Effect of Jasmonic Acid Foliar Spray on the Morpho-Physiological Mechanism of Salt Stress Tolerance in Two Soybean Varieties (Glycine max L.)

Abstract

Jasmonates (JAs) are lipid-derived compounds that function in plants as key signaling compounds during stressful conditions. This study aimed to examine the effects of exogenous fo-liar-JA application (100 μmol L−1) on the morpho-physiological response of two soybean varieties (parachinar-local and swat-84) grown under different NaCl regimes (0, 40, 80, and 120 mM). Results show that exogenous JA application alone and in combination with salt stress altered the growth and metabolism of both soybeans. For instance, they accumulated significant amounts of Na+ and Cl–, while their K+, Mg2+, Fe2+, Mn2+, B3+, and P3+ contents were low. Further, photosynthetic pigments Chl a and Chl b increased at low concentrations of salt and exogenous JA. Car decreased under both salt and exogenous JA as compared with untreated control. In addition, sugar, phenol, and protein content increased under both salt and exogenous JA application. In contrast, the exogenous JA application alleviated the negative impact of salt stress on the growth and metabolism of both soybeans. Further, the high concentrations of soluble protein and phenol in the leaves of both soybeans may contribute to their ability to adapt to salinity. However, molecular studies are necessary to understand the ameliorative role of exogenous JA in the growth and metabolism of salt-treated young seedlings in both soybean varieties.