Principal component analysis of morpho-floral traits in Oryza sativa × Oryza longistaminata advanced backcross lines of rice

Abstract

Hybrid rice technology substantially improves the food security of South Asian countries where rice (Oryza sativa L.) is a staple food. Several traits contribute to hybrid seed production efficiency, among which stigma exsertion is crucial for enhancing production by facilitating out-crossing pollination. This study evaluated the variation patterns and relative impact of 12 morpho-floral traits on overall variability in advanced backcross lines derived from crosses CRMS 32B cv. Oryza sativa and Oryza longistaminata. For this study, 290 BC4F2 lines were grown during Kharif 2019 in 3 replications using a randomized complete block design (RCBD). Principle component analysis (PCA) was performed on all traits, and the findings revealed 11 principal components (PCs). Out of 11 PCs, the first five displayed eigenvalues exceeding 1, collectively explaining 78.78% of the total variability. PC1, PC2, PC3, PC4, and PC5 contributed 26.36%, 19.94%, 14.22%, 9.81%, and 8.44% of the variation, with eigenvalues of 3.16, 2.39, 1.71, 1.18 and 1.01, respectively. PC1 was predominantly associated with yield-related traits such as panicle length, plant height, grain yield per plant, grains per panicle, and effective tillers per plant. On the other hand, PC2 was mainly associated with outcrossing-related floral traits such as total stigma exsertion percentage, dual stigma exsertion percentage, and single stigma exsertion percentage. However, PC3 and PC4 were associated with both floral and yield-related traits, i.e., days to 50% flowering (DF), days to maturity (DM), plant height (PH), effective tillers per plant (ETPP), spikelet fertility percentage (SFP), grain yield per plant (GYPP) and grains per panicle (GPP). Therefore, PC1, PC2, PC3, and PC4 were major contributors to rice hybrid seed production.