Evaluation of Cowpea (Vigna unguiculata L.) Genotypes’ Growth and Yield Performance and Resistance to the Cowpea Seed Beetle, Callosobruchus maculatus F.

The search for resistant cowpea (Vigna unguiculata (L.)) Walp. genotypes against the cowpea seed beetle Callosobruchus maculatus F. (Coleoptera: Chrysomelidae) in order to minimize the use of synthetic insecticides due to problems associated with their use led to field and laboratory experiments to evaluate the growth and yield of 10 cowpea genotypes on the field and their responses to the insect in the laboratory. A randomized complete block design with three replications and a completely randomized design with four replications were used for the field and laboratory experiments, respectively. The study was undertaken at Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana from the period August 2016 to February 2017. The cowpea genotypes were Asontem, Sanzisanbili, Hans Adua, Zamzam, Nketewade, Videza, IT97K-819-132, Agyenkwa, Bengah and Bianga. The results of the field experiment showed that there were significant differences among the cowpea genotypes in all the growth and yield parameters evaluated. Asontem, Hans Adua, Zamzam, Videza and Bianga produced significantly (P< .05) taller plants at maturity. Nketewade produced the highest grain yield (466.1 kgha-1) whiles Sanzisanbili, Hans Adua, Zamzam, Videza, Agyenkwa and Bengah recorded the lowest grain yields. The grain yield ranged from 75.4 to 466.1 kgha-1. Results from the laboratory experiment showed that Videza supported the least number of F1 progeny, prolonged the development period of C. maculatus and suffered the least storage weight loss. Videza was thus the only genotype that showed moderate resistance to C. maculatus whiles the other genotypes were either susceptible or highly susceptible.