D1C03 The Growing Environment NEW

Question 1

What are important resources needed if the vine is to produce and ripen grapes suitable for making wine.

Answer 1

The amount of warmth, sunlight, water and nutrients and the timing of these key resources within the growth cycle.

Question 2

What viticultural generic aspect will have a defining influence on the wine produced?

Answer 2

In the vast majority of cases, the growing environment and its effect on natural resources will have a defining influence on the wine produced.

The natural resources available to a particular vineyard or even a particular vine depend on the growing environment. In turn, the growing environment is often a function of the positioning of the vineyard site, which is a key reason why delimited geographical indications are so important throughout the world of wine.

Question 3

What is the main source of heat and sunlight?

Answer 3

Solar radiation is the main source of both heat and sunlight and therefore many of the factors that influence one also influence the other.

Question 4

Temperature has a huge influence on vine growth and/or grape ripening in all parts of the vine growth cycle.

Explain the temperature a vine needs in winter….

Answer 4

Cold temperatures (under 10°C) in the winter ensure the dormancy of the vine, however, extreme temperatures (around -20°C) can cause winter freeze and damage the vine.

Question 5

Temperature has a huge influence on vine growth and/or grape ripening in all parts of the vine growth cycle.

Explain the temperature a vine needs at budburst….

Answer 5

Temperatures above 10°C stimulate budburst, and budburst is often more successful and uniform if there is a significant rise in temperature at this point. Warm soil temperatures can also promote budburst. Cold temperatures that bring frost can be very harmful for buds and new growth and can reduce yields substantially.

Question 6

Temperature has a huge influence on vine growth and/or grape ripening in all parts of the vine growth cycle.

Explain the temperature a vine needs at shoot growth….

Answer 6

As the new shoots grow and leaves develop, the vine begins to use photosynthesis to create sugar for energy. The optimum temperature range for photosynthesis is approximately 18–33°C, and hence temperature is not usually a limiting factor at this time.

Question 7

Temperature has a huge influence on vine growth and/or grape ripening in all parts of the vine growth cycle.

Explain the temperature a vine needs at flowering….

Answer 7

Warm temperatures promote successful, uniform flowering (optimum above 17°C) and fruit set (optimum range 26–32°C), whereas cold, damp conditions can cause problems for flowering and fruit set and therefore reductions in yield and potentially quality of the grapes and wine.

Question 8

Temperature has a huge influence on vine growth and/or grape ripening in all parts of the vine growth cycle.

Explain the temperature a vine needs at bud development….

Answer 8

Warm temperatures at this time also promote increased bud fruitfulness (above 25°C is best) in the next year, and therefore affects yields in the next growing season.

Question 9

Temperature has a huge influence on vine growth and/or grape ripening in all parts of the vine growth cycle.

Explain the temperature a vine needs at grape ripening….

Answer 9

Temperature also has an influence on many aspects of grape ripening:

1. Sugar accumulation in the grapes is generally faster at warm temperatures due both optimum rates of photosynthesis producing sugars and because increased grape transpiration promotes the movement of sugar into the grape.
2. Malic acid degradation is also increased at warm temperatures.
3. The effect of temperature on the formation of aroma precursors and aroma compounds is very complex; generally riper aroma/flavours are associated with grapes grown in warmer climates.
4. Cool conditions may hinder the breakdown of methoxypyrazines, which can give herbaceous aromas.
5. In black grapes, anthocyanin synthesis is optimum at 15–25°C (and therefore the development of colour). Tannin synthesis possibly follows the same pattern, but more research is needed.

Question 10

Temperature has a huge influence on vine growth and/or grape ripening in all parts of the vine growth cycle.

Explain the effects of extreme heat during grape ripening…

Answer 10

Extreme heat, especially when paired with dry conditions, can cause photosynthesis to slow or stop, slowing vine growth and grape ripening. This is due to the heat sensitivity of enzymes that catalyse photosynthesis.

In addition, water stress, which is typical in many hot regions, can also cause photosynthesis to slow down or stop due to the shutting of stomata to prevent water loss (see The Effects of Water). The closed stomata limit intake of carbon dioxide, which is needed for photosynthesis.

Question 11

What can lead to the rapid loss of acidity?

Answer 11

in the final month of ripening mean temperatures above 21 Ccan lead to a rapid loss of acidity,

whereas mean temperatures below 15 C can reduce acid loss to a point that acidity levels in the must are too high.

Question 12

How do temperature needs differ for different varieties?

Answer 12

Different grape varieties have different needs and sensitivities regarding temperature.

Late-ripening varieties may need a greater amount of heat through the growing season to ripen sufficiently (both in terms of sugar accumulation and also aroma and tannin ripeness). Early-ripening varieties, such as Pinot Noir and Chardonnay, will need less heat in total and will ripen very early in warm climates.

Question 13

When becomes sunlight the limiting factor for photosynthesis?

Answer 13

Full sunshine (intense sunlight, not blocked by cloud) is not required, and generally amount of light only becomes the limiting factor to rate of photosynthesis if light levels drop below one third of full sunshine.

Hence, fog can slow photosynthesis but an average cloudy day will not.

Question 14

Grape exposure to sunshine has a number of effects, what are these (positive) effects of sunshine on the vine?

Answer 14

1. enhancing the development of anthocyanins (colour pigments) in black grapes and the reduction of methoxypyrazines.
2. Sunshine on the grapes leads to greater accumulation of tannins pre-véraison and promotes tannins polymerisation after véraison, and therefore less bitterness.
3. It is also associated with increased levels of some favourable aroma precursors and aroma compounds.
4. Sunshine also warms the grapes and because of this increases the rate at which malic acid is used up in grape respiration, leading to lower acidity levels.

Question 15

What class of aroma compounds is responsible for many of the fruity and floral aromas in wines?

Answer 15

Terpenes are responsible for many of the fruity and floral aromas in wines, such as the grapey aromas found in Muscat.

Question 16

What could be the effect of prolonged periods of sunshine and hot temperatures?

Answer 16

Prolonged periods of sunshine and hot temperatures can lead to sunburn on sun-exposed grapes, which has a negative effect on grape quality and yields

Question 17

What can be beneficial in climates that are warm or hot and/or very sunny?

Answer 17

In climates that are warm or hot and/or very sunny, some shading of the fruit is usually beneficial.

The grape grower may ensure the grapes are covered with one thin layer of leaves, so that the bunches receive dappled sunshine.

Question 18

Grape vine exposure to sunshine has a number of effects, explain the sunshine a vine needs late spring / early summer

Answer 18

Sunshine in late spring / early summer is associated with successful fruit set and the exposure of compound buds to sunshine promotes bud fruitfulness in next year’s growing season.

Question 19

What are examples of low latitude areas under vine?

Answer 19

Mendoza, South Africa, New South Wales

Higher latitude areas, e.g. nearer the Poles, are northern France and Germany.

Question 20

What is the effect of latitude on solar radiation?

Answer 20

Regions nearer the Equator - having a lower latitude - receive more intense solar radiation and receive more per annum than those nearer the poles.

Question 21

Explain the effect of latitude on solar radiation…

Answer 21

Solar radiation is adsorbed (held by water droplets, dust and ozone) and scattered as it travels through the Earth’s atmosphere, decreasing its intensity.

The curvature of the Earth means that nearer the poles solar radiation must travel through a larger section of atmosphere to reach the Earths surface. It also means that the radiation hits the Earth at a low angle, so the radiation is spread over a larger area (it is more diffuse).

By contrast, at the Equator the radiation travels through a smaller section of atmosphere and hits the Earths surface at a larger angle (nearer perpendicular), so that solar radiation here is more powerful.

Question 22

What are the effects of lower lattitudes on the grapes grown there?

Answer 22

If all other factors were equal, temperatures would be warmer and sunshine more intense in regions at lower latitudes than those at higher latitudes.

Very broadly speaking, this means that grapes grown at lower latitudes can have higher levels of sugar, lower levels of acidity, riper aromas and, in black grapes, higher but riper tannins and more colour intensity than those at higher latitudes.

Question 23

What helps grapegrowing in high latitude regions, despite the low temperatures?

Answer 23

High latitude regions have longer daylight hours in the summer and shorter daylight hours in the winter. This permits a longer duration of time over which photosynthesis can take place in the growing season. Given the cooler temperatures in these locations, this can be useful in helping the vine to produce enough sugar for ripening grapes.

Low latitude regions receive similar daylight hours (and hence heat and sunlight) throughout all seasons of the year.

Question 24

Between what latitudes can grapes in generally grow?

Answer 24

It is generally said that grapes for wine production can grow between 30 and 50 degrees latitude on each side of the Equator. There are exceptions to this.

However, regions nearer the Equator are usually too hot during the day. Vines transpire to regulate their temperature and if water is not readily available, this can cause water stress. Grapes can also suffer from sunburn. Regions near the poles are simply not warm enough during the growing season (despite long daylight hours) for enough sugar to accumulate in the grapes.

Question 25

What is the effect of altitude on temperature?

Answer 25

Temperature falls by approximately 0.6 C over every 100 m increase in altitude.

High-altitude sites can therefore be favourable in areas of low latitude that would otherwise be too hot. There are vineyards in Salta (a low latitude region) planted at up to approximately 3000 m above sea level, and here grapes may struggle to ripen sufficiently every year.

By comparison, many of the best vineyard sites in high latitude areas, such as Burgundy and Loire Valley, are at relatively low altitudes, as otherwise temperatures would be too low for sufficient ripening.

Question 26

What is the effect of high altitudes on sunshine? And what is the effect on grape berry development?

Answer 26

Sunshine is more intense at high altitudes than low altitudes because the solar radiation travels through less atmosphere before it reaches these sites. Ultraviolet radiation, (radiation with a lower wavelength than visible sunlight) is also greater at higher altitudes. Both of these factors are thought to promote anthocyanin and tannin synthesis.

Question 27

What is the effect of altitude on the diurnal range?

Answer 27

High-altitude sites often have a high diurnal range (the difference between day and night temperatures).

The ground absorbs energy from solar radiation during the day and releases energy into the atmosphere during the night. At lower altitudes the air in the atmosphere (particularly the water vapour) absorbs some of this energy, meaning some heat is retained at night. At high altitudes the air is thinner and holds less moisture and therefore heat rapidly escapes, leading to relatively cool night-time temperatures.

In warm climates, high diurnal range can be beneficial for the retention of acidity during grape ripening.

Question 28

Define diurnal range?

Answer 28

The diurnal range of a region or vineyard site is the average difference between day-time and night-time temperatures.

Regions with continental climates or at high altitude tend to have higher diurnal ranges (larger difference between day and night temperatures), whereas regions near a large body of water tend to have lower diurnal ranges (smaller difference between day and night temperatures).

Question 29

What is the effect of a large diurnal range in warm or hot climates?

Answer 29

In warm or hot climates, such as those found in Mendoza or Ribera del Duero, a large diurnal range is often thought to be favourable. In these climates, a relatively cool period during the night can slow the respiration of malic acid and be beneficial for the formation of anthocyanins (day-time temperatures are too hot).

Question 30

What is the effect of a low diurnal range in cool or moderate climates?

Answer 30

In cool and moderate climates, such as Mornington Peninsula or Mosel, a low diurnal range may be favourable so that night-time temperatures still allow ripening (e.g. acid degradation, anthocyanin synthesis) to continue, which may be needed for grapes to ripen sufficiently.

It is also thought that night-time temperatures can have some influence on aroma compounds. For example, warmer night temperatures are associated with a greater breakdown of methoxypyrazines, which may be important in cool climates, and cooler temperatures are associated with a greater retention of some other compounds, such as rotundone. Given the number of aroma compounds and precursors in grapes and their interactions such relationships are complex.

Question 31

What is aspect?

Answer 31

The particular direction that vineyards planted on slopes will face.

Question 32

What is the impact of latitude on the importance of aspect?

Answer 32

The importance of aspect and the steepness of the slope increases at high latitudes. This is because solar radiation hits the Earth at a low angle at high latitudes.

In the context of the vine growth cycle, the angle is lowest in the spring and autumn (compared to the summer). The slope compensates the earths curveture, increases the angle (nearer to perpendicular) at which the solar radiation hits the Earth’s surface, hence increasing the intensity of heat and light.

The amount of warmth is also often a limiting factor in high latitude areas, so a slope can make a marked difference on the viability of a vineyard, what grape varieties that can be grown there and the ripeness of those grapes. Extra warmth and light during spring and autumn extend the viable growing season for vines grown on slopes that face towards the sun.

As evidence of this, in the cool climate regions of Burgundy and Alsace, the Grand Cru sites giving wines with greater ripeness and concentration are usually positioned on south-east facing slopes, while the vineyards of the generic appellation are found on the flat.

Question 33

How can grapegrowers benefit from aspect in warm climates?

Answer 33

In warm climates, it may be desirable to limit the amount of heat and light. Planting on slopes that face away from the sun throughout most of the day can help achieve this. This may allow the grape grower to grow earlier-ripening grape varieties or produce wines with less alcohol and more acidity than would otherwise be the case at that latitude. For example, in Stellenbosch, white grape varieties are sometimes planted on south-facing slopes so that the grapes retain refreshing acidity.

Question 34

What is the impact of east facing slopes on grapegrowing?

Answer 34

Slopes facing east benefit from morning sunshine that can heat up the atmosphere when air and soil temperatures are at their lowest. This can extend the hours of vine growth and grape ripening each day, especially in cool climates. The grape canopy, which can be covered with dew in the morning, also dries out earlier in east-facing vineyards, reducing the spread of fungal disease, which is beneficial for grape quality and yields.

Slopes that face west receive the afternoon sun and may become too hot, especially in warm climates, and risk of sunburnt grapes is increased (see Sunburn in Hazards). However, in areas with coasts to the west, e.g. California and Western Australia, cool afternoon sea breezes may alleviate this.

Question 35

What are benefits of grapegrowing on slopes?

Answer 35

Slopes can provide additional benefits, including shallower, poorer soils and better drainage.

Slopes can also provide shelter from winds and rain, and protection from frosts (air movement down the slope prevents frosts from forming).

However, soil erosion and inability to use machinery on steep slopes can be problematic.

Question 36

Explain the effect of proximity to water on local a/o microclimate.

Answer 36

Large bodies of water, such as lakes and seas, can have a significant impact on nearby vineyards. This is because water heats up and cools down more slowly than dry land. During the day, the water and the air above a body of water remains relatively cool, and lowers the average daytime temperature in the local area. Air directly above dry land heats up more quickly than that above the water, and this warm air rises. Cool air from above the water is drawn to the land to replace the warm air as it rises, resulting in cool, humid afternoon breezes.

The opposite happens at night. The water retains the warmth gained during the day, whereas, without solar radiation, the land loses heat relatively quickly. The warmth of the body of water keeps the local area warmer, e.g. a higher nighttime temperature. The same effect can be experienced over the year, with large bodies of water giving cooler summers and milder winters.