Evaluation of Rice (Oryza sativa L.) Genotypes under Controlled Submergence Conditions

The cultivation of rice (Oryza sativa L.) in flood-affected areas of Bangladesh is severely hampered by submergence stress, particularly during the Aman season. This study aimed to identify suitable rice varieties for flood-prone locations and evaluate the submergence resistance of particular genotypes. Eleven advanced breeding lines along with three tolerant check varieties (Binadhan-11, Binadhan-12, and BRRI dhan52) and one susceptible check variety (BRRI dhan28) were used in the study, which was conducted at the Bangladesh Institute of Nuclear Agriculture (BINA) in Mymensingh. In addition to a non-submerged control, two submergence treatments (15 and 20 days) were imposed during the vegetative phase in a factorial experiment following a completely randomized design (CRD) with three replications. ANOVA, correlation, and genetic parameter analyses were used to evaluate morphological and yield-associated traits. Significant variations (p < 0.001) were observed among genotypes for all studied characteristics. Numerous lines, such as IRSSTN-FP-2, IRSSTN-FP-5, IRSSTN-FP-7, IRSSTN-FP-8, IRSSTN-FP-10, and IRSSTN-FP-12, demonstrated high tolerance with consistent performance under pressure. Submergence greatly decreased plant height, number of tillers, length of panicles, filled grains, and weight of seeds, with more substantial decreases during extended stress. Yield components showed significant positive associations, particularly filled grains, effective tillers, and total tillers. The high estimates of broad-sense heritability and genetic advance for key traits indicated the substantial contribution of genetic variation and the potential effectiveness of selection for improving these traits. These findings highlight seed weight, filled grains, and effective tillers as reliable selection factors for producing high-yielding rice cultivars resistant to submergence.