Phytochemical response in rice (Oryza sativa L.) genotype during the vegetative and reproductive stage under drought stress and non-stress conditions

Drought stress is a serious threat which decreases crop production. The present investigation was taken up to study the effect of drought stress at vegetative and reproductive stages on potential biochemical and enzymatic responses were investigated in two rice cultivars Rashi (tolerant) and Swarna (sensitive). Here, we observed significant changes in the biochemical and enzymatic responses between control and treatments as well as between the genotypes. Activity of catalase, peroxidase and superoxide dismutase (SOD), and glutathione reductase were also found to be different among the rice cultivars. Moreover, phenol content and activity of superoxide dismutase, catalase and glutathione reductase were increased significantly under drought stress in Rashi compared to Swarna. Nitrogen assimilatory enzymes such as nitrate and nitrite reductase (NiR) were sensitive to drought stress and both the genotype showed decreased activity at reproductive stage. Catalase activity was significantly higher at controlled reproductive (11.72%) and vegetative stage (4.14%) compared to Swarna. Rashi also showed an elevated SOD activity in controlled reproductive (180.55%) and vegetative stage (7.67%) compared to Swarna. Similarly, highest NiR activity found in Swarna (17.03%) compared to Rashi. Highest nitrate reductase activity was found in Rashi (10.87%) compared to Swarna. Rashi showed significantly higher chlorophyll content in vegetative stage and decreased in reproductive stage (26.33%). The improved performance of drought tolerant genotype (Rashi) was associated with more efficient biochemical factors under conditions of stress compare to drought sensitive genotype (Swarna).