,G M P, H M , STI and Yi indices. The mention genotypes might be employed in faba bean breeding programmes under water stress.