EVALUATION OF INSECT PEST TOLERANCE IN ETHYL METHANE SULPOHONATE (EMS) EXPOSED COWPEA (VIGNA UNGUICULATA L.)

Abstract

ABSTRACT

Cowpea [Vigna unguiculata (L.) Walp.] is a widely cultivated legume in the semiarid tropics of Africa and the United States. Low yield of cowpea is often associated with insect pest attacks. This study aimed at evaluating the insect pest tolerance in Ethyl methane sulphonate (EMS) induced cowpea. The seeds were collected at National Centre for Genetic Resources and Biotechnology (NACGRAB). The seeds were planted in 25 kg planting bags at the botanical garden of the Department of Plant Biology, Federal University of Technology, Minna using a Complete Randomized Design (CRD) with 4 replicates. Four cowpea genotypes (Early white, Local variety, IT90K-76 and IT97-556-4) were treated with different concentrations of EMS (0.00%, 0.10%, 0.20%, 0.30% and 0.40%). Control of IT97K-556-4 had the highest plant height at week 20 (70.73 cm), 0.40 % of IT97K-556-4 had the highest number of leaves, it also had the highest leaf width at 0.10 % and highest leaf length at 0.20 % concentration of EMS. The accessions varied considerably in terms of morphological parameters. For insect infestations, the associated insects are Cowpea foliage weevil (Callosobruchus maculatus) and Armyworm (Spodoptera frugiperda). Low insect infestation of 0.20 % concentration of EMS for IT97K-556-4 and Local variety compared to other treatments is an indication of tolerance to the genotypes. For yield parameters, the accessions and concentrations varied considerably. Accession Early white had the heaviest weight of pod and weight of 100 seeds in concentration 0.30 % (2.10 g) and concentration 0.20 % (20.03 g) respectively. Accession Local variety had the best in length of pod (14.70 cm), number of seed per pod (12.33), number of pod per plant (12.33) in control. For proximate composition, control of IT90K-76 genotype had the highest moisture content at concentration 0.30 % (10.78), it had the highest Ash content (5.88), crude fat (4.48) and crude fibre (0.39). Local variety had the highest dry matter and carbohydrate at concentration 0.10 % (94.00) and 0.40 % (70.15). For mineral composition, IT97K-556-4 had the highest sodium, potassium and magnesium at 0.10 % (270 mg /100 g), 0.40 % (710 mg /100 g) and 0.10 % (470 mg /100 g. it can be concluded that there is an indication of induced variability in the crop and has a potential of being selected in crop breeding programs. It is therefore recommended that further studies should be carried out to ascertain the effect of EMS on cytological content and molecular compositions of the genotypes.