Masters Degrees (Viticulture and Oenology)

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Browsing Masters Degrees (Viticulture and Oenology) by Author "Barker, Wilma (Wilma Henriette)"

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    Die invloed van mangaan op vrugrypwording by Vitis Vinifera L. cv. Pinotage
    (Stellenbosch : Stellenbosch University, 1964-12) Barker, Wilma (Wilma Henriette); De Bruyn, J. A.; Stellenbosch University. Faculty of AgriSciences. Dept. of Viticulture and Oenology and Institute for Wine Biotechnology .
    ENGLISH ABSTRACT: The influence of manganese sulphate sprays on the yield and ripening of fruit of manganese-deficient Vitis vinifera L. (cv. Pinotage) plants was investigated. Ripening was determined in terms of changes in concentration of the indivi= dual and total sugars and organic acids. Increasing concentrations of manganese sulphate resulted in significant increases in the manganese content of the leaves. The higher levels of manganese were associated with an increase in yield. Ripening, however, was retarded, in that the percentage sugar of the fruit was decreased and titrable acid content increased. The principal sugars present in the fruit were sucrose, glucose, fructose and xylose. Malic and tartaric acids were the main organic acid constituents. Glucose and fructose increased sharply, and sucrose and xylose slightly during ripening of the fruit, whereas malic and tartaric acid de= creased. Glucose, fructose, tartaric and malic acid tended to increase with increasing manganese content. Sucrose and xylose were not appreciably affected. An application of 1% manganese sulphate can be recommend- · ed for manganese deficient vineyards, as it results in an increased yield, in addition to delaying ripening until a more favourable time for handling. Furthermore, the lowered sugar content of the fruit may be advantageous for the pro= duction of dry wines from Pinotage grapes .