Effect of salt stress on leaf photosynthetic and antioxidant traits of Vicia faba genotypes

Salinity is a serious and increasing problem for the agriculture sector in the world due to the expected climate change and water scarcity. This study aimed to screen the tolerance of eleven Egyptian genotypes/ cultivars (Giza716, Giza843, Masr 1, Nubaria 1, 3, 4, and 5, Sakha 1, 3, and 4, and Wadi 1) to salinity stress. The plants were grown under three salinity treatments in addition, to control (T1= 50 mM, T2= 75 mM, and T3= 100 mM NaCl). Biomass, biochemical, and leaf photosynthetic parameters were measured. The results revealed that increasing salinity stress led to a significant increase in soluble proteins, sugars, and phenolic compounds in the leaves of all genotypes compared to the control. Maximum transpiration rate and stomatal conductance values were under control conditions, while the minimum values were under T3 salinity treatment. The photosynthetic rates were generally decreased by increasing salinity stress except for Nubaria 3. The photosynthetic rates of Masr 1, Nubaria 1, and Nubaria 5 genotypes decreased by > 50% of their photosynthetic rate (A) values at T3 compared to their control. The Intrinsic water-use efficiency (iWUE) was remarkably high at T3 salinity treatment for all genotypes. The maximum increment of the antioxidant enzyme CAT activity under salinity stress was recorded in Nubaria 3. We can conclude that the Nubaria 3 genotype was considered the most tolerant genotype to salinity in terms of having better photosynthesis performance and antioxidant activity under salinity stress.