BREEDING AND EVALUATION

Current Projects: Strawberries

Objectives:

Breeding of new, locally adapted cultivars for the fresh market and processing industry through crossing of suitable parents, followed by selection of the most promising seedlings.

Recent achievements:

During the 2000 growing season 56 different cross combinations were utilised in expanding the available range of genetic variation from which new, locally adapted strawberry cultivars for the fresh market and processing industry can be developed. Sufficient quantities of seed were produced in this manner and in general good germination rates were observed. Although Colletotrichum crown rot caused great losses, the goal of 5 000 seedlings had still been reached. A trial, conducted to determine the influence of temperature during germination, as well as genetic variation on the germination rate of 15 different strawberry cross combinations, showed that it will not be more beneficial to germinate strawberry seed at lower temperatures in a climatic controlled chamber. Genetic variation did however have a pronounced effect as could be seen from the 6 - 42 % variation in average germination rate. A total of ± 5 000 seedlings, developed from 56 cross combinations, were subjected to Phase I evaluation. One hundred and forty seven single plant selections were identified, using fruit quality (fruit size, firmness, taste and appearance) as selection criteria. Fifty one different cross combinations of parents and the development of 5 000 seedlings are planned for the 2001 season. Promising 97-selections were selected as female parents, whereas the French cultivar, Marié de Bois, two local selections and three imported selections will be utilised as pollen parents.

Objectives:

The evaluation of locally bred selections and imported cultivars for characteristics as required by the fresh market and processing industry.

Recent achievements:

During the 2000 growing season, locally developed selections were evaluated for characteristics as required by the fresh market and processing industry. A total of 183 selections were subjected to Phase II evaluation. Fruit size, firmness, taste and appearance were considered the most important selection criteria. In addition, production data were also utilised to identify the 29 most promising selections. Many of these did however produce very few runners and thus only 10 selections could be promoted to the next phase. The Phase III evaluation trial was conducted as a statistic trial, laid out according to a randomised block design (n = 5) and included 35 entries (9 cultivars, 10 selections that were made during the years 1980-1995 and 16 new selections). Average fruit mass and yield per hectare, as well as fruit quality, served as key elements in the calculation of two selection indexes (fresh market and processing respectively) per entry. Based on these indexes, 97-51, 97-148 and 97-151 were identified as the most promising dual purpose selections, followed closely by S1-94-2-1, S1-94-17-4, 97-191 and the cultivars, Veltheimia and Chandler. In an attempt to achieve even more objectivity in the evaluation of fruit quality, a standard fruit analysis was performed by Hortec. Although the colour assessments did not seem very informative, an analysis of fruit firmness, sugar content and acidity would definitely provide more objective data. Statistic proof that especially fruit mass and yield per hectare are greatly influenced by genotype x environment interaction, was found when three years’ Phase III data on 19 cultivars and selections were pooled. During June 2000, runner plantlets of the promising, locally developed cultivar, Veltheimia, were established in a mother block at the Tandfontein nursery and will be planted in a commercial propagation block this coming year. The French strawberry cultivar, Darsanga, was released from quarantine in June 2000 and will hopefully soon be followed by a further three cultivars, Siabelle (French), Andana and Carisma (Spanish).

Talks

DU TOIT, J.M., 2001. Breeding and evaluation of new strawberry cultivars and selections adapted to local conditions in the Western Cape. Presentation. Cape Strawberry Growers’ Association Annual General Meeting, 8 May, ARC Infruitec-Nietvoorbij, Infruitec campus, Stellenbosch (Afrikaans).

DU TOIT, J.M., 2001. Breeding objectives of the stone fruit rootstock project. Presentation. Operational Committee for Product Development: Stone fruit, 23 May 2001, ARC Infruitec-Nietvoorbij, Infruitec campus, Stellenbosch (Afrikaans).

DU TOIT, J.M., 2001. Report back on the results of the stone fruit rootstock project for the 2000/01 season. Presentation. Operational Committee for Product Development: Stone fruit, 2 October 2001, ARC Infruitec-Nietvoorbij, Infruitec campus, Stellenbosch (Afrikaans).

Overseas visitor: Director-General of the Société Nationale De La Protection Des Végétaux in Tunisia, Mr. Sahbi Tanoubi. Information on the strawberry industry in South Africa, 1 February 2002. ARC Infruitec-Nietvoorbij, Infruitec campus, Stellenbosch.

Top of Page
Breeding and Evaluation Division