Exogenous Sulphydryl Improves Membrane Stabilization, Photosynthesis and Antioxidant Defense Systems in Vigna aconitifolia L. Under Water Stress

Abstract

A 2-year (2010–2011) field experiment was conducted under hot arid environment at Bikaner, India to investigate the effects of exogenous sulphydryl (–SH) compounds (thioglycolic acid and thiourea) on the water relation, malondialdehyde (MDA) content, membrane stability, photosynthetic pigment contents, gas exchange parameters and antioxidant enzyme activities in moth bean (Vigna aconitifolia L.) under water limiting environment. Foliar application of –SH compounds significantly reduced MDA content and increased membrane stability, photosynthetic pigment content, gas exchange parameters and antioxidant enzyme activities. The –SH treated plants had 9–14, 10–14, 17–25, 16–74, 14–37% higher relative water content, membrane stability index, total chlorophyll content, antioxidant enzyme activities, and net photosynthetic rate (PN), respectively, whereas the MDA content was 12–21% lower, as compared to non-treated plants. Results suggest that under water limiting situation, exogenous –SH compound application improves photosynthesis, protects plants against oxidative damage by scavenging ROS and minimizing MDA content by elevated antioxidant enzyme activities. Results indicate that exogenous –SH application enhances the activities of antioxidant enzymes and maintains higher photosynthetic rate under water limiting environment and thus helps to improve drought tolerance in moth bean.