Evaluation of morphological variations in fifteen traditional yard long bean (<em>Vigna unguiculata</em> L.) accessions in Sri Lanka under organic conditions

The yard long bean, belonging to the family Fabaceae, holds significant popularity as a vegetable crop in Sri Lanka. Several indigenous yard long bean accessions are available in Sri Lanka, and assessing their morphological variability plays a vital role in utilizing the germplasm effectively for future breeding programs. The study focused on characterizing fifteen traditional yard long bean accessions gathered from various locations in Sri Lanka using four qualitative and nine quantitative traits. The study was conducted without using inorganic fertilizer and chemical pesticides. The morphological variation among the accessions was effectively assessed using Principal component analysis (PCA), cluster analysis, 2D scatter plot, and hierarchical dendrogram. Three principal components derived from the nine traits and scored more than one Eigenvalues cumulatively explained 79.31% of the total variance. Pod weight, pod diameter, and pod length contributed to principal component one (PC1), which explained 38.68% of the variance. Cluster analysis identified five morphologically distinct clusters at cluster distance of five. Cluster II comprised the accessions TJ-Rathu and TJ-150 that had the highest mean number of pods per plant, and pod yield (7.84 g and 283.37 g, respectively) at the first three consecutive harvests. TJ-150 recorded the highest pod yield per plant (289.8 g). Pearson's correlation analysis indicated that the number of pods per plant, correlated with the pod yield at 0.05 significance level. The qualitative and quantitative characteristics are expected to be valuable for future breeding programs, facilitating the improvement of yard long beans.