Comparative Assessment of Early Seedling Vigour in Rice Genotypes under Laboratory and Direct-seeded Field Conditions

Abstract

Early seedling vigour is vital for successful crop establishment, weed suppression, and yield potential in direct-seeded rice (DSR) systems. This study evaluated 86 rice genotypes for vigour-related traits under both laboratory (paper towel method) and dry DSR field conditions. Traits assessed on 14th day after sowing included germination percentage, shoot and root length, total seedling length, dry weight and seedling vigour indices (SVI I and II). Significant genetic variability was observed across all traits and conditions. Genotypes exhibited greater shoot elongation in laboratory conditions and higher biomass under field conditions, indicating environment-specific trait expression. Using the cumulative vigour response index (CVRI) genotypes such as Varalu, Anjali, SMB 3, Arakalu and Warangal Samba were identified as highly vigorous across environments. Strong positive correlations were found among key traits especially between total seedling length and SVI I and between dry weight and SVI II. Principal component analysis showed PC1 accounted for 44.2% of total variation, with most vigour traits contributing positively. This integrated phenotyping approach revealed substantial genetic variation for early seedling vigour, supporting the selection of genotypes with rapid early growth and biomass accumulation, essential for improving establishment and performance in DSR systems.