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viticulture Viticulture (from the Latin word for ''vine'') or winegrowing (wine growing) is the cultivation and harvesting of grapes. It is a branch of the science of horticulture. While the native territory of ''Vitis vinifera'', the common grape vine, ra ...
, the yield is a measure of the amount of grapes or wine that is produced per unit surface of vineyard, and is therefore a type of
crop yield In agriculture, the yield is a measurement of the amount of a crop grown, or product such as wool, meat or milk produced, per unit area of land. The seed ratio is another way of calculating yields. Innovations, such as the use of fertilizer, the c ...
. Two different types of yield measures are commonly used, mass of grapes per vineyard surface, or volume of wine per vineyard surface. The yield is often seen as a quality factor, with lower yields associated with wines with more concentrated flavours, and the maximum allowed yield is therefore regulated for many wine appellations.


Units and conversions

In most of Europe, yield is measured in
hectoliters The litre (international spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3). ...
per hectare, i.e., by the volume of wine. In most of the New World, yield is measured in tonnes per hectare (or short tons per acre in the USA) – i.e. by mass of grapes produced per unit area. Due to differing
winemaking Winemaking or vinification is the production of wine, starting with the selection of the fruit, its fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over millennia. The science of wine and w ...
procedures for different styles of wine, and different properties of different grape varieties, the amount of wine produced from a unit mass of grapes varies. It is therefore not possible to make an exact conversion between these units. Representative figures for the amount of grapes needed for 100 L of wine are 160 kg for white wine, 130 kg for red wine, and 140 kg for a mixture of red and white wine. Thus: * for white wine, 100 hl/ha ≈ 16,000 kg/ha (16 t/ha) = 6.5 tons per acre. ** 1 ton per acre = 2470 kg/ha ≈ 15 hl/ha * for red wine, 100 hl/ha ≈ 13,000 kg/ha (13 t/ha) = 5.3 tons per acre. ** 1 ton per acre = 2470 kg/ha ≈ 19 hl/ha * for mixed wine, 100 hl/ha ≈ 14,000 kg/ha (14 t/ha) = 5.7 tons per acre. ** 1 ton per acre = 2470 kg/ha ≈ 17.5 hl/ha


Typical yields

Yields vary greatly between countries, regions and individual vineyards, and can be vintage-dependent. Somewhere around 50 hectoliters per hectare, or 3 tons per acre, is a typical representative figure for many countries and regions.


Yield as an indication of quality

While yield is generally seen as an important quality factor in wine production, views differ on the relative importance of low yields to other aspects of vineyard management. In general, there is consensus that if vines are cropped with a very high amount of grape clusters, a poor wine will result because of slow and insufficient ripening of the grapes, due to an unfavorable leaf to fruit ratio. This is a situation that would typically correspond to yields of, say, 200 hl/ha or more, depending on grape variety and many other factors. Beyond that, there are differing schools of thought. One school of thought, generally subscribed to in France, claims that great red wine is impossible to produce at yields exceeding 50 hl/ha. Another school of thought claims that a yield of 100 hl/ha is possible to combine with high quality, provided that careful
canopy management In viticulture, the canopy of a grapevine includes the parts of the vine visible aboveground - the trunk, cordon, stems, leaves, flowers, and fruit. The canopy plays a key role in light energy capture via photosynthesis, water use as regulated b ...
is used. In general, white wine is seen as less sensitive to high yields, and some grape varieties, such as
Pinot noir Pinot Noir () is a red-wine grape variety of the species ''Vitis vinifera''. The name may also refer to wines created predominantly from pinot noir grapes. The name is derived from the French language, French words for ''pine'' and ''black.' ...
, as particularly sensitive to overcropping. Many examples exist where a vintage-to-vintage variation of yields is in fact positively related with quality, since the low yields can be due to loss of grapes due to adverse conditions such as
hail Hail is a form of solid precipitation. It is distinct from ice pellets (American English "sleet"), though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailstone. Ice pellets generally fal ...
or
grey rot ''Botrytis cinerea'' is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" or ...
. For the
Bordeaux Bordeaux ( , ; Gascon oc, Bordèu ; eu, Bordele; it, Bordò; es, Burdeos) is a port city on the river Garonne in the Gironde department, Southwestern France. It is the capital of the Nouvelle-Aquitaine region, as well as the prefecture ...
vintages of the 1980s, it is generally recognized that the most abundant harvests also gave the best vintages.


Regulation of yields

In both France and Italy, the maximum allowed yields are regulated in
wine law Wine laws are legislation regulating various aspects of production and sales of wine. The purpose of wine laws includes combating wine fraud, by means of regulated protected designations of origin, labelling practices and classification of wine, ...
s, and vary between appellations. In France, the maximum yields are given in the regulations for each '' appellation d'origine contrôlée'' (AOC). The maximum allowed yield for given AOC in a given vintage is a combination of the base yield of the AOC, as modified by the ''plafond limité de classement'' (PLC), which is percentage set for each vintage. In most vintages, the PLC allows a production around 20 per cent above the base yield.


References

{{portal bar, Drink Viticulture Wine terminology