Chapter 3 - The Growing Environment - Part 1 Sunlight and Temperature Flashcards
Temp needed to ensure dormancy
Temp that causes winter freeze/ damage to the vines
Temp that will kill the vine
Under 10C
Around -20C
Below -25C
Temp that stimulates budburst
Above 10C
Temp range for shoots and leaf growth and for photosynthesis
18-33C
Temp for uniform flowering
Above 17C
Temp for fruit set
26-32C
Temp for bud fruitfulness
Above 25C
Temp that can cause rapid loss of acidity in final month of ripening
Above 21C
Temp that can reduce acid loss to the point that acidity levels are too high
Below 15C
Temp for optimal anthocyanin synthesis
15-25C
How does sunlight affect grape growth?
Enhances development of anthocyanins
Reduces levels of methoxypyrazines
Greater accumulation of tannins pre-veraison and tannin polymerization after veraison
Increases levels of favorable aroma precursors/compounds
Increases rate of malic acid use (good and bad)
Promotes successful fruit set
Promotes budfruitfulness
Amount of sunlight actually needed. What does it affect below that threshold?
1/3 of full sunshine - below that it affects photosynthesis
Cons of too much sunlight
Sunburn - affects quality and yield
Why are regions in lower latitudes warmer and have more sunshine, generally?
Solar radiation hits at a higher angle and travels thru a smaller section of atmosphere
Low latitude regions receive similar daylight hours throughout the year. High latitude regions have longer daylight hours in the summer and shorter in winter
What is the ideal latitude range for viticulture?
30-50deg
What does high-altitude sites have that low altitude sites don’t, generally?
Lower temp (temp falls 0.6C over every 100m increase More intense solar radiation - radiation tarvels thru less atmosphere to reach the site - promotes anthocyanin and tannin synthesis More ultraviolet radiation - promotes anthocyanin and tannin synthesis High diurnal range - thinner air holds less moisture and therefore heat escapes rapidly
How does aspect help viticulture in high latitudes?
Increases the angle at whcih solar radiation hits the earth’s surface, increasing hte heat and light intensity
What are the benefits to east facing vineyards?
Direct morning sun heats up first and gets more sunlight hours in
Direct morning sun dries environment and prevents fungal disease from spreading
General pros/cons of slopes
Pros: Shallower, poorer soil Better drainage Shelter from winds and rains Protection from frost (cold air moves down)
Cons:
Machinery hard to use/not possible to be used
Soil erosion
How does being proximal to water help the Finger Lakes and Carneros?
Finger Lakes:
Lake milds out winters by retaining and warming up the land by it - cool summers, mild winters
Also prevents frost by providing constant air movement
Carneros:
Cooling oceanic wind in the afternoon because water remains relatively cool compared to land
Water heats up and cools down slower than dry land
Warming oceanic currant that warms up Bordeaux
Gulf Stream
Cooling oceanic current that cools down Oregon
Califonia current
Pros/cons of winds and breezes
Reduces humidity and stagnant air - good for fungal disease prevention
Valleys that face the coast help winds travel farther inland (petaluma gap)
Increases evapotranspiration for the vine
Strong winds can damage vines and trellising
Winds that travel over hot land masses bring warm air (zonda) - good and bad
What factors of soil affect its and the air’s temperature ?
Drainage
Texture
Color
What types of soil warm up quicker and waht are the benefits?
Free draining soils - sandy and stony soils
Encourages breakdown of starch, stimulating budburst and shoot growth (therefore wanted in cool climates but can also inc risk to spring frost)
Light vs Dark colored soil
Light colored (ie chalk) reflect energy from solar radiation into lower parts of the canopy - beneficial for photosynthesis and grape ripening as these parts may be shaded. In warm climates, can lead to unwanted temp increases though
Dark colored soil (ie volcanic soil) absorb energy and reradiate when the temp cools like at night
Useful for cool climates or late-ripening grapes - allows color dev and acid degradation to continue into the night
Impacts of mist and fog
Slows down sugar accumulation and acid degradation
Increases humidity - good for noble rot and fungal disease
Diurnal Range definition
Benefit of large diurnal in warm climates?
Benefit of low diurnals in cool climates?
Average difference between day and night time temperatures
Slows down respiration of malic acid and beneficial for anthocyanin formation (too hot during the day)
Grapes can continue to ripen at night - acid degradation, anthocyanin synthesis, etc