3. The Growing Environment Flashcards
Describe how sunshine exposure positively affects grapes.
- enhancing development of anthocyanin (color pigments) in black grapes
- reducing levels of methoxypyrazines
- great accumulation of tannins pre-verasion and promotes tannin polymerization after verasion, which results in reduced bitterness.
- associated with increased levels of favorable aromas and aroma precursors
- warms the grapes, which increases the rate at which malic acid is used up, leading to lower acidity levels.
How is bud burst affected by warm/cold temperatures?
- Temps above 50F stimulate budburts, and budburst is often more successful and uniform if there is a significant rise in temp at this point.
- Warm soil temps also promote bud burst
- Cold temps that bring frost can be very harmful for buds and reduce yields.
How do warm temps affect the following growing season?
Warm temps promote increased bud fruitfulness in the next year, therefore affects the yield in the next growing season.
How do warm temps affect grape ripening?
- Sugar accumulation in the grapes is generally faster at warm temps due to both optimum rates of photosynthesis producing sugars and because increased grape transpiration promotes the movement of sugar into the grape.
- Malic acid degradation is also increased at warm temps
- Mean temps above 70F in the final month of ripening can lead to a rapid loss of acidity, whereas mean temps below 59F can reduce acidity loss to a point that acidity levels in the must are too high.
How do warm/cold temps affect the vine early in the growing season?
Warm- promote successful, uniform flowering and fruit set
Cold-Cold and damp conditions can case problems for flowering and fruit set, therefore reductions in yield and potentially the quality of the grapes and wine.
How do mists, fog, and clouds affect temperature and sunlight?
- sunlight can be so limited that it reduces photosynthesis.
- less solar radiation, temps can be lower, particularly if fog or clouds delay sunshine.
- can slow down sugar accumulation and acid degradation in grapes, which may be beneficial in warm regions or with early-ripening grapes
- increases risk of fungal disease, which in the case of Noble Rot, is a good thing for some regions.
Optimum temp range for photosynthesis?
64-91F
Negative effects of sunshine on grapes?
sunburn
-especially in warm/hot/sunny climates. Some shading is usually beneficial.
Describe how latitude affects temperature and sunlight.
- regions at lower latitudes with receive more solar radiation per year than regions at higher latitudes (poles). This because there is less atmosphere for radiation to travel through. The higher the latitude, the more diffused radiation becomes bc earth’s curve.
- Hours of solar radiation through different times of the year is also determined by latitude. Low latitude areas recieve similar daylight hours (hence heat and sunlight) throughout all seasons. Higher latitude regions have longer daylight hours in the summer vs winter. This permits a longer amount of time over which photosynthesis can take place in the growing season, which is useful bc these regions are usually cooler and longer growing season helps the vine produce enough sugar to ripen grapes.
What is transpiration?
Water vapor diffuses out of the stomata. The loss of water from the cells in the leaf causes water to be pulled upward from the soil, through the roots and the above ground parts of the vine.
What are the 7 natural factors that effect temperature and sunlight?
- Latitude
- Altitude
- Slopes and aspect
- Proximity to water
- Winds
- Characteristics of the soil
- Mist, fog, clouds
Describe the effects of wind on temperature
- have a warming or cooling effect.
- areas near water may experience cool breezes during day, moderating diurnal range.
- valleys can funnel air and lead to stronger winds (think Rhone)
- winds that have travelled over hot land masses bring warm air that heat vineyard area.
How does soil affect temperature?
- drainage of soil, texture, and color all influence the warmth of the soil and the air directly above it.
- free draining soils like sand or stony soils warm up more rapidly than damp soils. Rising soil temps stimulate bud burst and shoot growth.
- desireabkle in cool-climate areas to have free-draining soils to promote early bud burst. But hat also increases the chance of frost damage
- color of soil affects temp. Light colored soils (chalk) reflect some energy from solar radiation into the lower parts of the canopy that are shaded. Beneficial for photosynthesis esp in cool and cloudy areas.
- dark colored (volcanic) soils absorb energy and re-radiate most of it when temps are cooler, like at night. This can be useful in cool climates or for late-ripening grapes.
How do slopes and aspect affect temperature and sunlight?
- increase in slope, especially at high latitudes, equals a more perpendicular angle that sunlight hits the earth therefore increasing the intensity.
- in this respect, slope can make a huge difference on the viability of a vineyard at high latitudes, which grapes can be grown, and the ripeness of those grapes.
- especially if the slop faces the sun (south-facing in northern hemisphere and north-facing in southern)
- East facing slopes get morning sun which heats up the soil and air, which can extend hours of vine growth and ripening, especially in cool climates. Grape canopy dries out earlier in east facing, reducing spread of fungal disease. beneficial for grape quality and yields.
- West facing slopes get afternoon sunshine, which can be too hot in warm climates. Needs moderating effect like wind to alleviate risk of sunburn.
Besides sunlight and temperature, how else are slopes beneficial?
protection from wind and frosts, shallower and poorer soils and better drainage.
