Yield determinants in rice under organic and conventional production systems: Implications for selection strategies

The persistent yield gap remains a major challenge in organic agriculture despite its increasing importance for sustainable food production. The present study compared the performance of 80 diverse rice genotypes (62 landraces and 18 modern varieties) under two contrasting production systems (organic and conventional). The experiment was conducted during the Kharif seasons of 2023 and 2024 using an alpha lattice design (8 × 10) with three replications. Agro-morphological and yield-related traits were analysed through pooled mixed-model analysis of variance (ANOVA), genetic variability parameters, correlation and path coefficient analyses, as well as principal component analysis (PCA). The results revealed significant genotypic variation and differential trait expression between the two production systems, with the relative contribution of agro-morphological traits to grain yield varying between production systems. Integrated analysis of genetic variability, correlation, path coefficient analysis, and principal component analysis identified production system-specific trait combinations associated with grain yield. Under the conventional production system, flag leaf breadth (FLB), number of productive tillers per plant (NPTP), hundred seed weight (HSW), and flag leaf length (FLL) were prominent traits, with strong positive direct effects in path analysis, whereas leaf area (LA), NPTP, HSW, plant height (PH), and days to 50% flowering (DFF) were prominent under the organic production system, also showing positive direct effects in path analysis. Genotypic best linear unbiased prediction (BLUP) estimates identified Ponmani samba (G40), Varakkal (G60), and Sengalapattu sirumani (G49) with the highest yield BLUP estimates under the organic production system, whereas Mani samba (G29), TKM1 (G80), and Bavani (G6) showed the highest yield BLUP estimates under the conventional production system. Milagu samba (G31), Polinel (G39), and Ponmani samba (G40) consistently ranked among the top-performing genotypes based on yield BLUP estimates across both production systems, indicating their potential as breeding materials for further evaluation.