ISHS Acta Horticulturae 194: International Symposium on Fruit & Vegetables for Processing
PROGRESS AND LIMITATIONS IN BREEDING OF THE SWEET POTATO (IPOMOEA BATATAS) IN SOUTH AFRICA |
| Author: | C.P. du Plooy |
| Abstract:
The sparse flowering habit of local sweet potato Ipomoea batatas (L.) Lam cultivars as well as low fertility and seedset were some of the first obstacles breeders in South Africa had to deal with. Several flower inducing techniques as well as inin vitro pollen germination and growth were investigated. Using I. setosa Ker. Gawl. as rootstock in combination with a short photoperiod (8 hours) enabled breeders to induce flowering in all local cultivars and breeding lines. Failure to set seed was associated with complete failure of pollen germination on the stigma. Four incompatibility groups within local sweet potato cultivars have been identified. Meiotic abnormalities to a certain extent may be responsible for low seedset, but are not the only limiting factors to seedset in the sweet potato. During 1980 a mass selection programme was initiated. Selections from the mass selection population as well as selections from various other sources are grown in polycross nurseries with naturally occurring insects as pollinators. Limiting the number of polycross entries ensures a dynamic breeding nursery which gradually improves each year. Comparative data as well as the breeding history of locally released cultivars are presented. Breeders in South Africa have succeeded in developing high yielding cultivars, adapted to local conditions. The development of cultivars with improved processing characteristics in combination with high yield is one of the main future goals. Several breeding lines have been developed and are being evaluated in co-operation with local processing industries. | |
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