Effect of Drought on Physiological Traits at Reproductive Stage in Six Rice Genotypes (Oryza sativa L.)

Background and Objective: Photosynthesis, the most fundamental and intricate physiological process in all green plants, whose rate depends upon the amount of chlorophyll, is also severely affected in its reproductive phases by drought stress. Therefore, a pot experiment was performed to study drought tolerance mechanism(s) based on physiological traits in six rice genotypes. Materials and Methods: Twelve treatments (6 genotypes×2 irrigations) were arranged in Complete Randomized Design (CRD) and the experiment was carried out at Bangladesh Institute of Nuclear Agriculture, Bangladesh Agricultural University, Mymensingh. Drought was imposed at the reproductive stage. where physiological data such as chlorophyll content and photosynthetic rate were recorded. Results: In season 1 and 2, genotypes NERICA mutant (0.99 and 1.62) and Binadhan-13 (6.81 and 2.72) had a lesser relative reduction in chlorophyll content than in the rest of the genotypes. The relative reduction in photosynthetic rate under drought at the panicle initiation stage was lower in genotypes Binadhan-13 (3.62 and 1.87%) than in other genotypes in both seasons. Relative reduction of Photosynthetic rate at flowering under drought as compared to control was lower in genotypes NERICA mutant (3.92 and 7.68%) and Binadhan-13 (13.62 and 13.39%) than all other genotypes in both seasons. Conclusion: Compared to control, relative reduction at 40% FC in the above parameters, Binadhan-13 and NERICA mutant genotypes were classified into drought.