Comparative analysis of four early white, seedless table grape cultivars in the Orange River area

[摘要] ENGLISH ABSTRACT:The table grape industry is a major contributor to the South African economy, directlythrough foreign earnings from this predominantly export-based industry, as well asindirectly through the employment of thousands of people. It is a growing industry andconsists of several production areas. The fastest growing table grape production area inSouth Africa is the Lower Orange River area, which produces some of the earliest grapesin the Southern Hemisphere. The biggest river in South Africa irrigates this area and it hasan extreme climate characteristic of semi-desert areas. This area is considered to beoptimal for the production of high quality, early, white seedless grapes. Previously, thisarea was predominantly planted to Sultanina vines for the purpose of raisin production.When seedless table grapes became a consumer preference, the producers verysuccessfully converted their production practices to yield export quality seedless grapesfrom the established Sultanina vineyards. Extensive new plantings as well as re-plantingsoccurred in this area, also including newer cultivars from local and overseas breedingprogrammes. Being a viticultural and economical hot-spot, the Lower Orange River areais attracting much attention as a table grape production area and it also formed thebackdrop 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 in2005. Based on this knowledge and prompted by a lack of information regardingproduction costs and general profitability of the new cultivars, this study was initiated in theform 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 extractedinformation regarding cultural input costs (specifically labour as man-hours and theconsequent costs) per manipulation performed in the vineyards. This approach is differentfrom the more general method of obtaining input costs for a specific area based oncombined mean values, often not distinguishing between cultivars. The specific aims ofthe study included a comparative analysis of input costs for production cultural practicesper main manipulation action, as well as a comparative analysis taking into accountproductivity, value and extraordinary costs related to each of the four cultivars. To thisend, 22 experimental plots were identified for use in the study. Collaboration of theproduction managers of each of the experimental plots were procured and informationregarding production costs per manipulation and productivity of each cultivar andexperimental plot were extracted from their own record keeping systems or fromdocuments provided to the production managers. The value (price achieved) of thevarious cultivars for the 2001/2002 table grape season were put into perspective by usingdata from a survey which included information regarding payments for the various cultivarsduring the season in the Lower Orange River area. Information regarding fruit and vineroyalties was obtained from the various plant breeders' rights holders of the variouscultivars, where applicable. Primary descriptions of each experimental plot concerninggeneral cultivation practices and information regarding the specific season were used toqualify results obtained from the various blocks.Several complicating factors impacted on the study and specifically the subsequentanalyses of the results. Some of the factors were already identified as complicatingfactors in the planning stage of the study and were mostly linked to the recent introductionof two of the cultivars to the Orange River area. From the data gathered and the analysesperformed it became clear that it would be difficult to discern significant differences (wheresignificant 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 Seedlesswill have the highest labour input and cultural production cost of the four cultivars, followedby Sugraone. The labour input and the cost for the production cultural practices studiedfor young Prime Seedless vines were very high in comparison to the mature SultanaSeedless and Sugraone vines, especially for the canopy management and bunchmanipulation actions. Prime Seedless was especially prone to the set of small and unevenberries, which lead to very high labour input requirements and subsequent cost for bunchmanipulations. Sugraone is also known for the set of small and uneven berries in theLower Orange River area, especially in difficult climatic seasons, also requiring high labourinput for bunch manipulations.The initial indication is that mature Sultana- and Regal Seedless will require similarlabour inputs for cultural production practices. The fact that Regal Seedless does notrequire expensive gibberellic acid (GA) applications, or girdling for thinning and berryenlargement purposes, is a tremendous advantage from a production cost point of view.Accordingly, initial indications are that Regal Seedless will have the lowest culturalproduction cost of the four cultivars. Regal Seedless was prone to the set of unevenberries during the year of study and accordingly it is suspected that this factor willultimately determine the labour requirements and cultural production input cost, especiallyin difficult climatic seasons. The labour input and ultimately the cultural production cost forSultana Seedless will be determined by the correct timing and concentration of the GAapplications for thinning and berry sizing.Sultana Seedless and Sugraone produced high yields during the 2001/2002 tablegrape season in the Lower Orange River area. Yield information from the variousexperimental plots confirmed that there is little to choose between the two cultivars interms of yield when cultivation conditions and practices are optimal. Large variation wasobserved in the yield results from the Regal- and Prime Seedless experimental plots. Thisis largely due to the recent introduction of the cultivars to the area and the consequentscarcity of blocks of these cultivars that are in full production. It was impossible to identifyclear trends in terms of the future productivity of mature Regal- and Prime Seedless, butsome 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 inthe season is, however, not always applicable to early cultivars in the later maturingregions of the Lower Orange River area. Later during the season, after week 50, when thesupply of table grapes to the overseas markets has increased sharply, Sultana Seedless isusually the best performer in terms of price of the four cultivars. The ultimate priceobtained by a cultivar is to a large extent determined by supply and demand, quality andacceptance 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 theproducers, exporters and other role-players with vested interest in the cultivars studied orin table grape production per se. The methodology adopted in this study, however, is ofbroader interest and dearly shows the advantage of having detailed and qualifiedinformation regarding cultivation practices and bringing it in relation to the labour andconsequent costs required per action. This should lead to more business intelligence andrealistic planning on the producer side when decisions regarding the choice of a cultivar fora specific production area with a particular marketing scope have to be made. This studyhas also paved the way for similar studies, specifically with regard to the detaileddescription of the methodology that was established. Knowledge of the problemsexperienced in this study provides a useful reference for the planning and execution ofsimilar studies.

[发布机构] Stellenbosch University