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Laurie S.M.,Agricultural Research Council ARC Roodeplaat Vegetable and Ornamental Plant Institute | Booyse M.,Agricultural Research Council Biometry Unit

Sweetpotato is a good source of energy, easy-to-grow and hardy and thus useful in contributing to food security. The current study aimed at identification of the best sweetpotato varieties for multiple desirable traits such as good yield, adaptability (including vine vigor) and tastiness (high dry mass content; taste). Ten South African sweetpotato varieties were evaluated during the period 2002/3–2007/8 at six locations each over two seasons. The sites regression model (SREG) of the genotype plus genotype by environment interaction (GGE) biplot analysis was performed with GenStat to determine stability and adaptability of the varieties. Subsequently, multiple trait selection was performed by using the ranking from Elston index selection. To enable inclusion of varietal stability in multiple trait selection, a stability value was calculated. High yielding varieties included Blesbok, Monate, Ndou and Letlhabula, of which Monate and Letlhabula had stable performance. The advantage, particularly for resource-poor farmers, of a specifically adapted, responsive variety such as Ndou, is the ability to respond to changes in the environment. Based on multiple trait selection varieties Ndou and Monate were recommended for production. The results present an innovative use of Elston index selection, including a stability value, in combination with GGE SREG for recommending varieties with multiple desirable traits. The recommended varieties are of significance for future use to improve food security. © 2015, Springer Science+Business Media Dordrecht. Source

Laurie S.M.,Agricultural Research Council ARC Roodeplaat Vegetable and Ornamental Plant Institute | Booyse M.,ARC Biometry Unit | Labuschagne M.T.,University of the Free State | Greyling M.M.,Agricultural Research Council ARC Roodeplaat Vegetable and Ornamental Plant Institute
Crop Science

Vitamin A deficiency is a serious health problem in South Africa, as in several parts of the world. One strategy to combat micronutrient deficiency is through biofortification, particularly through orange-fleshed sweetpotato [Ipomoea batatas (L.) Lam]. Previously, a shortage existed in South Africa of orange-fleshed genotypes with a combination of high dry mass, good yield, and good taste. Local cream-fleshed parents and orange-fleshed US introductions were used in the local polycross program. This study aimed at testing the agronomic performance, stability, and genetic diversity of newly developed orange-fleshed genotypes. Twelve entries, nine with orange flesh color, were evaluated at four sites for two seasons in multienvironment trials and the data was subjected to ANOVA and genotype plus genotype-by-environment interaction (GGE) biplot analysis. Simple-sequence repeat (SSR) analysis of the 12 entries was done followed by hierarchical clustering. Two of the orange-fleshed cultivars were recommended for production and plant breeders’ rights were registered for these. Cultivar Impilo produced stable, high root yield similar to the commercial control cultivar Beauregard; while the elite breeding line Purple Sunset (2001_5_2) had high yield and specific adaptability. Both displayed average dry mass and acceptable taste. The genetic analysis indicated relatedness of most new genotypes with the cream-fleshed parents used in the polycross program. The improved cultivars offer considerable yield advantage above US introductions previously recommended for combating vitamin A deficiency. © Crop Science Society of America. Source

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