Masters Degrees (Horticulture)

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Browsing Masters Degrees (Horticulture) by Author "Burger, Henning (Henning Jacobus),1978-"

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    Comparative analysis of four early white, seedless table grape cultivars in the Orange River area
    (Stellenbosch : Stellenbosch University, 2002-12) Burger, Henning (Henning Jacobus),1978-; Vivier, Melane A.; Orth, C.; Sadie, A.; Stellenbosch University. Faculty of AgriSciences. Dept. of Horticulture.
    ENGLISH ABSTRACT: The table grape industry is a major contributor to the South African economy, directly through foreign earnings from this predominantly export-based industry, as well as indirectly through the employment of thousands of people. It is a growing industry and consists of several production areas. The fastest growing table grape production area in South Africa is the Lower Orange River area, which produces some of the earliest grapes in the Southern Hemisphere. The biggest river in South Africa irrigates this area and it has an extreme climate characteristic of semi-desert areas. This area is considered to be optimal for the production of high quality, early, white seedless grapes. Previously, this area was predominantly planted to Sultanina vines for the purpose of raisin production. When seedless table grapes became a consumer preference, the producers very successfully converted their production practices to yield export quality seedless grapes from the established Sultanina vineyards. Extensive new plantings as well as re-plantings occurred in this area, also including newer cultivars from local and overseas breeding programmes. Being a viticultural and economical hot-spot, the Lower Orange River area is attracting much attention as a table grape production area and it also formed the backdrop to this study. The cultivar profile is changing in the area and it is projected that Sultana-, Regal-, Prime Seedless and Sugraone will be the four major early, white seedless cultivars in 2005. Based on this knowledge and prompted by a lack of information regarding production costs and general profitability of the new cultivars, this study was initiated in the form of a comparative analysis between the four mentioned cultivars spanning the early, middle and late regions of the Lower Orange River area. The approach used extracted information regarding cultural input costs (specifically labour as man-hours and the consequent costs) per manipulation performed in the vineyards. This approach is different from the more general method of obtaining input costs for a specific area based on combined mean values, often not distinguishing between cultivars. The specific aims of the study included a comparative analysis of input costs for production cultural practices per main manipulation action, as well as a comparative analysis taking into account productivity, value and extraordinary costs related to each of the four cultivars. To this end, 22 experimental plots were identified for use in the study. Collaboration of the production managers of each of the experimental plots were procured and information regarding production costs per manipulation and productivity of each cultivar and experimental plot were extracted from their own record keeping systems or from documents provided to the production managers. The value (price achieved) of the various cultivars for the 2001/2002 table grape season were put into perspective by using data from a survey which included information regarding payments for the various cultivars during the season in the Lower Orange River area. Information regarding fruit and vine royalties was obtained from the various plant breeders' rights holders of the various cultivars, where applicable. Primary descriptions of each experimental plot concerning general cultivation practices and information regarding the specific season were used to qualify results obtained from the various blocks. Several complicating factors impacted on the study and specifically the subsequent analyses of the results. Some of the factors were already identified as complicating factors in the planning stage of the study and were mostly linked to the recent introduction of two of the cultivars to the Orange River area. From the data gathered and the analyses performed it became clear that it would be difficult to discern significant differences (where significant is defined as PS0.10), but clear trends were observed and indications obtained. Based on the input cost analyses of this study it is proposed that mature Prime Seedless will have the highest labour input and cultural production cost of the four cultivars, followed by Sugraone. The labour input and the cost for the production cultural practices studied for young Prime Seedless vines were very high in comparison to the mature Sultana Seedless and Sugraone vines, especially for the canopy management and bunch manipulation actions. Prime Seedless was especially prone to the set of small and uneven berries, which lead to very high labour input requirements and subsequent cost for bunch manipulations. Sugraone is also known for the set of small and uneven berries in the Lower Orange River area, especially in difficult climatic seasons, also requiring high labour input for bunch manipulations. The initial indication is that mature Sultana- and Regal Seedless will require similar labour inputs for cultural production practices. The fact that Regal Seedless does not require expensive gibberellic acid (GA) applications, or girdling for thinning and berry enlargement purposes, is a tremendous advantage from a production cost point of view. Accordingly, initial indications are that Regal Seedless will have the lowest cultural production cost of the four cultivars. Regal Seedless was prone to the set of uneven berries during the year of study and accordingly it is suspected that this factor will ultimately determine the labour requirements and cultural production input cost, especially in difficult climatic seasons. The labour input and ultimately the cultural production cost for Sultana Seedless will be determined by the correct timing and concentration of the GA applications for thinning and berry sizing. Sultana Seedless and Sugraone produced high yields during the 2001/2002 table grape season in the Lower Orange River area. Yield information from the various experimental plots confirmed that there is little to choose between the two cultivars in terms of yield when cultivation conditions and practices are optimal. Large variation was observed in the yield results from the Regal- and Prime Seedless experimental plots. This is largely due to the recent introduction of the cultivars to the area and the consequent scarcity of blocks of these cultivars that are in full production. It was impossible to identify clear trends in terms of the future productivity of mature Regal- and Prime Seedless, but some indications of labour inputs could be extracted and qualified. Early maturing Prime Seedless and Sugraone performed very well in terms of price, especially in the harvest period prior to week 50. This advantage of high prices early in the season is, however, not always applicable to early cultivars in the later maturing regions of the Lower Orange River area. Later during the season, after week 50, when the supply of table grapes to the overseas markets has increased sharply, Sultana Seedless is usually the best performer in terms of price of the four cultivars. The ultimate price obtained by a cultivar is to a large extent determined by supply and demand, quality and acceptance of the specific cultivar. This study and its outcomes have a strong regional (Lower Orange River) and local (South Africa) impact and the specific results will undoubtedly be valuable to the producers, exporters and other role-players with vested interest in the cultivars studied or in table grape production per se. The methodology adopted in this study, however, is of broader interest and dearly shows the advantage of having detailed and qualified information regarding cultivation practices and bringing it in relation to the labour and consequent costs required per action. This should lead to more business intelligence and realistic planning on the producer side when decisions regarding the choice of a cultivar for a specific production area with a particular marketing scope have to be made. This study has also paved the way for similar studies, specifically with regard to the detailed description of the methodology that was established. Knowledge of the problems experienced in this study provides a useful reference for the planning and execution of similar studies.