Cowpea (Vigna unguiculata (L.) Walp) Accessions Evaluation for Cercospora Leaf Spot Resistance Under Changing Weather

Abstract

Background and Objective: Cowpea (Vigna unguiculata L. Walp) is considered to be an important food crop in Nigeria. However, its production in commercial quantity is constrained majorly by 64% fungal diseases especially Cercospora Leaf Spot Disease (CLSD). The objective of this research was to evaluate sixty-two cowpea accessions for resistance to Cercospora Leaf Spot Disease (CLSD) and determine their agronomic parameters to identify resistant accessions that could be used as breeding materials for improved cowpea germplasm. The study also aimed to assess the impact of weather conditions on disease incidence and severity. Materials and Methods: In line with this, a study was conducted to evaluate sixtytwo cowpea accessions for resistance to CLSD at the Research Farm, Institute of Agricultural Research and Training, Obafemi Awolowo University, Ibadan, the site is located at (Latitude 07°23'N, Longitude 03°51'E).The trial took place during the dry season (August to November) 2017 and the wet season (May to August) 2018. The cowpea accessions were laid-out in Randomized Complete Block Design with three replications. Data were collected on disease incidence and severity as well as agronomic parameters. Data collected were subjected to Analysis of Variance and means of significant treatments were separated using Duncan's Multiple Range Test at p<0.05. Results: The results indicated that due to emerging weather conditions, the disease incidence and severity were significantly (p<0.05) different for the two seasons and also for the accessions, the disease reaction in the dry season showed that 2 accessions (TVu-9202 and TVU-9276) were highly resistant, 31 were resistant, 23 were moderately resistant and 6 were moderately susceptible. However, in the wet season, 29 accessions were moderately resistant, 32 moderately susceptible and one (IFE BPC) was susceptible based on 0-5 adopted severity scale. Conclusion:Cercospora Leaf Spot (CLS) disease has serious implications on cowpea production and yield based on the prevalent weather condition and the inherent genetic trait. Hence, the observed resistant cowpea accessions found in this study can be further evaluated in different agroecological zones.