- C D Eardley & M W Mansell
- Biosystematics Division, Plant Protection Research Institute, Private Bag X134, Pretoria 0001
- 1994
The genetic improvement of the litchi worldwide has been carried out by means of selection of open pollinated seedling trees of known cultivars. Only a few cultivars of importance, e.g. Salathiel, Kwai May Pink, Wai Chee, Sah Keng, Chacapat, and Kaimana have been selected during the past 60 years. In South Africa only two cultivars, Mauritius (Tai So) and Madras (McLean Red), have been planted since the start of the industry some 100 years ago. At present there is a demand for high quality early and late season cultivars, mainly because of competition from Madagascar and to lengthen the harvesting season. A purposeful breeding programme has been initiated at the ITSC, where honeybees in shadecloth cages will be used to self- and cross pollinate promising cultivars. No success has been obtained until now with controlled hand pollination. Another problem in the breeding programme is the long juvenile phase of a litchi seedling tree. Manipulation techniques, namely using growth regulators, girdling (ringbarking) and pruning, will be evaluated on more than 2 000 seedling trees, which were established during the 1990/91 season.
Although the breeding programme is a long term project, the ITSC hopes to establish at least 1 000 seedling trees per year, evaluate the most promising ones in a Phase II evaluation programme and be able to release well adapted, high quality early and late litchi cultivars to the South African litchi industry.
Summary:
- The genetic improvement of litchi worldwide has mainly been through selection of open-pollinated seedling trees of known cultivars, with few notable new cultivars developed in the past 60 years.
- In South Africa, only two cultivars, Mauritius Tai So and Madras McLean’s Red, have been planted since the litchi industry began about 100 years ago.
- There is a growing demand for high-quality early and late-season litchi cultivars to extend the harvesting season and compete in international markets, especially against Madagascar.
- A purposeful breeding program was initiated at the Institute for Tropical and Subtropical Crops (ITSC) in Nelspruit, South Africa, focusing on controlled self- and cross-pollination using honeybees housed in shadecloth cages.
- Controlled hand pollination has not yet been successful in this breeding program.
- The long juvenile phase of litchi seedlings is a significant challenge; techniques such as growth regulators, girdling, ringbarking, and pruning are being tested on over 2,000 seedling trees to shorten this phase.
- The breeding program consists of three parts: open pollination, self-pollination, and cross-pollination, aiming to produce seedlings with unique, desirable traits.
- Cross-pollination allows the combination of advantageous traits such as early or late ripening, good fruit color, size, flavor, and resistance to pests and diseases.
- Over 1,000 seedlings from self- and open-pollinated crosses have been planted in nurseries, with promising selections being grafted and evaluated in phased trials (Phase I, II, and III) for climatic adaptation and semi-commercial testing.
- The breeding program is long-term, with plans to establish at least 1,000 seedlings annually and release well-adapted, high-quality cultivars for the South African litchi industry.
- Until improved cultivars are developed and released, the industry will rely on existing local and imported cultivars.