Physio-Biochemical Responses of Different Zinc-Rich Rice Varieties Subjected to Drought Stress

Scarcity of water is one of the main critical constraints to rice production. This study evaluated the drought tolerance of four zinc-enriched rice varieties- BRRI dhan74, BRRI dhan84, BRRI dhan100, and Binadhan-20, along with BRRI dhan66 as a drought-tolerant positive control. Rice seedlings were subjected to controlled drought conditions in earthen pots. After 30 days under drought stress, various physiological and biochemical parameters such as chlorophyll and carotenoid contents, osmolyte accumulation (proline, total soluble sugars), antioxidant enzyme activities (CAT, POD, APX), relative water content, and morphological traits of the rice seedlings were analyzed. Results demonstrated significant varietal differences in drought response. BRRI dhan84 demonstrated superior performance with minimal chlorophyll loss (12.25% reduction compared to respective control group), enhanced antioxidant activity (200% increase in CAT and 97.53% increase in APX), and moderate reductions in shoot and root growth (45.46% reduction in root length and 17.13% reduction in shoot length), closely resembling the effects observed in BRRI dhan66. Principal component analysis supported BRRI dhan84’s favorable clustering under stress. The findings suggest BRRI dhan84 is a promising candidate for cultivation in drought-prone regions, offering a dual advantage of micronutrient biofortification and abiotic stress resilience.