Drought-Induced Modulation of Bioactive Compounds in Rice: A Comparative Study of Tolerant and Susceptible Varieties

In this research, the correlation between bioactive compounds and drought stress was studied in 11 rice varieties. The rice varieties were divided into treatment and control groups, and the plants were subjected to different drought conditions, including 3, 5, and 7 days without irrigation. Among the rice varieties, K8 was the most tolerant, whereas K11 was the most susceptible to water deficit. The results showed that total phenolic content increased dramatically in K8 and K11 under a 7-day treatment (71.397 and 51.381 mg gallic acid equivalent (GAE)/g, respectively). K8 showed higher antioxidant activities (DPPH = 8.832 µg/mL, ABTS = 1161.8 µg/mL, and reducing power = 1168.2 µg/mL) after 7 days of no irrigation. Contrastingly, the IC50 values indicate that K11 showed lower antioxidant activity (DPPH=16.261 µg/mL, ABTS=1944.5 µg/mL, and reducing power=3721 µg/mL) for the same variable.