Impact of methyl jasmonate on antioxidant enzymes activity and nutrients content of cowpea under salt stress

In order to investigate the role of methyl jasmonate on salinity tolerance of cowpea, a factorial pot experiment was conducted in the basis of completely randomized design with three replications in the Rey region in 2015. Treatments included three levels of seed soaking in methyl jasmonate solution (0, 25 and 50 µM) for 20 hours and three levels of salinity (0, 50 and 100 mM NaCl). The results showed that by increasing salinity levels, lipids peroxidation, antioxidant enzymes activity (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) and Cl- concentration in the leaves increased, while the concentration of N, Ca2 and Mg2 decreased as well as Kﳖ ratio. These changes eventually led seed yield to decrease. Seed treatment with methyl jasmonate had not significant effect on any measured traits under normal conditions, however this treatment (especially 50 µM) under salt stress conditions caused further activity of antioxidant enzymes, declining lipids peroxidation, reducing the concentration of Cl- in the leaves, increasing the concentration of N, Ca2 and Mg2 as well as Kﳖ ratio, and finally improved seed yield. These findings suggest that methyl jasmonate plays a pivotal role in inducing salinity tolerance of cowpea plants via enhancing antioxidant enzymes activity and altering nutrients composition.