Vol 1 Issue 1 July 2020-December 2020
Mpapale S. John, Ajanga Sammy, Muyekho N. Francis
Abstract: Sweet potato (Ipomoea batatas, L) is the third most important food crop in Kenya after maize and Irish potato. Research efforts have been devoted to select, breed, and disseminate improved sweet potato varieties (ISVs) that enhance the productivity and quality to alleviate poverty, nutritional food insecurity and poverty among the rural households. Among the barriers to the introduction of ISVs are the diseases of biological origin. Alternaria blight disease has been ranked as the most important fungal disease of sweet potato in East Africa. Several genotypes have been developed by the Kenya Agriculture and Livestock Research Organization (KALRO) that are high yielding, early maturing together with other enhanced nutritional characteristics. However, their performance in the existence of various diseases that prevail in different Agro-ecological zones of Kenya has not been established. This study evaluated ISVs from KALRO for resistance/tolerance to Alternaria blightdisease in different AEZs of western Kenya. Nine sweet potato varieties were planted at Kakamega, Kakamega county-high rainfall site and Alupe, Busia county – low rainfall site. A Randomized Complete Block Design (RCBD) with three replications was used. Inoculum of Alternaria solani was cultured from infected SPK 004 in KARLO Kakamega laboratory, and applied to all the treatments 6 weeks after planting. All the ISVs were assessed for Alternaria disease incidence at different stages using standard scale of 1-5. Yield data was taken at a physiological maturity by harvesting the crops in each plot and weighed. The data was analysed using combined ANOVA and simple correlation using SAS software Version 8. The study revealed that the rate of progression for Alternaria disease against improved sweet potato varieties in Kakamega and Alupe was low compared to the unimproved varieties. There was a significant negative effect of Alternaria disease on the yield of both the improved and unimproved sweet potato varieties. Alternaria disease severity was significantly more vicious at KALRO Alupe than in KALRO Kakamega. None of the varieties was susceptible or resistant to the disease. All varieties were moderately resistant except Kabode and Namunyekera which were moderately susceptible. At Kakamega root yield varied significantly between the varieties where Kenspot1 recorded the highest yield (18.2 t/ha) while SPK013 had the lowest yield (10.1 t/ha). At Alupe yield did not vary significantly between the varieties but Kenspot5 had the highest yield (18.3 t/ha). The study concludes that most improved sweet potato varieties were tolerant to Alternaria blight disease in different AEZs of western Kenya. The study recommends that there is need for more baseline surveys to be conducted on adoption and performance of the new disseminated varieties in all high altitude areas of the country, use healthy, clean, fungal free planting materials and proper field sanitation.
Keywords: Agro-ecological zones, Alternaria disease, Resistance, Sweet potato.
Title: Resistance levels of Improved Sweet Potato Varieties to Alternaria Disease in different Agro-ecological Zones of Western Kenya
Author: Mpapale S. John, Ajanga Sammy, Muyekho N. Francis
International Journal of Recent Research in Thesis and Dissertation (IJRRTD)
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