PHYSIOLOGICAL EVALUATION OF SOME FABA BEAN CULTIVARS UNDER WATER DEFICIT CONDITIONS

A field experiment was conducted at El-Gemmeiza Agriculture Research Station, Elgharbia Governorate, Egypt, during the two successive Winter seasons 2017/2018 and 2018/2019 to evaluate four faba bean cultivars (Nubariya 2, Giza 716, Sakha 3 and Misr 1) under water deficit conditions. Water deficit was created by irrigating faba bean plants once only (I1), compared to I2, I3 and I4 irrigation treatments which received additional irrigation at 50, 65 and 80% of available soil moisture depleted, respectively. Water deficit (I1) significantly decreased plant height, branch number plant-1, leaf area index, dry matter plant-1, crop growth rate, pod number plant-1, seed number plant-1, seed weight plant-1, 100-seed weight, seed and straw yields fad-1 as well as total chlorophyll of leaves, whereas such treatment (I1) significantly increased osmatic potential, water use efficiency, seed nitrogen and protein (%). In contrast, applying irrigation treatments (I3) significantly increased all mentioned traits except osmatic potential, nitrogen and protein (%) of seeds which were decreased. Irrigation regime (I3) increased pod number plant-1 seed number plant-1, seed yield plant-1, seed and straw yields fad-1 by 21.03, 14.36, 21.00, 26.46 and 27.54 (%), respectively but 100- seed weight increased by10.35% at (I4) compared with irrigation regime (I1). Each faba bean cultivar i.e. Nubaryia 2 and Giza 716 recorded the highest value for each of dry matter plant-1, leaf area index, crop growth rate, branches number plant-1, seed yield plant-1, water consumptive use, water use efficient, total chlorophyll of leaves compared to the other two cultivars (Sakha 3 and Misr 1) but osmatic potential was decreased. In addition, Nubaryia 2 cultivar significantly surpassed the other cultivars (Giza 716, Sakha 3 and Misr 1) in plant height, 100- seed weight, nitrogen and protein (%) of seeds, while Giza 716 gave the highest value for each of pod number plant-1 and seed yield fad.-1 than that of other cultivars but Misr 1 produced the lowest value of the previous traits. The interaction effect between irrigation regimes and faba bean cultivars was significant for all mentioned traits except branches number plant-1 and straw yield fad.-1.The maximum values for each of LAI, DM, CGR, pod number plant-1, seeds number plant-1, seed yield fad.-1, RWC and total chlorophyll of leaves were obtained when Giza 716 cultivar received irrigation regime (I3), but Misr 1 recorded the lowest values for the same traits under irrigation regime (I1). This work recommends sowing faba bean plants Nubaryia 2 cultivar with applying life irrigation only; such treatment (I1) save about 29.38-34.76% of consumptive use (WCU) with accept reduction in seed yield about 11.11- 13.02 % if irrigation water was not enough and sowing Giza 716, Sakha 3 and Misr 1 in the presence of water abundance (I3).