Evaluation of Sweet Potato (Ipomea Batatas, L.) Cultivars and Advanced Breeding Lines For Resistance to Two Root-Knot .Nematode Species (M. Incognita & M. Javanica)

Abstract

Several sweet potato cultivars and advanced breeding lines were screened in both the greenhouse and a heavily nematode infested field for resistance to root-knot nematode species (Meloidogyne incognita and Meloidogvne javanica). Two greenhouse methods, "The Bed Method" and "The Improved Method" were used for indoor investigations. A heavily nematode infested field was used for outdoor investigations. The infestation in the field had been built up over a period of three years. Plants in all investigations were evaluated on a scale of 1-5 based on the percentage number of roots infested using both gall and egg mass indices. Several breeding lines, namely, FH-7-72, TI-1&92, L3-186, TI-15S-76, TI-152-76 and TI-I84-76 were resistant to M. incognita; however only FH-7-72, TI-1892 and L3-186 were comparable to ’Jewel’ in their resistance. ’Carver’ and ’Rojo Blanco’, two newly released cultivars from Tuskegee Institute were intermediate in resistance and susceptibility respectively when inoculated with M. incognita. When plants were screened for resistance to M. .jayanica, TI-1892, ’Carver’, FH-7-72, TI-1895, TI-164-76, TI-152-76,