Evaluation of Some Improved Varieties of Cassava (Manihot esculenta) (Crantz) for Resistance to Cassava Bacterial Blight (CBB) in a Humid Forest Zone of Nigeria
Emiri, U. N.
Journal Title:Journal of Environmental Issues and Agriculture in Developing Countries
Ten improved varieties of cassava Manihot esculenta (Crantz) obtained from the International Institute of Tropical Agriculture (IITA) Ibadan and a local variety (Efuwa) which served as a local check were evaluated for resistance to Cassava Bacterial Blight (CBB) at the Rivers State Agricultural Development Programme (ADP) Research Farm, Degema, Rivers State, Nigeria. The varieties were laid out in a Randomized Complete Block Design and replicated three times. Field observation shows that seven varieties were resistant to CBB infection with proportional increase in tuber yield. Two categories of varieties were observed in the study. The first category which have higher resistance to CBB and good tuber yield thus having potential in reducing foliar diseases as well as increasing tuber yield, while the second category produces relatively higher biomass and good tuber yield. This group can therefore be cultivated for good foliage and tuber yield. The root number weight and above-ground biomass had a significant positive correlation with yield, while a negative correlation exists between incidence/severity and yield. Therefore, Varieties with high level of resistance are recommended for crop multiplication in humid rain forest zone of Nigeria.