Field performance and reaction to weevils of improved and local sweetpotato genotypes in Cameroon

Pages 290-297

J.M. Ngeve

ABSTRACT

Three sites differing in soil type, temperature, vegetation and weevil pressure, were used to evaluate the field performance of 18 sweet potato clones and two local cultivars and their reaction to weevils (Cylas spp.), in Cameroon. The wet season crop produced higher yields than the dry season crop. Clones 048 and 1112 produced the highest storage root yields (about 17 t/ha) across sites during the rainy season but only 12 t/ha in the dry season. Marketable yields were also higher (10 t/ha) in the wet season crop than in the dry season crop (6 t/ha). The highest yields were obtained in Nyombe in both wet and dry seasons; yields were halved in each of the other sites. Stability methods differed in identifying stable clones, and differed in ranking clones depending on the trait measured. However, both Eberhart-Russell and Shukla stability methods rated clones 048, Tib 1, 1602, 1639, 002 and Njombe as stable for root yields. Clones suffered more weevil damage in the dry season than in the wet season. Root yields and related characters where highly correlated with weevil damage. There relationship between weevil tolerance and cultivar adaptability was not consistent. This study shows that the main sweet potato crop should be grown during the first cropping season when there is abundant moisture for slip sprouting and establishment and when there is little soil cracking to facilitate weevil infestation. The study suggests that since root yields are adversely affected by weevil damage, weevil control measures should be seriously considered in commercial sweet potato production. Lastly, it suggests that since fewer clones were found to carry high levels of tolerance to weevils, further research is necessary in breeding for resistance to weevils.

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