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Abstract
Orange-fleshed sweet potato, high in provitamin A carotenoids, were introduced to Africa from the United States, but there was a shortage of varieties with desirable traits for South African conditions, namely, stable yield, good total carotenoid content, and good taste. Desirable characteristics were combined annually through the polycross method using parents selected for specific traits, followed by clonal selection phases and multi-location advanced yield trials. Genotype by environment analysis of advanced lines indicated two locally bred lines, 1998-21-1 (released as “Impilo”) and 1999-1-7, as the best. Other useful clones were 1999-6-1 (released as “Khano”) and U.S. variety “Resisto.” These were recommended for use in food-based approaches to address vitamin A deficiency. In addition, three new promising lines were identified, viz., 2001-5-2, 2000-6-1, and 2000-10-7, which needed to be evaluated in multi-location trials to determine their adaptability. Future breeding efforts could concentrate on higher levels of total carotenoids and stable high yields, and in addition, on tolerance to drought and Alternaria stem blight.
The authors acknowledge the Department of Agriculture and communities in the various provinces for their role in execution of the advanced yield trials; Ms. Marie Smith of the ARC-Biometry Unit for data analysis; Mr. Vusi Nkosi, and Mr. Jan Viljoen and team for the multiplication of the material at the ARC-VOPI; the International Potato Center (CIP) for their partnership; the ARC, Sustainable Rural Livelihood Division of the ARC and HarvestPlus for funding the project; Mr. Robert Laurie for total carotenoid extraction and measurement; Dr. Patrick Adebola of the ARC-VOPI for valuable advice on the manuscript; and Dr Paul Shanahan, University of KwaZulu-Natal for providing variety “A15.”