D1 Viticulture: The Growing Environment Flashcards
Factors that influence the growing of wine grapes around the world.
What temperature ensures vine dormancy?
Under 10°C / 50°F
At what temperature do winter freeze and/or damage occur to a vine?
-20°C / -4°F
Budburst is stimulated above this temperature.
What else stimulates budburst?
- 10°C (50°F);
- Warm soil temperatures can also stimulate budburst.
What is the optimal temperature range for photosynthesis?
18–33°C (64–91°F)
What is the optimal temperature range for flowering?
Above 17°C / 63°F
What is the optimal temperature range for fruit set?
26–32°C / 79–90°F
Warm temperatures (25°C / 77°F) around the time of fruit set promote increased bud fruitfulness for:
- that same year
- the next year
- the year after next year
The next year
What do methoxypyrazines smell like?
Herbaceous / green bell pepper
The breakdown of methoxypyrazines is hindered by:
- cool conditions
- warm conditions
- soil drainage
Cool conditions
What conditions can cause photosynthesis to slow down or stop?
- Extreme heat, especially when combined with dry conditions;
- Water stress (the vine tries to protect itself by closing its stomata, reducing water vapor loss, but closed stomata can’t take in carbon dioxide which the vine needs for photosynthesis);
- Cold, cloudy conditions.
Even though sunlight is needed for photosynthesis, sunlight doesn’t have to be 100% full, unhindered sunlight for photosynthesis to occur.
It’s only when light levels fall below ___ that sunlight becomes a limiting factor in photosynthesis.
1/3
What are the benefits of having direct sunlight on grapes?
- Promotes development of anthocyanins;
- Reduces methoxypyrazines;
- Enhances accumulation of tannins pre-véraison;
- Enhances polymerization of tannins after véraison (decreasing bitterness);
- Increases levels of aroma precursors and aroma compounds;
- Increases metabolization rate of malic acid in grape respiration, leading to lower acidity levels.
What are the natural factors that affect temperature and sunlight?
- Latitude;
- Altitude;
- Slopes and Aspect;
- Proximity to water;
- Wind;
- Soil characteristics;
- Mist, fog + clouds.
Regions at lower latitudes (nearer the Equator) receive:
- less intense
- more intense
solar radiation than latitudes nearer the poles.
More intense
Solar radiation at the Equator is more powerful because the radiation travels through a smaller section of atmosphere and hits the Earth’s surface at a larger angle (nearer perpendicular).
The number of hours of solar radiation in low latitude regions are similar daylight hours throughout all seasons of the year.
However, regions at high latitudes have ____ summer daylight hours and ____ winter daylight hours.
- Longer summer daylight hours;
- Shorter winter daylight hours.
Longer daylight hours during the summer benefits grapes grown at these cooler latitudes.
Temperature falls by roughly ____ every 100 meter increase in altitude.
0.6°C (1.1°F)
This is why high-elevation sites are advantageous in areas of low latitude.
Conversely, high latitude areas that have relatively low elevation can make for sufficient ripening.
Why do vineyards at high elevations generally have cooler nighttime temperatures than vineyards at low elevations?
The air is thinner at higher elevations, so it holds less moisture which means heat escapes quickly.
At lower elevations, the air in the atmosphere holds more moisture which absorbs some of the energy the soil radiates out (that it had accumulated during the day), so some heat is retained at night.
What is aspect?
The direction a vineyard faces
Why does the importance of aspect and slope steepness increase at high latitudes?
- Solar radiation hits the Earth at a low angle at high latitudes, so an aspect that faces the Equator optimizes heat and light;
- Slope increases the angle (nearer to perpendicular) at which solar radiation hits the Earth’s surface, thereby increasing intensity of heat and light.
Conversely, in warm regions a vineyard whose aspect faces away from the Equator limits the amount of heat and light which can help the grapes retain freshness and acidity.
What are some benefits to planting on slopes?
- Shallow, poor soils;
- Good drainage;
- Provides shelter from bad weather;
- Provides frost protection.
What are some cons to planting on slopes?
- Soil erosion;
- Difficult or impossible to use machinery.
What are some benefits for east-facing slopes?
East-facing slopes see morning sun, which is gentler than afternoon sun, and heats up the atmosphere slowly. This means:
- Air and soil temperatures are at their lowest in the morning and they’re slow to heat up, which extends the hours of vine growth and ripening (an advantage for cool climates);
- Morning dew dries out earlier in east-facing vineyards, reducing the spread of fungal disease.
Describe how areas near bodies of water are able to remain relatively cool.
In the daytime, the water and air above a body of water remain cool, which lowers the average temperature in the surrounding/nearby area.
Air directly above dry land heats up more quickly than air above water, and this warmer air rises. Cool air from above the water is sucked in towards the land replacing the warm air as it rises, resulting in cool, humid afternoon breezes.
How does a body of water keep its surrounding area warmer at night?
Bodies of water release their warmth slowly (as opposed to land, which loses its warmth quickly without solar radiation), so at night the body of water is releasing the heat it acquired during the day.
How can ocean currents influence wine growing areas?
Warm ocean currents like the Gulf Stream can help buoy a cooler or marginal climate, such as Bordeaux;
Cool ocean currents like the California current can help cool down a region that sees high temperatures.
Sunlight reflected off of bodies of water is most advantageous for:
- cool climates
- warm climates
- vineyards at low latitude
Cool climates
What causes El Niño?
Warm water in the western Pacific Ocean that moves eastward along the Equator towards the Caribbean.
What are the effects of El Niño on the east side of the Pacific?
- High levels of rainfall and risk of hurricanes in South America and California due to a warmer eastern Pacific Ocean;
- Disrupted pollination and fruit set from higher rainfall;
- Increased vegetative growth (which can hinder ripening) due to excessive water availability;
- In Washington and Oregon, it brings warmer than average temperatures and drier conditions.
What are the effects of El Niño on the west side of the Pacific (read: in Australia)?
Warmer temperatures and drought conditions, which can cause extreme vine stress and even vine damage.
What causes La Niña?
A cooler-than-average eastern Pacific Ocean
What are the effects of La Niña on the east (United States) and west (Australia) sides of the Pacific?
- In Washington and Oregon, La Niña results in cooler, wetter conditions;
- In California and South America, it results in warmer, drier conditions;
- In Australia, it causes wetter and cooler conditions.
What factors do winds and breezes influence?
- They moderate temperature;
- Lower disease risk because they move humid air out from a vine’s canopy;
- Increase evapotranspiration (which may lead to water stress);
- Strong winds can damage vines and trellising, which can lead to yield reduction and higher labor/equipment costs.
If you, as a grape grower, plant a row of trees near your vineyard to create a windbreak, what do you have to be mindful of?
Not to plant the trees so close to the vineyard that they compete with the vines for nutrients and water.
