Leaf to Fruit Ratio

leaf to fruit ratio, viticultural measurement which indicates the capacity of a vine to ripen grapes. The ratio of vine leaf area to fruit (grape) weight determines just how well a vine can mature grapes and how suitable they will be for winemaking. Although it is less understood and discussed, it can have an even more important effect on wine quality than yield, although it is the latter that is highly regulated in most European controlled appellations and frequently discussed by oenologists.

This ratio indicates the vine’s ability to manufacture compounds important for grape ripening. If most leaves are exposed to the sun, then the leaf area is proportional to the ability of the vine to make sugars by photosynthesis. Against this should be set the weight of grapes to be ripened. Some studies, however, show that photosynthetic rate can somewhat adjust to a low leaf to fruit ratio, and so the effect of over-severe leaf removal in the fruit zone, for instance, may not be as detrimental to ripening as anticipated.