Root-yield performance of pre-release sweet potato genotypes in Kenya

Objective: The focus of this study was to evaluate the yield and stability of superior sweet potato cultivars for release in Kenya. This is the first attempt to document experimental results that have led to the first and so far only sweet potato variety release in Kenya. Methodology: Ten national performance trials laid out as randomized complete block designs were performed on 14 sweet potato (Ipomoea batatas (L.) Lam.) genotypes in two geographical locations of Kenya. The trials were conducted to select local and introduced genotypes that were high yielding, stable, and tasty. Four experiments involving all the 14 genotypes were carried out in Nairobi while six experiments involving nine of the genotypes were carried out at three sites in Western Kenya. The stability of root yield and palatability test ranking were determined using appropriate statistical tools. Results: Significant (P = 0.05) differences in root yield between genotypes were observed for both locations. Mean root yield was higher in Nairobi (16,760 kg ha-1) than in Western Kenya (15,150 kg ha-1). The proportion of marketable roots was higher in Nairobi than in Western Kenya. Dry matter content was also higher in Nairobi (29.63%) than in Western Kenya (26.58%). Genotype x environment (G×E) interactions were significant (P = 0.05) in both locations. Conclusion and applications: Recommendations on the suitable varieties for official release are given. KEMB 10 and Mugande were the best performers in both environments. These two varieties contribute to enhancing food security among small scale household farmers in rural Kenya. Since its release in 2000, SPK 004 has contributed to enhancing the availability of the beta carotene micronutrient.