Preliminary assessment of growth and seed production in advanced cowpea (Vigna unguiculata L. Walp.) lines infected with Cucumber mosaic virus

Abstract

Cowpea (Vigna unguiculata L. Walp) plays a prominent role in the diet of millions of people in developing countries. It is also fed to livestock and contributes substantially towards increased soil fertility. In spite of its numerous economic importance yield is hindered by several pests. Cucumber mosaic virus (CMV) is one of the viruses of economic importance on cowpea. Therefore, 23 advanced cowpea lines were screened for resistance to CMV. Two trials were conducted in a glasshouse using completely randomised design with three replications. Cowpea plants were infected with CMV by sap inoculation at 10 days after sowing. Data were collected on plant growth and seed production. The data were subjected to analysis of variance (ANOVA) and significance of the treatment means was determined at p≤0.05. Cluster analysis was performed to determine the relationships in growth and seed yields based on Unweighted Pair-Group Method with Arithmetic averages (UPGMA). The cowpea lines 07K-230-2-5, 07K-291-69, 12K-261 and 12K-515 exhibited significant (p<0.05) earliness to flowering with outstanding pod and seed production. These cowpeas flowered at 41-49 days after sowing (DAS), produced a maximum of three pods per plant and between seven and 10 seeds per pod. Cluster analysis indicated that 07K-230-2-5, 07K-291-69, 12K-261 and 12K-515 belonged to the same cluster, indicating genetic similarity. The four (07K-230-2-5, 07K-291-69, 12K-261 and 12K- 515) cowpea lines probably contained CMV resistant genes which could be explored for breeding purposes.