Genotypic Variation and Trait Associations for Yield and Yield-Related Traits in Soybean (Glycine max L.) under Different Sowing Dates

Abstract

Soybean (Glycine max L.) performance is strongly influenced by sowing time and genotype, and identifying the most productive combination is important for stable yield production. The present study evaluated three soybean genotypes (Faisal Soya, AARI Soya and NARC-21) under three sowing dates (15 August, 1 September and 15 September) during the Kharif season of 2024 at the experimental area of the Oilseeds Research Institute, Agricultural Research Center, Tandojam. The experiment was conducted in a factorial randomized complete block design with three replications. Nine agronomic traits were recorded and analyzed using analysis of variance, mean comparison, broad-sense heritability and phenotypic correlation. Sowing date significantly affected branches plant⁻¹, pods plant⁻¹, plot seed yield (g) and seed yield (kg ha⁻¹), whereas days to 1st flowering, germination %, days to 90% maturity, plant height (cm) and seeds pod⁻¹ were not significantly affected by sowing date. Genotype effects were highly significant for germination %, branches plant⁻¹ and plot seed yield (g), while the sowing date × variety interaction was significant only for days to 1st flowering. Among sowing dates, 15 August produced the highest plot seed yield (326.56 g) and seed yield (805.78 kg ha⁻¹). AARI Soya had the highest mean germination (74.89%) and plot seed yield (297.00 g), whereas Faisal Soya recorded the highest mean number of branches plant⁻¹ (3.89). Broad-sense heritability ranged from 14.98% for plant height to 96.35% for germination, with high heritability for germination, branches plant⁻¹ and plot seed yield. Phenotypic correlation analysis indicated that plot seed yield was strongly and positively associated with pods plant⁻¹ (r=0.683**) and branches plant⁻¹ (r=0.612**), while seed yield was strongly associated with plot seed yield (r=0.918**), pods plant⁻¹ (r=0.641**) and branches plant⁻¹ (r=0.578**). The results demonstrate that timely sowing, particularly 15 August under the tested conditions, and selection for productive branching and pod formation can contribute to improved soybean productivity.