Effect of Bacterial Flora on the Viability of Cowpea Seeds Sold in Port Harcourt

Microbial contamination of plants as well as products from plants have become major concern to the public. Contamination of plants could lead to deterioration of the plants including their product thereby altering the nutrient composition of the expected plant product and also presents health hazards if foods from these plants are consumed without much preparation. In Nigeria, cowpea is an important leguminous plant that offers so many forms of delicacies and very rich in protein. The viability and bacterial flora of two cowpea varieties- IT/2246 (brown) and IT/84e (white) purchased from Mile 1, Mile 3, Town market and Rumuokoro market were investigated in the Department of Plant Science and Biotechnology, Rivers State University for proper identification. The cowpea seeds were sorted according to size and wholesomeness. Invitro bacterial assessment of the cowpea seeds was carried out and the bacterial isolates were identified using standard microbiological methods. Viability was done invitro using the cotton wool. Sizeable cotton wool in Petri dishes was dampened in 5ml of distilled water and the different cowpea seeds placed on them. The different sizes and colour of the seeds were placed on the petri dishes. Radicle and plumule lengths were measured for 14days. Bacillus cereus, Bacillus subtilis and Staphylococcus aureus were the bacterial isolates identified. The viability test showed that the radicle length of the big brown, big white, small brown and small white cowpea seeds were 5.12±2.57, 4.75±4.08, 5.66±3.94 and 8.13±3.61 cm for the sample from Mile 1 market. The plumule length of cowpea ranged from 6.91±5.27 to 12.44±5.62, 6.58±2.72 to 9.04±4.9, 4.32±4.29 to 9.15±4.1, and 5.67±5.24 to 10.14±5.4 cm for the Mile 1, Mile 3, Rumuokoro and Town market cow pea samples, respectively. The growth rate of the big brown cowpea, small brown cowpea, big white cowpea and small white cowpea in season one ranged from 40% to 93%, 33% to 73%, 20% to 47% and 40% to 47%, while in season two, 80% to 87%, 73% to 100%, 53% to 73% and 73% to 80% were recorded. The bacterial isolates identified could be pathogenic if food is not properly prepared. Poor pre-harvest seed management practices, poor storage condition and handling processes after harvest could be responsible for the variation in viability.