Amelioration of Salinity Stress in Chickpea (Cicer arietinum L.) Cultivars Through Foliar Spray of Proline and Glycine Betaine

Chickpea is an economically important legume that is susceptible to various abiotic stresses, including salinity. The intrinsic stress tolerance mechanisms in chickpea are effective under mild conditions but are compromised under severe stress. The present study evaluated the impact of 50 and 100 mM NaCl-induced salinity stress for two chickpea cultivars (PDG4 and GPF2) along with the ameliorative potential of 50 mM proline and Glycine betaine (GB) foliar spray. A comprehensive assessment was conducted encompassing growth and biomass traits, relative leaf water content, photosynthetic pigments, membrane stability, reactive oxygen species (H₂O₂, ^•O₂⁻), total protein, phenolic and flavonoid content, as well as antioxidant enzyme activities (SOD, CAT, APX). Salinity stress of 50 and 100 mM decreased the total biomass accumulation by 23.3% and 26.2% in PDG4, and 27% and 33.7% in GPF2, respectively. Foliar application of proline significantly improved the biomass by 7.6% in PDG4 and 8.7% in GPF2 under 50 mM as compared to control. Similarly, proline and GB application enhanced SOD activity by 42.7% and 27.7% in PDG4, and by 51% and 41.1% in GPF2 under 50 mM of salinity stress. CAT followed a similar trend as SOD, while APX exhibited an opposite pattern. Notably, PDG4 displayed higher resilience under both stress levels, and proline was more effective than GB in mitigating stress effects, as further supported by correlation matrices, heatmap clustering, and PCA. These findings underscore the potentiality of compatible solutes, particularly proline, in enhancing salinity tolerance in chickpea and offer promising strategies for sustainable crop management in salt-affected soils.