Effect of Drought Stress on Morphological and Physiological Traits at Panicle Initiation Stage in Six Rice Genotypes (Oryza sativa L.)

Drought is one of the most prevalent forms of abiotic environmental stress that reduce crop productivity. A pot experiment was performed in two Aman seasons under drought (40% field capacity, FC) and control (100% field capacity, FC) irrigations to study drought tolerance mechanism(s) based on morphological and physiological traits in six aromatic rice genotypes. Twelve treatments (6 genotypes × 2 irrigations) were arranged in Complete Randomized Design and experiment was carried out at Bangladesh Institute of Nuclear Agriculture, Bangladesh Agricultural University, Mymensingh. In the experiment, drought was imposed at panicle initiation stage where morphological and physiological data were recorded. Important morphological (stem and root dry weight) and physiological (photosynthesis and chlorophyl content) attributes were significantly (P>0.05) decreased at 40% FC in both the years. Compared to control, relative reduction at 40% FC in above parameters, genotypes were classified into tolerant (Binadhan-13 and NERICA mutant) and sensitive (RM-100-16, Ukunimodhu, Kalizira, and BRRI dhan34) categories. Tolerant genotypes had smaller reduction in shoot and root dry mater (av. 7.73 and 5.56 %, respectively) than sensitive ones (av. 19.32 and 21.80%, respectively). Low reduction percentages of the traits under drought stress to that of the control discriminated Binadhan-13 and NERICA mutant genotypes consistently as drought tolerant.