Assessment of Alfalfa (Medicago sativa L.) Cultivars for Salt Tolerance Based on Yield, Growth, Physiological, and Biochemical Traits

Alfalfa (Medicago sativa L.) is one of the most valuable forage crops having an intermediate salt-tolerant level. In this fact, twelve selected alfalfa from the south Tunisia oasis were subjected to salt stress looking for their adaptability against these abiotic constraints. Hence, this work reports the sodium chloride effect (150 mM) on the basis of biomass yield reduction. For this, some cultural, physiological, and biochemical parameters were monitored. Indeed, the relative water content, the stem and leaves aspects, chlorophyll content, protein amount, free proline amount, K+ and Na+ concentrations, protease and α-amylase activities, superoxide dismutase, and catalase ones were monitored. The findings give rise to no significant salinity effect on stem length and leaf number. However, there was a significant difference in leaf color for plants under salt stress. In addition, salinity decreases both fresh and dry weight of all cultivars. NaCl treatment significantly reduced chlorophyll content and the K+ ion accumulations. Also, under salt stress, there was higher proline accumulation, Na+, and proteins in all alfalfa cultivars than under control. Additionally, these findings noticed the increase of enzymatic scavenging system related to the activity of superoxide dismutase, catalase, and protease under salt stress condition. In contrast, the α-amylase activity decreased under salt treatment. It seems from the studied parameters that our 12 alfalfa oasis cultivars are tolerant to salt stress under oasis conditions.