Genetic Variability Studies in a Biparental RIL Population for Blast Disease in Pearl Millet

Abstract

Aim: This study aimed to estimate genetic parameters within a pearl millet population comprising 288 recombinant inbred lines (RILs) of the F7 generation along with two parental lines. The investigation focused on exploring the relationships among 13 quantitative traits and Blast disease score across two environments (ENV-I, ENV-II) as well as in pooled environments. Study Design: Alpha Lattice Design. Place and Duration of Study: Patancheru, Telangana and Vizianagaram, Andhra Pradesh during Kharif, 2023. Methodology:  The RILs used for this current study developed through the single seed descent method at ICRISAT, Patancheru. The genotypes were assessed at ICRISAT, Patancheru, Hyderabad (ENV-I), and Agricultural Research Station, Vizianagaram, Andhra Pradesh (ENV-II). Combined Analysis of Variance, Heritability, Phenotypic Coefficient of Variation (PCV), Genotypic Coefficient of Variation (GCV), Genetic Advance as percent of Mean (GAM), and Correlation studies were performed in R 4.4.0. Results: The analysis identified significant variation in both the quantitative traits and Blast disease scores among the RILs, highlighting the potential for genetic improvement and selection. High heritability coupled with substantial genetic advance was observed for traits such as Plant Height, Number of Tillers, Panicle Length, Thousand Seed Weight, Seed Yield, Harvest Index, and Blast Score across ENV-I, ENV-II and Pooled environments. PCV and GCV were notably high for the Number of Tillers, Number of Productive Tillers, Thousand Seed Weight, Seed Yield, and Blast Score across ENV-I, ENV-II, and Pooled Environments. Seed Yield showed positive and significant correlations with the Number of Productive Tillers, Harvest Index, Plant Height, and Number of Tillers in all environments. Conversely, Blast Score exhibited negative associations with all studied traits across the environments. Conclusion: High heritability coupled with high GAM, along with medium to high PCV and GCV for traits such as plant height, panicle length, seed yield, harvest index, and thousand seed weight, indicates that these traits are predominantly genetically controlled and can be improved significantly through selection, making them valuable for breeding.  Blast disease was negatively correlated with seed yield, thousand seed weight, days to maturity, harvest index, number of leaves, number of productive tillers, plant height, and number of tillers, suggesting that increased susceptibility to blast disease negatively affects key agronomic traits. This implies that genotypes with higher blast disease scores tend to exhibit lower productivity, delayed maturity, and reduced overall plant vigor, making resistance to blast disease a critical factor for achieving optimal crop performance and yield stability.