Trait syndromes governing rice genotypes adaptation and productivity under direct-seeded systems

In the context of declining water availability and rising labour costs, direct-seeded rice (DSR) is increasingly promoted as an alternative to puddled transplanted rice (PTR). We hypothesised that rice genotypes differ in their adaptation to DSR and PTR through coordinated trait combinations involving root growth, biomass accumulation and assimilate partitioning. Eight rice genotypes were evaluated under DSR and PTR during the Kharif seasons of 2023 and 2024 at Punjab Agricultural University, Ludhiana. The DSR accelerated crop phenology by 3–6 days, increased root mass density by 22–26% and enhanced early tillering, reflecting rapid establishment under aerobic soil conditions. In contrast, PTR produced taller plants, greater stem strength and marginally higher grain yield through improved reproductive allocation. Regression analysis showed that grain yield was jointly governed by dry matter accumulation and harvest index, explaining 75.1% of yield variation. Principal component analysis revealed contrasting trait associations between establishment methods, with DSR aligning more closely with physiological growth traits and PTR with structural and partitioning-related traits. Genotypes PR 132, PR 131 and PR 126 consistently exhibited superior productivity and adaptability across establishment methods. Overall, the study demonstrates that successful adaptation to DSR depends on integrated trait combinations rather than isolated traits, providing a basis for developing resource-efficient rice genotypes under water-limited production systems.