BICHEMICAL STUDY OF SOME FABA BEAN (Vicia faba L.) CULTIVARS UNDER DIFFERENT WATER REGIMES IN SANDY SOIL

Drought stress is one of the major environmental obstacles that limit production and development of faba bean. In this study, two field experiments were conducted at the experimental station of the National Research Center, Nubaria district, El-Behara Governorate, Egypt, during 2019/2020 and 2020/2021 winter seasons to evaluate the responses of three faba bean cultivars (Nubaria 1, Nubaria 2 and Giza 843) to different water regimes (100%, 75% and 50% water irrigation requirement). The results showed decreases in shoot growth (plant height, shoot dry weight and leaves area), photosynthetic pigments, endogenous indole acetic acid (IAA) total carbohydrates contents (TCHO) of faba bean leaves with decreasing water irrigation from 100% to 75% and 50% WIR and the degree of decreases differed among the tested cultivars. On the contrary, root length and root dry weight were increased under decreased WIR (75% and 50%). Moreover, yield and its components were decreased under water deficit conditions (75% and 50% WIR) accompanied with decreases in total carbohydrates, protein contents while increased phenolic and vicine contents of the yielded seeds. With regard to cultivars, data show a significant varietal variability for most studied parameters. The superior cultivar identified was Nubaria-1, as it gave the highest growth and yield components under the three levels of WIR. In conclusion, it is worthy to mention that, the performance of Nubaria -1 variety was more pronounced than that of Nubaria-2 and Giza-843 cultivars grown under the three levels of water irrigation (100%, 75% and 50% WIR). From the obtained results, it can be concluded that sowing Nubaria -1 cultivar under (75%) water irrigation requirement WIR produced the highest value of water used efficiency (WUE), although 75% WIR significantly reduced seed yield compared with 100% WIR irrigation treatment. Our recommendation is to cultivate cultivar under (75%) WIR, since it produce quit reasonably yield and save nearly 200 m(3) irrigation water especially under the circumstances of climate of Nubaria district, El-Behara Governorate, region.