Estimation of genetic variability, heritability, and genetic advance for drought-tolerant traits in an F2 mapping population of rice

Abstract

This study aimed to estimate heritability, genetic variability, and genetic advance for eight traits in the F2 segregating population derived from a cross between GNR-6 (susceptible) and NVSR-2272 (tolerant). Initial parental screening for drought-tolerant physio-morphological traits was conducted during summer 2020. The F1 hybrids were developed and selfed in Kharif 2020 to produce the F2 generation. Phenotyping of the F2 mapping population was carried out in summer 2021 at the Regional Rice Research Station, Vyara, Gujarat. The study comprised 190 F2 progenies, with three plants of each progeny grown in pipes. Data were recorded for traits including relative water content, water use efficiency, photosynthesis, stomatal conductance, transpiration, chlorophyll content and grain yield per plant. High genotypic (GCV) and phenotypic (PCV) coefficients of variation were observed for most traits, indicating significant variability within the population. However, traits such as relative water content and photosynthesis showed low heritability and genetic advance, suggesting the predominance of non-additive gene effects and environmental influences. Conversely, high heritability and genetic advance were noted for water use efficiency (73.17%, 50.91%) and transpiration (69.62%, 134.01%), indicating additive gene effects and potential for improvement through selection. Chlorophyll content exhibited high variability but low heritability (19.19%), implying a strong environmental impact. Grain yield per plant demonstrated low heritability (8.08%), suggesting limited scope for direct improvement through selection. The results underline the complexity of trait inheritance in the F2 population, with significant environmental influence on most traits. Traits with high heritability and genetic advance, such as water use efficiency and transpiration, hold promise for breeding programs targeting drought tolerance. These findings provide valuable insights for developing rice varieties with enhanced yield and resilience under water-limited conditions.