The Growing Environment Flashcards
The effects of Temperature
Under 50F causes dormancy
Above 50 stimulates Budburst- warm soils can also promote
Photosynthesis optimally works at 64-91F to create sugar for energy for vigor
Above 63F promotes successful even flowering - above 77F increases bud fruitfulness (affecting next years yields)
Sugar accumulation in grapes fast in warmer areas
Malic acid degradation faster in warm
Extreme heat/water stress can shut down photosynthesis
The effects of Temperature
Under 50F causes dormancy
Above 50 stimulates Budburst- warm soils can also promote
Photosynthesis optimally works at 64-91F to create sugar for energy for vigor
Above 63F promotes successful even flowering - above 77F increases bud fruitfulness (affecting next years yields)
Sugar accumulation in grapes fast in warmer areas
Malic acid degradation faster in warm
Extreme heat/water stress can shut down photosynthesis
The effects of sunlight
Needed for photosynthesis
Light levels below 1/3 full sun can slow (fog)
Grape exposure to sun enhances anthocyanins and reduces methoxypyrazines, increases tannin accumulation pre veraison and promotes tannin polymerization after (less bitter)
Increases terpenes
Lowers acid levels by speeding up Malic acid metabolization
Can sunburn grapes - some shadin beneficial in hot/sunny regions
Natural factors that influence temp and sunlight
Latitude- lower latitude = more and more intense sunlight and number of hours of sunlight (high latitude has longer summer daylight hours - lengthening the ripening
Altitude- temps fall 1*F for every 300’ meaning high altitude can make low latitude viable
Slopes and aspect- sun facing (S in northern hemisphere and N in Southern hemisphere) receive more solar radiation than opposite. Importance of aspect increases at high latitudes due to low angle of sunlight- slope increases angle, increasing intensity. East facing warm up faster and stay warm longer, also dry out faster.
Proximity to water - water absorbs and releases heat to extend growth season - positive for both warm and cool regions to moderate temps. Ocean currents- gulf in Bordeaux vs cold Pacific current in Oregon
Wind- warming or cooling affect
Characteristics of soil- drainage/texture/color influence warmth of soil and air above it
Mist, fog, clouds- limit sunlight and reduce photosynthesis, lowers temperature
El Niño vs La Niña
Nino- warm water in pacific moves along equator towards Caribbean. Eastern pacific becomes warmer and means high rainfall for CA/SA - disrupt pollination and fruit set brings warmer/drier conditions to WA/OR - drought
Nina- Pacific Ocean cooler than avg - cooler and wetter in WA/OR and Australia- warmer drier in CA/SA
The effects of Water
Vines need a min 500mm rainfall in cool climate and 750mm in warm
Lack of water shuts stomata and stops photosynthesis and nutrient uptake
Easily accessible water in late spring/early summer encourages vigor not grape development- delays and compromises ripening
Too much water at end of ripening dilutes/bursts grapes- too little inhibits full ripening
Hail/rain hazards
Bodies of water moderate temps fall
Natural factors that affect water availability
Rainfall
Characteristics of soil - drainage and topography (less penetration on slopes- erosion)
Evapotranspiration rate- rate at which water is no longer available to vine - dependent on temperature and humidity
Important grape nutrients
Nitrogen
Potassium
Phosphorus
Calcium
Magnesium
Nitrogen
Component of protein and chlorophyll
Too much causes vigor/shades fruit or buds/ poor ventilation. Too little reduces vigor and yellows leaves
Needed in grape for alcoholic fermentation
Potassium
Regulates flow of water in vine
Too high and can stunt magnesium uptake - reducing yields and poor ripening and high potassium in grapes have high pH
Low potassium leads to low sugar accumulation and poor vine growth
Phosphorus
Too little leads to poorly developed root systems, reduced vine growth, lower yields
Calcium
Too little negatively influences fruit set
Magnesium
Too little reduced grape yields and poor ripening
Natural factors that effect nutrient availability
Nutrients dissolve in water taken up by roots
pH affects availability (high pH like limestone has poor iron uptake and can cause chlorosis)
Organic nutrient compounds from manure or compost must be broken down into inorganic compounds for vine availability via organisms that live in soil (mineralization)
Different soil textures vary in nutrient holding capacity- sandy soils poor
Topography- slopes thinner
Soil texture
Describes proportions of mineral particles of sand, silt, and clay
Loam - moderate proportion of all three
