Unraveling Source–Sink Dynamics Governing Yield in Soybean Using Correlation and Path Coefficient Analysis across Contrasting Moisture Regimes

Abstract

Aims: This study analysed source-sink relationships governing seed yield in soybean under contrasting moisture regimes using correlation and path coefficient analyses. Study Design: A randomised block design with two replications was used. Place and duration of study: The study was conducted at the ICAR-National Soybean Research Institute, Indore, during 2023 and 2024. Methodology: Eighty-six soybean genotypes from an advanced recombinant inbred line population were evaluated for morphological, yield-related and physiological traits. Phenotypic correlations were estimated to assess trait associations, and path analysis partitioned correlations into direct and indirect effects on seed yield per plant. Results: Analysis of variance indicated significant genotypic differences for most traits across years. Seed yield per plant was positively associated with pod weight per plant, number of pods per plant and biomass per plant. Under moisture stress, canopy temperature depression, SPAD chlorophyll content and delayed leaf senescence showed favourable associations with productivity, whereas stem reserve mobilization was negatively associated with seed yield. Path analysis identified pod weight per plant as having the highest positive direct effect on seed yield. Plant height and delayed leaf senescence also showed positive direct effects, while biomass per plant had a negative direct effect despite its positive correlation with yield, indicating an indirect contribution through yield components. Conclusion: Soybean yield improvement under variable moisture conditions was closely linked with sink-related traits and assimilate partitioning. Pod weight per plant, pod number, plant height and delayed leaf senescence may be useful selection criteria for improving yield and stress adaptation.