Characterization of Genetic Variability in Early Seedling Vigour Traits of Rice (Oryza sativa L.) under Laboratory Conditions

Abstract

Early seedling vigour (ESV) is a key determinant of successful establishment in direct-seeded rice (DSR), where rapid germination and early growth uniformly helps to suppress weeds, improve crop stand, and ultimately support higher productivity. The present study evaluates the characterization of Genetic Variability in Early Seedling Vigour Traits of Rice (Oryza sativa L.) under Laboratory Conditions. In this study, 180 rice genotypes were assessed under laboratory conditions to quantify genetic variability in seedling traits and vigour indices and to determine their contribution to ESV through genetic parameter estimation. Analysis of variance showed significant differences among genotypes for all measured traits, indicating substantial genetic diversity and confirming the presence of a broad genetic base suitable for selection. The phenotypic coefficient of variation (PCV) slightly exceeded the genotypic coefficient of variation (GCV) for most traits, suggesting limited environmental influence on trait expression. Broad-sense heritability estimates were consistently high (>80%), and most traits exhibited moderate to high genetic advance as a percentage of mean (GAM), reflecting the predominance of additive gene action and the potential for effective genetic improvement. Shoot length, total fresh weight of seedling, rate of germination, and Seedling Vigour Index II (SVI II) were identified as strong and reliable selection indicators for enhancing ESV. These findings highlight the importance of multi-environment phenotyping for identifying priority traits in breeding rice better suited to DSR cultivation. By determining key contributors to early seedling vigour, this study provides practical trait-based indices to improve crop establishment and productivity in resource-efficient rice production systems.