Inviticulture, theyield is a measure of the amount ofgrapes orwine that is produced per unit surface ofvineyard, and is therefore a type ofcrop yield. Two different types of yield measures are commonly used, mass of grapes per vineyard surface, or volume of wine per vineyard surface.[1]
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 wineappellations.
In most ofEurope, yield is measured inhectoliters perhectare, i.e., by the volume of wine. In most of theNew 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 differingwinemaking 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 forwhite wine, 130 kg forred wine, and 140 kg for a mixture of red and white wine.[1]
Thus:[2]
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.
| Yields in selected wine-producing countries in 2007 as national averages[3] | |||
|---|---|---|---|
| Country | Yield (hl/ha)[4] | Vineyard area (1,000 ha) | Wine production (million hl) |
| Italy | 55 | 840 | 45.9 |
| France | 52 | 867 | 45.4 |
| Spain | 30 | 1169 | 34.7 |
| United States | 49 | 409 | 20 |
| Argentina | 65 | 230 | 15 |
| Germany | 103 | 102 | 10.5 |
| South Africa | 73 | 135 | 9.8 |
| Australia | 55 | 174 | 9.6 |
| Portugal | 23 | 248 | 5.8 |
| Austria | 52 | 50 | 2.6 |
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 carefulcanopy management is used.[5] In general, white wine is seen as less sensitive to high yields, and some grape varieties, such asPinot noir, as particularly sensitive to overcropping.[6]
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 ashail orgrey rot. For theBordeaux vintages of the 1980s, it is generally recognized that the most abundant harvests also gave the best vintages.[1][7]
In both France and Italy, the maximum allowed yields are regulated inwine laws, and vary between appellations.
In France, the maximum yields are given in the regulations for eachappellation 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 theplafond 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.[1]
