ORIGINAL ARTICLE

Evaluation of morphological, physiological, biochemical responses under drought stress at vegetative stage of rice (Oryza sativa) cultivars

To evaluate drought stress's morphological, physiological, biochemical responses on the vegetative stage of rice cultivars, a pot experiment was carried out using a complete randomized design (CRD) with three replications during the rice growing season of three experimental years (2021 to 2023). Five rice cultivars, namely Chakhao poireiton, Chakhao angangba, Chakhao angouba, and Heitup phou, collected from Wangbal rice research Centre, Thoubal, Manipur, and drought drought-tolerant check variety, namely Sahbhagi Dhan, for comparison of tolerance to drought stress was used as a positive control, collected from International Rice Research Institute (IRRI), Odisha. The five rice cultivars were subjected to four different levels (0, 10, 15, and 20 days) of drought stress treatments. Our studies revealed that under drought stress treatment, out of the five rice cultivars, R002 and R003 cultivars were found to be significantly reduced in plant height, tiller number per hill, chlorophyll accumulation, and RWC %, whereas R001 and R004 were least affected as compared to the tolerant check cultivars(R005). Drought stress induced significant accumulation of osmolytes and antioxidant activity, while out of the five rice cultivars, maximum accumulation was observed in R001 and R004 compared to R005 cultivars.  The overall conclusion from this study, in comparison to the drought-tolerant cultivar, R004 and R001cultivars possessed maximum degree of drought tolerance and showed more triggered activity antioxidant enzyme, proline content, total soluble sugar, total phenolic content, total soluble protein content, and free amino acid content, while cultivars R002 and R003 found to be more sensitive to drought stress.