Die invloed van mangaan op vrugrypwording by Vitis Vinifera L. cv. Pinotage

[摘要] ENGLISH ABSTRACT:The influence of manganese sulphate sprays on the yieldand ripening of fruit of manganese-deficient Vitis vinifera L.(cv. Pinotage) plants was investigated. Ripening was determinedin terms of changes in concentration of the indivi=dual and total sugars and organic acids.Increasing concentrations of manganese sulphate resultedin significant increases in the manganese content of theleaves. The higher levels of manganese were associated withan increase in yield. Ripening, however, was retarded, inthat the percentage sugar of the fruit was decreased andtitrable acid content increased.The principal sugars present in the fruit were sucrose,glucose, fructose and xylose. Malic and tartaric acids werethe main organic acid constituents. Glucose and fructoseincreased sharply, and sucrose and xylose slightly duringripening of the fruit, whereas malic and tartaric acid de=creased. Glucose, fructose, tartaric and malic acid tendedto 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 anincreased yield, in addition to delaying ripening until amore favourable time for handling. Furthermore, the loweredsugar content of the fruit may be advantageous for the pro=duction of dry wines from Pinotage grapes .

[发布机构] Stellenbosch University