Expression of Metrical Traits on Yield and its Components in Different Accessions of Soybeans (Glycine max (L.) Merrill)

Abstract

Low productivity in soybean (Glycine max L. Merrill) across Nigerian farming systems remains a persistent challenge, driven in part by the limited use of genetically diverse and locally adapted cultivars. This study evaluated the expression of yield-related traits among ten soybean accessions obtained from the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, to identify superior genotypes and inform selection strategies for yield improvement. The experiment was conducted in a Randomized Complete Block Design (RCBD) with three replications at the research farm of Adekunle Ajasin University, Akungba-Akoko, Ondo State, Nigeria. Data were collected on nine quantitative traits: plant height, number of main branches, days to first flowering, days to maturity, pod length, pods per plant, seeds per pod, 100-seed weight, number of seeds per plant, and seed yield per plant. Analysis of variance revealed significant genotypic effects (p ≤ 0.05) for most traits, except for the number of main branches and pods per plant. Accession V9 recorded the highest seed yield per plant (16.14 g), pods per plant (23.80), seeds per pod (3.53), and number of seeds per plant (84.71), while V5 produced the heaviest 100-seed weight (22.27 g). Genetic parameter estimates showed that days to first flowering had the highest broad-sense heritability (92.89%), followed by pod length (72.08%) and seeds per pod (70.58%), all with moderate to high genetic advance. Pearson's correlation analysis revealed highly significant positive associations between seeds per pod and number of seeds per plant (r = 0.93), number of seeds per plant and seed yield per plant (r = 0.87), and seeds per pod and seed yield per plant (r = 0.78). These findings identify V9 as the most promising accession for yield improvement and recommend seeds per pod and number of seeds per plant as the most reliable indirect selection criteria for advancing soybean yield within this germplasm.