Authors : Idorenyin A. Udo , Peter O. Ogbaji and Donald A. Ukeh
Abstract: Twenty-one cassava cultivars from International Institute of Tropical Agriculture�s (IITA) germplasm collections were evaluated for their responses to natural and artificial infection by Meliodogyne incognita race 1 in Calabar humid forest zone, Nigeria. In the screenhouse trial, individual plants were inoculated with 5,000 eggs of the nematode species. Uninoculated plants served as the control. For both experiments, infected plants were scored for galling and egg mass production on a 0-5 rating scale. Galls were observed only in feeder root and none on tubers. The cassava cultivars significantly (p 0.05) differed in their severity of galling and egg mass production. Five cultivars (96/1642, 99/2123, 91/02324, TMS 30572 and 92B/0061) had no galls and were rated immune with a Gall Index (GI) = 0. Four cultivars (97/3200, 95/0166, 94/0039 and 96/1089A) were rated resistant with GI 2. The nematode infection decreased stalk height, top fresh and dry weights and fresh root weight in all the cassava cultivars. Fresh storage root weight reduction ranges from 1.06% (95/00379) to 34.04% (94/0026). Five cultivars (91/02342, 4(2)1425, 95/00379, 82/00058 and 97/3200) were rated tolerant with severe root gallings but insignificant storage root weight decrease. These results indicate that promising source materials are available for improving cassava cultivars against root-knot nematodes.
Idorenyin A. Udo , Peter O. Ogbaji and Donald A. Ukeh , 2008. The Response of Some Cassava (Manihot esculenta Crantz). Cultivars to Infection by Meloidogyne incognita Race 1 in Calabar, Nigeria . Agricultural Journal, 3: 25-30.