Combnining Ability of Sweetpotato Yield in Endemic and Non-endemic Sweetpotato Weevil (Cylas formicarius) Environments in South West Nigeria

Introduction: Combining ability studies in sweetpotato marketable root yield were carried out using ten sweetpotato varieties and their F1 hybrids in Cylas formicarius endemic (Omu Aran) and free (Ibadan) environments during 2012 cropping season.

Study Design: The genetic material used for this experiment was from the germplasm collection of the Department of Agronomy, University of Ibadan, Nigeria. This material comprised of 10 varieties of sweetpotato: 5 orange fleshed, 3 white fleshed and 2 yellow fleshed.

Place and Duration of Study: The field trial was carried out in C. formicarius endemic (Omu Aran) and Non-endemic (Ibadan) environments both in South West Nigeria during the raining season of 2012.

Methods: Collected data were subjected to diallel analysis using Griffing (15) approach in method I (parents, crosses reciprocals together), Model I (fixed effects). Both general combining ability (GCA) and specific combining abilities (SCA) were computed using PBTools, version 1.4. for the 10 parents and their F1 hybrids with respect to C. formicarius.

Results and Discussion: The result obtained from this study showed that some parents were tolerant to C. formicarius, but level of tolerance varied probably due to differences in genetic background among the parental population or time of planting. Hybrids from the parents resisto, TIS 87/0087 displayed high performance in term of C. formicarius tolerance. These parents and their hybrids appeared to have gene pools for C. formicarius tolerance that can be manipulated and used to develop promising hybrids in South west, Nigeria.