Evaluation of Guar (Cyamopsis tetragonoloba L.) genotypes performance under different irrigation water salinity levels: Growth parameters and seed yield

Water scarcity and salinity are the major challenges faced by arid regions such as Thar Desert in Pakistan. Developing information on salt tolerance of genotypes and appropriate salinity management practices are necessary to ensure long-term viability of agriculture in these stressed environments. This study evaluated growth and seed yield of 25 different guar genotypes irrigated with waters having varying salinity (control - 0.6, 3, 6 and 9 dS m(-1)) under field conditions to characterize their salt tolerance. Results indicated salinity levels had significant influence on growth and yield of guar crop. At the highest salinity level of 9 dS m(-1), out of 26 genotypes three genotypes (S-6005, S-8885 and 2/1) showed less than 20% reduction in plant height, one genotype (BR 90) had 15% reduction in number of branches and two genotypes (S-6049 and S-5611) produced 70% of the branches compared to control. Seed yields of genotypes ranged from 0.94 to 1.82 Mg ha(-1) under control salinity but at 9 dS m(-1) it ranged from 0.28 to 0.89 Mg ha(-1). BR 99 produced highest seed yield under both control and highest salinity levels. Straw yield ranged from 0.89 to 3.34 Mg ha(-1) under control and the range was reduced to 0.57 to 1.4 Mg ha(-1) at 9 dS m(-1). Sodium concentration increased whereas K concentration and K/Na ratio decreased with increasing salinity levels in both straw and seed samples of all the guar genotypes evaluated in this study. Based on salinity tolerance index (STI) and geometric mean productivity (GMP), out of 25 guar genotypes only four (BR-99, S-5608, 2/1, S-5615 and S-8885) were considered as tolerant. Results of our study indicated that select genotypes of guar can be appropriate for water scarce and salt affected arid regions of the world.