Evaluation of Morphological Diversity in Vegetative Growth Parameters of Selected Cowpea Genotypes

Abstract

Cowpea genotype selection rvith appropriate ve-eetatil.e gro'wth traits is a basic necessity for the breeding of improved cowpea varieties. The main objective of this research was to evaluate the rnorphological diversity in vegetative growfh parameters of selected cowpea genor'?es. Twenty-two cowpea genorypes {Cp 32, ANKCM 20-4, CP 169, ANKCA.{ 2A-T, CP IO4, ANKCM ]4-2, CP ]77, C[' ]6, CP 5A, CP ]g5, CP ]73, ANKCv{ 3A-3, CP 2], CP 347, ANK(:M 2O-2, Cf' 246, ANKCM I4-], CP ]58, CP 39, ANKCI|{ I3-4 and improved genotypes l)hau,alu and Warunl) were planted in a Randomized Cornplete Block Design (RCBD) with three replicates. Moqphological traits including plant height (PH), nunber of primary branches (pB), mrmber of leaves (NL), leaf area (LA) and canopy width (CW) were recordecl at four r.veeks afterplanting (4 WAP) and six weeks after planting (6 WAP). Hierarchical clusrer analysis r,vas conducted and a dendrogram was constnrcted using Minitab version l7 to visuali zethe genetic relationships amon-q the genotypes. Results revealed si-eniticant differences (p < 0.05) among the genotypes screened for all the measured traits. The tallest plants were found in genotype f)hau,ctla QA.g4 + 0.45 cm), while the shortesr rvas recorded in (:P 50 (8.1s + 0-55 cm). The highest number of primary branches was found in Dhav'ala (3.70 + 0.21) and Wanmi (3.33 + 0.12) while mosf of the other genorypes were less branched. Leaf area was quite variable with ANKCM l4-) (134.57 + l.3l cm2) and ANKCM I4-1 (1-11.8 + 30.4 cmr) recording the highest values, indicating robusf vegetative growth. Cluster analysis of morphological traits had distinct grouping tendencies. Genotypes CP 16, Cp lgs, cp 39, Cp 173, cp I7T andANKCM 4l_l fonned a compact cluster, indicating close morpholo-eical similarity and potential genetic relatedness. These findings exhibit significant diversity among the evaluated cowpea genotypes and identifli promising lines with desirable vegetative gowth characteristics for use in future breedinq and crop improvement programs i1 Sri Lanka