Salicylic Acid Improves Nitrogen Fixation, Growth, Yield and Antioxidant Defence Mechanisms in Chickpea Genotypes Under Salt Stress

Salinization of farming soils is a major abiotic stress hampering crop growth and productivity globally. Chickpea is a vital legume crop, being cultivated largely in rainfed drylands and is sensitive to salt stress. Salicylic acid (SA) is an important signalling molecule, which improves plant stress tolerance; nevertheless, the underlying mechanisms behind SA-mediated defence responses under salt stress, especially in chickpea, are unclear. Thus, pot experiments were carried out to investigate the role of SA (0.5 mM) seed priming on growth, nitrogen fixation, photosynthesis, ROS production, antioxidant defence system and yield in two chickpea (Cicer arietinum L.) genotypes (GPF-2 and PBG-7) subjected to salt stress (80 mM). Results revealed that salinity stress reduced the nodulation, nitrogen fixation (leghemoglobin content), photosynthetic pigments and growth, which eventually affected yield output, more in PBG-7 than in GPF-2. Despite the enhanced antioxidant mechanisms [superoxide dismutase, catalase, peroxidase, phenols, proline, lignin] under salt stress, ROS (O2•− and H2O2) accumulation increased significantly and induced lipid peroxidation and electrolyte leakage. However, pre-soaking (priming) of SA retained biomass, photosynthetic efficiency, arrested nodule senescence and decreased oxidative stress via enhanced stimulation of ROS scavenging machinery, consequently increasing the productivity in a genotype-dependent manner. Our study emphasized the use of SA-seed priming as an eco-friendly approach for improving salt tolerance and accomplishing sustainable production of chickpea genotypes in salt-affected soils.