Influence of support system on country bean production during summer season

Abstract Country bean ( Lablab purpureus L.) is a valuable leguminous vegetable crop with nutritional and economic significance in tropical and subtropical regions. The present study was to evaluate the performance of three photo-insensitive country bean genotypes, namely Sikribi Sheem-1 (V1), Sikribi Sheem-2 (V2) and SB003 (V3), which were grown under three different support systems called horizontal trellis (S1), vertical trellis (staking, S2) and sloped trellis (A-shaped trellis, S3). The results showed that internode length varied significantly among treatments, with Sikribi Sheem-1 under vertical trellis (17.57 cm) exhibiting the greatest length, indicating increased canopy spread and photosynthetic efficiency. However, other vegetative features showed insignificant variation. Flowering occurred earliest in Sikribi Sheem-1 under an A-shaped frame (40.00 days) and latest under a horizontal trellis (45.67 days). Genotype support interaction significantly influenced pod number per plant and pod yield. The highest values were recorded in Sikribi Sheem-1 under vertical trellis (288.83 pods per plant and 1.34 kg per plant), whereas SB003 under staking and A-shaped frame produced the longest pods (9.93 and 9.80 cm) and highest dry matter (22.30%). Pearson correlation analysis revealed strong positive correlations among pod yield, number of pods per plant, number of branches per plant, and pod morphology, highlighting the critical factors for high productivity. Then, Principal Component Analysis (PCA) split growth, physiological, and yield-contributing traits into distinct groups, explaining 62.8% of total variation, whereas heatmap clustering illustrated co-association patterns among traits and treatments. These findings demonstrate that Sikribi Sheem-1 with vertical trellis or staking is the most effective combination for optimizing plant architecture, enhancing assimilate partitioning, improving canopy efficiency, and providing an effective, low-cost strategy to maximize yield and pod quality of climbing country bean under summer cultivation.