Nitrogen and to a lesser extent potassium have a direct effect on increasing wine grape berry size. In this trial there was a correlation with grape bunch weight in two out of three years of this trials.
Increasing wine grape berry size
While smaller grapes may produce a more intensely flavored, quality wine, the grower needs to balance this with the need for a high yield from well-sized berries on his vines. The producer must therefore seek an acceptable compromise between high wine grape yield and high quality that meets his aspirations and those of his chosen winery.
A balanced fertiliser programme is also important to increase wine grape berry size.
Crop Nutrition and Wine Grape Berry Size
Nitrogen
Phosphorus
Where phosphorus is naturally low in soils, applied fertiliser phosphate increases wine grape berry set and crop yield.
Other Crop Management Practices Influencing Wine Grape Berry Size
- Minimal pruning or growth manipulation will result in smaller, but better quality wine grapes. However, it may also delay maturity and compromise other quality characteristics. Plant growth regulation can improve wine grape fruit set, increasing yields in vines, creating bunches with smaller berries.
- Inducing moisture stress between fruit set and veraison can reduce berry size by 20-30%. Increasing water availability at maturity will boost sugars by increasing grape pulp, but at the same time this reduces the amount of skin and phenolic compounds in the must.
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