Genetic Variability, Heritability, and Genetic Advance for Early Seedling Vigour Traits in Rice (Oryza sativa L.) under Laboratory Screening for Wet Direct Seeded Conditions

Early seedling vigour (ESV) is a critical trait in rice, particularly under wet direct-seeded cultivation systems, as it promotes rapid crop establishment, suppresses weed competition, and improves resource use efficiency. Understanding the genetic basis of ESV traits is essential for identifying potential genotypes suitable for direct-seeded rice (DSR) cultivation. The present study was undertaken to evaluate genetic variability, heritability, and genetic advance for ten early seedling vigour traits under controlled laboratory conditions using 64 diverse rice genotypes. Laboratory experiments were conducted during rabi 2024-2025 at Sri Venkateswara Agricultural College, Tirupati, Andhra Pradesh, India following a completely randomized design and analyzed using R programming. The ten traits studied include First count of germination, final count of germination, rate of germination, root length, shoot length, seedling length, root to shoot ratio, seedling dry weight, seedling vigour index 1 and seedling vigour index 2. Statistical analysis indicated significant genetic variability among genotypes for all traits. High heritability coupled with genetic advance were observed for first count of germination, final count of germination, root length, shoot length, seedling length, root to shoot ratio, seedling dry weight, seedling vigour index I and seedling vigour index II, indicating predominance of additive gene action and suggesting these traits can be effectively improved through direct selection. Genotypes such as NLR 3091, NLR 3118, NLR 3367, and NLR 3773 consistently exhibited superior performance for multiple ESV traits and may serve as valuable genetic resources in breeding programs targeting direct-seeded rice systems. The findings highlight the importance of selecting traits with high heritability and genetic advance to enhance genetic gain and yield potential under DSR conditions.