Tolerance levels of cowpea (Vigna unguiculata L. Walp) cultivars to cucumber mosaic disease in Minna, Northern Nigeria

Abstract

Cowpea (Vigna unguiculata) is a major legume food source for millions of people and feed for livestock in sub- Saharan Africa, Nigeria inclusive. It is also incorporated into traditional cropping system owing to its ability to fix atmospheric nitrogen for soil fertility improvement. Despite its numerous uses, cowpea productivity is threatened by Cucumber mosaic virus (CMV) disease. Therefore, eight cowpea cultivars (IT07K-243-1-2, IT07K-298-15, IT07K- 303-1, IT08K-126-19, IT08K-150-12, IT08K-180-11, IT08K-193-14 and IT10K-837-1) were tested for CMV disease resistance in Minna, northern Nigeria during the 2016 cropping season. The eight cultivars which constituted the treatments were evaluated as infected and uninfected (control) using randomised complete block design with three replications. Cowpea plants were infected with CMV through mechanical inoculation at 10 days after sowing. All the CMV-infected plants exhibited mosaic and leaf curling symptoms. Disease incidence varied from 81.7 to 96.3 % at 2 weeks after inoculation. The highest number of leaves per plant (112), branches (5) and pod number (2) were observed in the infected plants of IT10K-837-1. On the other hand, the diseased plants of IT07K-243-1-2 produced the highest pod (4.1 g) and seed weight (4.0 g) per plant. Therefore, the IT10K-837-1 could be regarded as the best cultivar for hay and fodder production. Conversely, IT07K-243-1-2 was identified as the promising cultivar for seed production. These two cowpea cultivars could be explored for breeding CVM tolerant cowpea germplasm in order to reduce malnutrition and food insecurity.