The Growing Environment - Temperature and Sunlight Flashcards
What are the 4 key resources of the growing environment?
- Sunlight
- Warmth
- Water
- Nutrients
What is the main source of both heat and sunlight?
Solar Radiation
Name 6 positive effects that sunshine exposure has on grapes.
- Enhances the development of anthocyanins (colour pigments) in black grapes
- Reduces methoxypyrazines
- Promotes accumulation of tannins pre-véraison
- Promotes tannins polymerisation after véraison (less bitterness)
- Promotes favourable aroma precursors and aroma compounds
- Increases the rate at which malic acid is used up in grape respiration (lower acidity levels)
Name a weather condition that can slow photosynthesis (other than lack of sun or water stress).
Fog
Name 6 positive effects that sunshine exposure has on grapes.
- Enhances the development of anthocyanins (colour pigments) in black grapes
- Reduces methoxypyrazines
- Promotes accumulation of tannins pre-véraison
- Promotes tannins polymerisation after véraison (less bitterness)
- Promotes favourable aroma precursors and aroma compounds
- Increases the rate at which malic acid is used up in grape respiration (lower acidity levels)
What negative effects does sunshine exposure have on grapes?
- Can lead to sunburn on sun-exposed grapes, which has a negative effect on grape quality and yields
Name 2 reasons sunshine in late spring / early summer is beneficial.
- Associated with successful fruit set
- The exposure of compound buds to sunshine promotes bud fruitfulness in next year’s growing season
Which will receive MORE solar radiation per annum: regions at lower latitudes (nearer the Equator) OR regions at higher latitudes (nearer the Poles)?
Regions at lower latitudes (nearer the Equator)
Why do regions nearer to the Equator receive more intense solar radiation than those nearer the poles?
- Solar radiation is adsorbed 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 Earth’s surface.
- Radiation hits the Earth at a low angle near the poles (due to curvature), so the radiation is spread over a larger area
How does latitude effect hours of daylight?
- Low latitude regions receive similar daylight hours (and hence heat and sunlight) throughout all seasons of the year.
- High latitude regions have longer daylight hours in the summer and shorter daylight hours in the winter.
What is the target latitude range for grapes for wine production?
Between 30° and 50° latitude on each side of the Equator
What issues would regions closer than 30° to the equator run into?
- Too hot during the day
- Water stress
- Sunburn
What issues would regions farther than 50° to the equator run into?
- Simply not warm enough during the growing season (despite long daylight hours) for enough sugar to accumulate in the grapes
Give an example of a low latitude region whose altitude allows it to be successful in grape growing.
- Salta Province in Argentina (3000 m above sea level)
- Yunnan Province, China
- Tarija, Bolivia. With vineyards at 1,850m, this is one of the highest altitude wine regions in the world
Is sunshine is more intense at high altitudes or low altitudes? Why?
- High altitudes
- Because the solar radiation travels through less atmosphere before it reaches these sites
Name 7 natural factors that effect temperature and sunlight.
- Latitude
- Altitude
- Slopes/Aspect
- Proximity to Water
- Winds
- Characteristics of the soil
- Fogs, Mists, Clouds
What is aspect?
The direction a particular slope faces
Vineyards at what aspect receive the most solar radiation?
- Vineyards that face the sun throughout most of the day (south-facing in the northern hemisphere) (north-facing in the southern hemisphere)
Is the aspect and the steepness of the slope more important at higher or lower latitudes?
- Higher
- Slope increases the angle (nearer to perpendicular) at which the solar radiation hits the Earth, increasing intensity of heat and light
Name some cool climate regions where slope is crucial.
- Burgundy Gran Cru and Alsace Grand Cru (south-east facing slopes)
- Piedmont, Barolo (Sorí)
How might one limit the amount of heat and light in warm climates?
Planting on slopes that face away from the sun throughout most of the day.
Name 1 warm climate region where slope is crucial.
Stellenbosch (south-facing slopes to retain acidity)
What are the benefits of east-facing slopes?
- Morning sunshine heats up the atmosphere when air and soil temperatures are at their lowest.
- Extends the hours of vine growth and grape ripening each day, especially in cool climates
- The grape canopy (dew-y in the morning) dries out earlier, reducing the spread of fungal disease
What is problematic about west-facing slopes?
- Afternoon sun
- May become too hot, especially in warm climates
- Increases risk of sunburnt grapes
- Mitigate: in areas with coasts to the west, e.g. California and Western Australia, cool afternoon sea breezes
Aside from proximity to sunlight, what 4 other benefits can slopes provide?
- Shallower, poorer soils
- Better drainage
- Shelter from winds and rains
- Protection from frost
What are some of the problems with slopes?
- Soil erosion
- Inability to use machinery on steep slopes
How can a large body of water impact nearby vineyards during the day?
During the day, the water and the air above a body of water remains relatively cool, and lowers the average temperature in the local area.
How can a large body of water impact nearby vineyards overnight?
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.