Analysis of agro-morphological, physio-biochemical, and genetic diversity in some selected landraces of rice during early drought stress

Drought severely threatens global rice production, particularly in West Bengal's red-lateritic zone, where early-stage physiological drought from erratic rainfall persists. In this study, twenty-two landraces from West Bengal and seven check varieties were subjected to drought stress at seedling stage for fifteen days under field condition. The landraces were chosen according to their better ability and response to in vitro screening. The seedlings were planted in 30 cm plastic pots and placed under a temporary plastic shade to allow controlled water supply. Root and shoot length (RL, SL), seedling-vigor-index (SVI), root fresh and dry weight (RFW, RDW), leaf rolling (LR), leaf drying (LD), proline (PRO), total carbohydrate (TCC), chlorophyll (CHL) and relative water content (RWC) were recorded. After 15 days of stress, re-watering was done and subsequently survivability percentage (SP), days to 50% flowering (DF) and maturity (DM), 100-seed-weight (SW), seed yield/plant (SY/P) were noted. Significant positive correlation was found between SP, SW, DM, DF, RFW, SL, PRO, TCC, CHL, RWC, and SY/P whereas LD, LR were found to be negatively correlated with SY/P. T-test revealed that sixteen germplasms did not vary significantly in SY/P. Landrace Morogjhota outperformed the check varieties in yield. Genetic diversity analysis with twenty drought-associated SSR markers divided the germplasms into two main clusters with a PIC value of 0.544 – 0.907. From this study, sixteen lines were identified among which five landraces showed high Drought Resistance Index which can be used as parent material in developing climate-resilient varieties and can also be used to detect major QTLs associated with drought tolerance.