| Guar (Cyamopsis tetragonoloba L.) is an important industrial legume widely cultivated across arid and semi-arid regions. To identify salt-tolerant genotypes, the fifteen guar genotypes originating from Iran, India, and Pakistan were evaluated under three salinity levels (0, 10, and 15 dS/m) in a factorial RCBD design. Salinity imposed highly significant reductions in physiological traits and caused phenological delays in guar genotypes. Under severe salt stress (15 dS/m), seed yield decreased across all genotypes. In response to 15 dS/m NaCl, the lowest yield reductions were recorded for the genotypes S6553, Saravan, S6260, and RGC-1031, at 16.3, 20.4, 21.2, and 21.4%, respectively, demonstrating relative tolerance to salt. In contrast, the largest decrease was observed in genotypes S-5885, S6566, and S-6560, by 31.4, 30.5, and 30.5%, respectively, confirming their relative sensitivity to salt stress. Although genotypes S6553, Saravan, S6260, and RGC-1031 exhibited the lowest yield reductions at 15 dS/m NaCl, overall, genotype RGC-986 consistently displayed superior performance across all salinity levels, while genotype Pishen was the most adversely affected, exhibiting sharp declines in physiological performance and delayed phenology. Inclusive, the study demonstrated substantial genetic variability in guar responses to salinity and highlighted key physiological traits, such as chlorophyll retention, osmotic adjustment, membrane stability, and growth maintenance, as essential determinants of tolerance. RGC-986 genotype, identified as salt-tolerant, represents valuable candidates for breeding programs and for sustainable guar cultivation in salinity-affected regions. |