Evaluation of cowpea (Vigna unguiculata (L.) Walp genotypes for response to wilt disease caused by Fusarium oxysporum f.sp. tricheiphilum

Abstract

Wilt disease caused by Fusarium oxysporum f. sp. tracheiphilum (Fot), is a primary constraint to global cowpea production. It is a systemic disease which impairs water absorption and translocation processes leading to death of infected plants. This study aimed to evaluate 11 cowpea genotypes for sources of resistance to Fusarium wilt. The experimental pots were inoculated with 3 g of wheat seeds which served as inoculum carrier. Disease severity was evaluated on a six-point scale which ranged from mild to very severe wilting. Area under disease progress curve (AUDPC) was determined using severity values. Data were collected on growth, yield, and disease incidence. Statistical analysis was done using analysis of variance (ANOVA) and means separated with Duncan Multiple Range Test (DMRT) at p<0.05.There was significant (p<0.05) difference among the genotypes on the incidence and severity of Fusarium wilt disease. AUDPC values showed that 27.3, 45.5 and 18.2% of the genotypes were resistant, moderately resistant and susceptible, respectively. Three genotypes, IT07K-282-10, IT99K-573-11 and IT98D-610 were resistant to Fusarium wilt disease in this study, while genotypes IT07K-297-13 and Ife brown control were susceptible and highly susceptible, respectively. Two resistant genotypes, IT96D-610 and IT07K-230-2-9, with low severity values had the highest yield of 2.66 and 2.74 tones/ha^-1 and these will be useful to breeders for improvement of the low yielding types. These resistant genotypes identified in this study could serve as sources of genes in breeding for resistance to cowpea wilt disease.