Flashcards in Viti 1: The Growing Environment Deck (49)
Photosynthesis in a nutshell:
Sunlight energy allows chlorophyll (leaves) to combine water and CO2 to make sucrose, later transformed into glucose and fructose in the vine itself.
Larger carbohydrates e.g. cellulose (building the vine), tannins, acids and flavour molecules.
Dormant below 10 degrees, growth peaks between 22 and 25 degrees. Growth slows above this, as needs outpace its speed of sugar production. Freeze injury begins at -15, serious at -20 and fatal at -25.
Reduces as the angle at which it hits the ground reduces from 90 degrees to 0. Light beams have to travel through greater thickness of atmosphere.
Sites facing east:
Rays less scattered in morning as earth has cooled and dust has settled.
Sites facing west:
BAD! 1. Sunlight scattered by dust settled after being lifted by warming air. 2. They face damper and cooler weather conditions.
Soils on slopes:
Poorer, more coarse and better drained. Moderates vigour. BUT - lifts costs and runs risk of erosion. Isolated hills often best as they avoid descending cold air from main slopes (e.g. hill of Corton, Montagne de Reims).
Act as windbreaks, store heat and reduce erosion. BUT - increase humidity and decrease temperature of mesoclimate and can harbour birds.
Vigorous canopy can:
Reduce flower initiation and berry set (shading), give more acidity (cooling), reduce sugars (humidity and shading) and encourage competition between shoot tips and berries (stunted ripening).
Temperature's impact on yield:
Rate of growth, number of flower clusters produced, their size and the success of setting into berries.
Temperature's impact on quality:
Level of yield, accumulation of sugars, reduction of acidity and development of aromas.
Amerine and Winkler's heat summation system:
1944. Mean temp. for month, subtracting 10 degrees and multiply by number of days in month. Sums are totalled for growing season months to give figures in Growing Degree Days (GDD). 1370, 1370-1650, 1650-1930, 1930-2200 and over 2200. Sunlight, humidity and temp. variability not taken into account - vine growth slows above 30 degrees.
Prevailing Australian heat summation system:
Smart and Dry
500mm/year in cool climate, up to 750mm/year in hotter climate.
Calculation for rainfall:
1mm of rainfall on 1 square metre is 1 litre.
Substance responsible for 'green' flavours:
Regions of higher latitude:
Longer days, longer ripening window.
Sunshine's impact on vine:
Bud viability, flower initiation, berry ripening, cane maturation and rate of photosynthesis.
Sunshine hours needed for ripe fruit:
A minimum of 1250 hours. Amount of available sunshine will decrease by up to 10% if near to town or city (pollution).
Berry scorching most likely:
After leaf stripping or spray application.
Annual temp. and altitude:
Mean annual temp. decreases 0.6 deg with every 100 metre rise above sea level. Loss of 105 GDD a year.
TOSMAWA! Texture, organic matter content, structure, mineral content, air and water availability and acidity/alkalinity.
Diameter measured in mm. CSFSG: clay, silt, fine sand, sand and gravel. 0, 0.002, 0.02, 0.2, 2 and 2+
Hold more moisture, made of small particles. Negatively charged, will hold more minerals. They stay cool, they swell and crack, they damage roots, they get sticky and their structure deteriorates as they're worked.
Balance of clay, silt and sand. Clay's nutrient holding and drainage of sand.
Good drainage and encourage vine to grow deeper roots to find consistent water supplies. Also warm up more quickly.
Sedimentary, rich in calcium carbonate, alkaline (usually) and free-draining.
Like limestone, but less dense. Drains very well.
High in magnesium, sedimentary.