Determination of Correlation Among Agronomic Traits of Selected Cowpea Genotypes

Abstract

Cowpea (l'igna unguiniata L. Walp.) is a widely cultivated -erain legurne in tropical and subtropical regiotrs of the u'orld due to its nutritional ancl economic value. Improvement of coi.vpea yield demands comprehensive kerou.ledge of relationships among the key agronomic traits. This study was carried out to deterniine the correlation among the vegetative, flowering and yield related traits of selected cowpea genotypes. The experiment was conducfed from 08tl' of July to October 2025 at the Faculty of Technology experimental farm, Eastern University, Sri Lanka. Twenty Trvo genotypes (cP 32, ANKCM 20-4, cP 169, ANK(:M 20-r, cp r04, ANKCM r4- 2, (P 177, CP ]6, CP 5A, (P 195, (P ]73, ANK(:M 2O-3, CP 2i, CP 247, ANKCM 20-2, (:P 246, ANK{:M I4-1, cP l5s, CP 39, ANKC.M I3-4 andimprovecl genotypes Dhuu'ala and ll/urunl) were evaluated using a randornized complete block clesign rvith three replicates. Each plot consists of 20 co\,\ipea genot]?es. Plant heights, number of leaves, primary branches and leaf area were recorded at four rveeks after planting and six weeks after planting. Days fo flowering. number of pods per plant, number of seeds per pod. 100-seed weight, grain yield. biomass yield and harvest index were recorded. The R Studio 4.5.0 version was used for correlation anaiysis. A moderate positive correlation (r : 0.46) was found befween plant height and primary branches indicating that taller genotypes are m(:ie branched. The correlation betrveen plant height and leaf area was rnoderately negative (r: -0.31). Pod length and 100-seed rveight also shou'ed a strong positive correlation (r:0.81) while larger pods contributed to heavier seeds. Horvever seeds per pod r.r,ere found to be moderatelv negatively correlated with the 100-seed weight (r : -0 55) indicating a partial tradeoff between seed number and size. Biornass yield and harvest index were positively correlated at a moderate rnagnitude suggesting effective biomass allocation in higher yielding genot)?es. In general 1O0-seed weight, pods per plant and vegerarive vigor were the important contributing traits toward yield thus reflecting their use in breeding high yielding and stress-resistant coupea varieties for Sri Lanka.