Assessment of the Effect of Fungal Parasites and Callosobruchus maculatus Fab. on the Physiological and Biochemical Parameters of Cowpea (Vigna unguiculata (L.) Walp.) Seeds in Côte d’Ivoire

Cowpea (Vigna unguiculata (L.) Walp.), is a legiminous plant grown in the tropical regions of Africa. It is used in food and feed because of its high protein content. However, its storage and preservation are affected by numerous abiotic and biotic constraints including fungi and insects. This work was initiated with the aim of sanitary analyzing, physiological and biochemical state of Cowpea seeds, in order to seek and remove the constraints related to their viability. Purity, contamination and germination tests were carried out. Different culture media (PDA and blotting paper) were used for the tests. Seed viability by area of attack by Callosobruchus maculatus, main pest of Cowpea stocks, was also tested. The biochemical compounds of the seeds were assayed. The results indicated that the purity of the Cowpea seeds collected from the different markets of Abidjan was satisfactory overall, with a rate of more than 95% recorded. In contrast, the seeds were susceptible to attacks by fungal microorganisms and insects. Thus, two fungi were isolated and purified. Macrophomina phaseoli species roved to be harmful to Cowpea seeds stored. These fungi prevent seed germination and degrade their biochemical compounds. Also, perforation of seeds at the hilum by Callosobruchus maculatus also prevents germination. Macrophomina phaseoli and Callosobruchus maculatus are real constraints of Cowpea during storage.