Growth response and antioxidant enzyme activity of Cassia occidentalis exposed to soil moisture stress

Biotic and abiotic stresses exert a considerable influence on the growth and physiology of plants. Water stress is one of the most important abiotic stress factors. The study was carried out to elucidate the effect of drought stress on growth, physiology and antioxidant enzyme activity of Cassia occidentalis experiencing four water regimes with soil relative water content ranging from 65% to 12%. Plants were grown in pots and treated with three irrigation levels (100ml, 200ml and 300ml).The experiment was laid out in complete randomized design (CRD) with three replicates. Data on growth, physiological parameters and antioxidant enzyme activity were recorded and analyzed statistically. Physiological parameters like leaf area index, biomass accumulation, relative water content and membrane stability index decreased significantly with decrease in water level, but mild level of water treatment enhanced the growth. The plant exhibited an increase in antioxidant enzyme activity under stressed condition which proves its tolerance against drought. Thus it can be concluded that Cassia occidentalis plant is able to tolerate a limited water levels by enhancing its antioxidant defense but excessive drought markedly affected the enzyme activity and so depleted the plant growth.