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?
What is the optimal temperature range for photosynthesis?
18–33°C (64–91°F)
What is the minimum outdoor temperature a vine needs for the flowering and fruit set stage?
Minimum 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:
The next year
What do methoxypyrazines smell like?
Herbaceous / green bell pepper
The breakdown of methoxypyrazines is hindered by:
Cool conditions
What conditions can cause photosynthesis to slow down or stop?
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?
What are the natural factors that affect temperature and sunlight?
Regions at lower latitudes (nearer the Equator) receive:
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 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?
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?
What are some cons to planting on slopes?
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:
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.