Exploring Salt Stress Tolerance in Horsegram (Macrotyloma Uniflorum): Insights from Growth, Physiological and Biochemical Approaches

Soil salinity is one of the significant challenges affecting seed germination, growth, physiology, and crop productivity worldwide. Horsegram is known for its higher tolerance to stress conditions than other legumes and therefore is a potential pulse and fodder crop in salt-affected areas. During this study, 25 horsegram genotypes were screened under a controlled environment to identify salt-tolerant and sensitive genotypes based on the salt tolerance index and membership function value of 10-day-old seedlings. DH-22 and DH-29 were identified as salt-tolerant, while DH-11 and DH-12 were identified as salt-sensitive genotypes. These genotypes were further analyzed under 0, 50, 100, and 150 mM NaCl treatments to examine various growth, physiological, and biochemical parameters. The analysis revealed that the tolerant genotypes exhibited higher root and shoot length, dry and fresh weight, relative water content, chlorophyll and carotenoids content, free proline and phenolic content, and enhanced activity of antioxidant enzymes such as catalase, ascorbate peroxidase, glutathione reductase, superoxide dismutase, and guaiacol peroxidase. Further, lipid peroxidation, hydrogen peroxide content, and percent ion leakage decreased in the tolerant genotypes than in the sensitive genotypes. Additionally, the tolerant genotypes displayed less cell death and lower accumulation of H2O2 and superoxide ions in histochemical staining, which may play a vital role in cellular protection during salt stress tolerance.