Potato is a cool weather crop realising its highest yields and best quality in regions with mild temperatures, long days and ample rainfall during the growing season. Most of the commercial potato varieties available in the world today were developed in the traditional potato producing countries of the Northern Hemisphere where conditions are moderate and enough water for irrigation is available. These varieties are generally not adapted to the adverse conditions of short day lengths, high temperatures, low humidity and erratic rainfall, which is typical of the countries in Southern Africa. In addition, these varieties may be resistant or tolerant to the diseases and pests of the temperate climates, but they are generally not resistant to the pests and diseases of the warmer climates.
Potato production in South Africa was originally limited to specific areas where the climate suited the potato cultivars introduced from European countries. The major potato production areas were the highlands of the Mpumalanga and Free State Provinces, where potatoes were planted during spring and grown without supplementary irrigation. Although the rest of the country had a limited production in scattered areas, the supply of fresh potatoes was completely seasonal. Potato production in South Africa increased dramatically after the release of the first locally developed varieties, which were adapted to short day conditions and resistant/tolerant to the prevailing pests and diseases. This increase in production was not only due to the development of new production regions in the Limpopo, Free State, Western Cape and Kwazulu-Natal Provinces, but also to the utilisation of different planting dates (different seasons) in the existing production regions. The expansion of potato production to regions with widely different climates and the utilisation of different seasons in these regions, ultimately led to the current need for varieties with improved yield stability, heat tolerance, drought tolerance, and pest ? and disease resistance.
Approximately 20% of the total potato crop in South Africa is annually utilised for processing. Although the South African potato processing industry grew by more than 100% between 1990 and 2000, this growth has slowed down during recent years due to a shortage of high quality potatoes.
This shortage may be attributed to the international unavailability of heat tolerant processing varieties and the current use in South Africa of poorly adapted processing varieties from Europe and North America.
The increased importance of various soil-borne and foliar diseases, the need to reduce the use of pesticides, lack of water for agriculture and an increased demand for improved tuber quality, currently directs the future outputs of the ARC-VOP potato breeding programme.
In the potato breeding program, local and foreign potato varieties, advanced breeding lines and tuber-bearing
Solanum species with specific desirable characteristics are used. Controlled pollinations are made and the progeny are evaluated for various tuber characteristics, as well as their tolerance to heat stress, water stress, common scab and virus diseases. From the results of these progeny evaluations, superior parent combinations and superior parents are identified. The selected parents and parental combinations are then utilised for the production of botanical potato seed for the variety development programme. Evaluation is done in three phases. The first phase of clone evaluation consists of three consecutive plantings for evaluation and seed multiplication. During the second phase of clone evaluation more emphasis is placed on the yield potential, disease tolerance and quality characteristics in replicated field trials. During the third phase of clone evaluation, the adaptability of clones selected from the second phase evaluations are tested for three years in multi-location field trials representative of the 14 potato production areas in South Africa. Clones selected from this phase of evaluation are annually recommended for commercial evaluation by South African producers. Concurrent with the field trials, the clones go through a virus elimination program to ensure that virus-free plant material of selected clones would be available for the eventual commercial evaluation of the most promising clones.
CULTIVARS AND PRODUCTS
Above: FRODO – a high yielding, white fleshed, dual purpose (table and processing) variety, moderately tolerant to early blight, late blight and common scab.
Above: FABIEN – a high yielding, smooth skinned, white fleshed, dual purpose variety moderately tolerant to drought, early blight and late blight.