Exploring Genetic Variability in Rice for Yield Improvement under Low Phosphorus Soil Conditions

Phosphorus (P) is an essential macronutrient for all living organisms. P deficiency in soils is a major limiting factor for crop growth in rice and reduces yield. Understanding genetic variability for low P tolerance is crucial for improvement of rice genotypes for this stress. This study was conducted under low soil P and normal conditions to evaluate genetic variability in yield and its associated traits among rice genotypes. The experimental material consists of 91 F2:3 mapping population along with two checks, planted in a low P and normal plot at ICAR-IIRR, Hyderabad. Traits assessed included days to 50% flowering, plant height, total number of tillers, number of productive tillers per plant, flag leaf length, flag leaf width, panicle length, total number of grains per panicle, spikelet fertility, single plant yield, shoot length, root length, root volume, dry root weight, dry shoot weight and root to shoot ratio. ANOVA analysis suggested, mean sum of squares due to test genotypes were significant (p<0.01) for most of the traits under study. Plant height, number of tillers per plant, number of productive tillers per plant, flag leaf length, number of grains per panicle, spikelet fertility, single plant yield, shoot length, root volume, shoot dry weight, root dry weight and root to shoot ratio possessed high GCV and PCV values under low P condition. Genetic advance as per cent of mean for all traits possessed high genetic advance as per cent mean except for days to 50% flowering which showed medium GAM under low P condition. The genotypes showed varied response to genetic variability, heritability and genetic advance as per cent mean for days to 50% flowering (low), plant height (high), number of productive tillers per plant (high), panicle length (medium to high), flag leaf length (high), flag leaf width (medium to high), number of grains per panicle (high), spikelet fertility (high), single plant yield (high), root volume (high), shoot dry weight (high), root dry weight (high) and root to shoot ratio (high) under low P condition. This study identified these traits with high genetic variability and heritability, which are useful for developing P efficient rice cultivars and selection based on these traits would improve the rice for low soil P tolerance.