Abstract
This study assessed the genetic diversity and differentiation in sweetpotato accessions in Ghana to guide selection for genetic improvement on beta-carotene, dry matter and sugar contents to promote increased utilization. One hundred and fifteen sweetpotato accessions from four different sources, which were the International Potato Centre (CIP) collection, local collection from farmers’ field, local improved varieties, and local and exotic collections from the National Agricultural Research Programmes were studied using 40 agro-morphological and physico-chemical traits, and 25 SSR markers. Variability was obtained for 13 agro-morphological traits and all the physico-chemical traits. Significant genetic diversity indicates existence of a high degree of agro-morphological and physicochemical variation. Within Group variation (97%) accounted for most of the diversity indicating a broad genetic base. The divergence indicates that breeders can form different populations with significant levels of genetic variation to exploit heterosis and improvement of populations. A strong negative relationship was found for sugar content and dry matter content and indicates a possible development of non-sweet high dry matter sweetpotato varieties. However, developing non-sweet, high dry matter and high beta-carotene sweetpotato varieties could be challenging due to the strong negative association between dry matter content and beta-carotene content, and the positive association existing between beta-carotene and sugar content. This study has in addition confirmed the breeding potential of sweetpotato accessions in Ghana and the probability of providing useful genetic variation for the development of farmer preferred cultivars. Key words: Analysis of Molecular Variance (AMOVA), diversity, end-user, simple sequence repeats (SSR) markers, Sweetpotato, traits.
Highlights
The Analysis of Molecular Variance (AMOVA) and Analysis of Variance (ANOVA) results indicated significant differences within and between the different sweetpotato groups studied. These results demonstrate significant genetic diversity and indicates that meaningful selection and improvement of these traits is possible (Mohammed et al, 2012; Nwangburuka and Denton, 2012)
This study provides estimate on the level of genetic variation among sweetpotato accessions in Ghana
Significant genetic diversity was found between the accessions for dry matter, beta-carotene and sugar content
Summary
The level of utilization in Ghana is very low and it is not well integrated into Ghanaian diets (Adu-Kwarteng et al, 2002) This is because consumers in Ghana prefer sweetpotato with dry mealy flesh, non-sweet, and high nutritive value (Sam and Dapaah, 2009; Baafi et al, 2015), but locally available varieties are sweet that limits consumption as a staple food (Missah and Kissiedu, 1994). The recently introduced orange-flesh genotypes, identified as a cheapER source of Vitamin A, are low in dry matter content. These factors have led to the low adoption of the 13 varieties released to date. There is, the need to incorporate nonsweetness, high dry matter, and/or high beta-carotene contents into the existing genetic background of high yielding and early maturing cultivars which are resistant to biotic and abiotic stresses
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