Genetic Variability and Association Studies for Morpho-floral Traits in Backcross Introgression Lines of Rice (Oryza sativa L.)

Background: Wild introgressions are pivotal in enriching the genetic diversity of cultivated varieties by introducing novel alleles beneficial for crop improvement. Understanding insights into genetic variability and association studies of morphological and floral traits are crucial for enhancing hybrid seed production in rice. Methods: 290 backcross introgression lines (BC4F2) from inter-specific cross of CRMS 32B (maintainer of male sterile line as low stigma exsertion recipient parent) cv. Oryza sativa with Oryza longistaminata (wild rice as high stigma exsertion donor parent) were assessed for 12 morpho-floral traits. The experiment was laid out in randomized complete block design (RCBD) at Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, during Kharif, 2019. Result: ANOVA results showed significant differences among lines for all examined traits. The phenotypic coefficient of variation (PCV) was slightly greater than genotypic coefficient of variation (GCV) for each trait. High PCV, GCV, heritability and genetic advance as percentage of mean were observed for dual stigma exsertion percentage (DSE%) and total stigma exsertion percentage (TSE%), whereas moderate to high values of these parameters were noted for single stigma exsertion percentage (SSE%), grain yield per plant (GYPP), effective tillers per plant (ETPP) and grains per panicle (GPP) traits. Most traits showed positive skewness, except traits SFP (spikelet fertility percentage), SSE% and TSE%. Most traits recorded leptokurtic kurtosis, whereas plant height (PH), GYPP and TSE% exhibited platykurtic kurtosis. TSE% displayed a highly significant positive association with SSE% and DSE%, while GYPP showed a significant positive correlation with ETPP and GPP, presenting a promising opportunity for simultaneous selection of these traits.