Comparative study of early growth stages of 25 guar (Cyamopsis tetragonoloba L.) genotypes under elevated salinity

Thar region in Pakistan has an extremely arid climate and agriculture in the region is facing the dual challenges of freshwater scarcity and elevated salinity. Long-term viability of agriculture in this region depends on selection of appropriate crops/cultivars that can withstand the higher salinity. Guar can be a viable fodder, vegetable and industrial crop in water scarce areas but its salinity tolerance varies widely among genotypes. This pot culture study conducted outdoor, evaluated early vegetative growth of 25 guar genotypes under four salinity levels (0.6, 3, 6 and 9 dS m(-1)). Length, fresh weight, and dry weights of shoot and root samples and monovalent cation concentrations in leaf samples were determined to evaluate genotypes performance after 15, 30 and 45 days of sowing. Results indicated a wide genotypic variation in length, fresh and dry weights of shoot and roots at different salinity levels. Selective ion uptake was the dominant salinity tolerance mechanism, with tolerant cultivars having higher K and higher K/Na ratios at higher salinity levels. Out of 25 guar genotypes, eight genotypes performed well under the highest level of irrigation water salinity (9.0 dS m(-1)) evaluated in this study and were considered to be salt tolerant. All the genotypes registered 50% or more growth at 6 and 3 dS m(-1) compared to that at control. Our study results indicated a potential for select cultivars of guar in the salt affected regions of the world. Growth variability in guar genotypes at different salinity levels warrant further examination of these results under field conditions.