Assessment of variation in the agronomic traits of wild cowpea (Vigna unguiculata (L.) Walp.) subspecies under a rainforest agro-ecology in Nigeria

Wild relatives of crop species are often sources of genes for diseases and insect pest resistance, increased yield, improved quality, earliness and wide adaptation. Wild subspecies of cowpea that are cross-compatible with cultivated varieties have great potential as an additional source of useful germplasm for cowpea improvement. In this study, the variations in the growth and agronomic traits of 20 cowpea accessions from the subspecies: stenophylla, dekindtiana and tenuis were evaluated in a randomized complete block design with four replications. Highly significant variations were observed among accessions for all traits measured. There were variations for same traits among the accessions from the subsp. dekindtiana whereas, the accessions from the subspecies stenophylla and tenuis showed similar performance. Accession TVNu1839 from the subsp. dekindtiana showed an outstanding performance in number of days to flowering and pod ripening, number of main branches at flowering, number of seeds per pod, 100 - seed weight and total seed weight which implies that the accession has a high yield potential. Therefore, the subsp. dekindtiana may be a useful source of genetic variation needed for the development of improved cowpea varieties for resource poor farmers at a relatively low expense, since it has been established that they are cross-compatible with the cultivated varieties. Highly significant (P < 0.001) and very strong correlation coefficient among traits, may be useful as selection index and can be exploited in cowpea improvement programmes. These results confirm that wild cowpea subspecies have the potential to enhance cowpea gene pool.