ENHANCING YIELD OF CLUSTERBEAN ( CYAMOPSIS TETRAGONOLOBA L. TAUB) WITH FOLIAR APPLICATION OF SULPHYDRYL COMPOUNDS UNDER HOT ARID CONDITIONS

Water stress is one of the main environmental stress conditions that adversely affect growth and yield of crops. Sulphydryl (-SH) compounds have been reported to induce tolerance to abiotic stress conditions. A two-year (2010 and 2011) experiment was conducted at Bikaner, Rajasthan, India to test whether the exogenous applications of thiourea (500, 750 and 1000 mg L −1 ) and thioglycolic acid (200, 300 and 400 mg L −1 ) as a foliar spray would alleviate deleterious effects of water stress on clusterbean ( Cyamopsis tetragonoloba L.). The -SH-treated plants showed higher membrane stability index, photosynthetic pigment content, photosynthetic capacity and antioxidant enzyme activities and lower lipid peroxidation compared with untreated plants. Compared with untreated plants, the -SH-treated plants had 11–18, 18–30, 17–57, 25–47, 14–22% higher membrane stability index, total chlorophyll content, antioxidant enzyme activities, net photosynthetic rate and seed yield, respectively; whereas the malondialdehyde content was 10–19% lower. These data suggest that under water deficit stress, exogenous -SH compound application improves photosynthesis by increasing photosynthetic pigment, protects plants against oxidative damage by scavenging reactive oxygen species and minimizing lipid peroxidation by elevated antioxidant enzyme activities. These results indicated the role of -SH compounds in diminishing the negative effects of water deficit on clusterbean and suggest that -SH compounds could be used as a potential bioregulator to improve plant growth and yield under water deficit conditions.