Reaction of cowpea genotypes to the root knot nematode, Meloidogyne incognita


  • T. Olowe


Seventy cowpea genotypes were evaluated in two different screen-house pot experiments for their reaction to the rootknot nematode, Meloidogyne incognita host race 4. The known resistant cv. New Era (Acc 64298) and the susceptible cv. Ife Brown (Acc 73001) were included as controls. Based on reproduction, root gall and egg mass indices of the nematode, five genotypes [Vita 3, Acc 64298 (cv. New Era), 82D4532CIT’85, IT89KD-288 and TVX2724-01F], showing reproduction factors (RF) of 0.5-0.8, reproduction indices (RI) of 6.7-8.4, gall numbers (GN) of 4-8, gall indices (GI) of 2, egg mass numbers (EN) of 3-6, egg mass indices (EI) of 2, and root galling of 2-5%, were considered resistant. None of the resistant genotypes was superior to the standard control resistant cv. New Era. Two genotypes, IT8D-12228-10 and IT96D-733, with RF of 2.3 and 3.2, RI of 20.1 and 21.4, GN of 6 and 7, GI of 2, EN of 35 and 40, EI of 4 and root galling of 4 and 9%, respectively, were tolerant. Sixty-one genotypes, including the standard susceptible cv. Ife Brown, with RF of 2.3-6.4, RI of 17.6-110.4, GN of 25-98, GI of 3-4, EN of 25-90, EI 3-4 and root galling of 15-50%, were susceptible. The cv. IAR 399-1, with a RF of 0.7, RI of 9.0, GN of 35, GI of 4, EN of 4, EI of 2 and galling of 15%, was considered hyper-susceptible.