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
