Comprehensive assessment of guar genotypes under saline stress: Integrating phenology, breeding and physiology

The identification and development of salt tolerant crops are significant area of interest in the pursuit of stabilizing food security in these regions. Guar, a valuable drought tolerant legume, has genotypes with different responses to salinity stress and this reflects the goal of breeding for salt tolerance. This study provided a comprehensive study with data from 15 guar genotypes across three levels of salt (0, 5 and 10 dS/m) using a randomized complete block design with three replicates. Phenotypic, morphological, and yield-related traits were assessed. Factorial ANOVA revealed highly significant differences (p < 0.001) among genotypes and salinity levels for most traits, except leaf angle and root length (for genotype effects). Tolerant genotypes (RGC-986, Grembite, RGC-1031) outperformed sensitive ones (S6486, Saravan, Pishen) in morphological, phenological, and yield traits under saline conditions. Strong positive correlations were observed between root length and seed yield (r = 0.72) and between leaf area and biomass (r = 0.81). PCA grouped genotypes into three clusters based on salinity response, with the first two components explaining 78.3% of the variance. AMMI stability analysis designated RGC-986 and Grembite as the most stable and producing genotype across all salinity levels. Mixed model analysis designated 42-68% of the total phenotypic variation to genetic variation suggesting a moderate to high genetic component with the heritability estimates on yield components indicating high heritability for these traits. In conclusion our study demonstrates the presence of substantial genetic variation in salt tolerance in the current guar genotypes, with RGC-986, Grembite and RGC-1031 as promising candidates for salt tolerant breeding programs to enhance guar production in saline soils. The study underscores the value of integrating breeding, physiological, and agronomic approaches to develop salt-tolerant guar varieties.