Root Development and Anti-Oxidative Response of Rice Genotypes under Polyethylene Glycol Induced Osmotic Stress

Osmotic stress is a kind of stress which is directly or indirectly related to all other abiotic stresses. Four rice varieties namely Binadhan-11 (with SUB1 gene), BRRI dhan52 (with SUB1 gene), Binadhan-7 and BRRI dhan71 were used to study the variation in root development and anti-oxidative response under osmotic stress conditions. Osmotic stress was induced by applying polyethylene glycol (4% PEG) in hydroponic solution. Treatment was given at the panicle initiation stage and leaf samples were collected at fourteen days after treatment to estimate antioxidant response in terms of ascorbate (APX) and peroxidase (POD) enzymatic activity. Roots were destructively harvested at 16 days after the stress imposition. The tested varieties showed significant differences in antioxidant responses under the stress condition such as high APX and POD in Binadhan-11 and BRRI dhan52. Significant injury at the 4ᵗʰ leaf position (the youngest leaf was the reference) was observed at 8 and 12 days after the treatment. Number of live leaves, shoot dry weight, density of second order lateral roots, number of phytomer (Pr) and total roots, number of roots at Pr2, main axis diameter at Pr1, main axis length at Pr1 varied significantly among the varieties × treatment combinations. Binadhan-11 and BRRI dhan52 showed comparatively higher osmotic stress tolerance compared to the other two varieties without SUB1 gene, viz., Binadhan-7 and BRRI dhan71. The varieties BRRI dhan52, and Binadhan-11 showed greater capacity to withstand osmotic stress can be further used to develop stress tolerant variety.