Response to direct selection for grain yield in interspecific population of oryza sativa ir58025b x oryza meridionalis ng., mapping population under irrigated and stress conditions

Rice (O. sativa L.) is one of the world’s most important crops, particularly in Asia, but increasingly in Africa and Latin America as well. It is one of the important food crops drastically affected by raise in global temperature and has an impact throughout worldwide on people who depend on rice production for their livelihoods and food security. The objective of this study was to evaluate the effectiveness of direct selection for grain yield under heat and irrigated conditions. 274 BC2F6 BILs were derived from a cross between Oryza sativa IR58025B and Oryza meridionalis Ng. (2n = 24, AA), a heat tolerant wild species to evaluate 18 yield and its related traits and for heat tolerance under irrigated and stress conditions. Analysis of variance and genetic estimates indicated there is substantial genetic variation among progenies under both stress and control conditions. The genotypic coefficient of variation ranged from 1.57 for canopy temperature to 77.29 for line yield per plot, whereas, the phenotypic coefficient of variation ranged from 4.31 for panicle temperature to 91.68 for spikelet fertility. The GCV ranged from 6.35 (panicle length) in control to 77.29 (line yield) in stress condition, the PCV ranged from 9.71 (panicle length) to 93.20 (line yield) in stress condition. Further, for physiological traits like flag leaf temperature, panicle temperature, canopy temperature and leaf area index the GCV ranged from 1.57 (canopy temperature) to 17.13 (leaf area index) in stress, the PCV ranged from 1.84 (panicle temperature to 27.05 (leaf area index) in stress. Broad sense heritability estimates varied from 0.34 (panicle temperature) to 0.86 (plant height) in control condition, and 0.12 (canopy temperature) to 0.77 (Days to 50% flowering) in stress condition. Hence, this species can be a novel source of natural genetic variation for the improvement of rice and simultaneously help in expansion of the cultivated gene pool of O. sativa.