D1-VITI Quiz on The Growing Environment Flashcards
Quiz on The Growing Environment (Chapter 3) of the D1 Reading 'Wine Production' textbook
Give 5 sources of what a vine needs to survive.
- Humus and Fertilizer as source of Nutrients
- Irrigation and rainfall as source of Water
- The atmosphere as source of CO2
- Sun and reflection from water as source of Sunlight
- Sun and radiation from soil as source of Heat
Below which temperature will a vine go into dormancy?
10°C
What is the optimum temperature range for photosynthesis to begin, thereby creating sugar for subsequent flowering and grape growth.
18–33°C
Briefly describe the importance of temperature during the vine growth cycle. Keeping the following in mind:
The optimum temperatures for each stage of the cycle.
The effect of too much/too little heat at each stage.
The needs of different grape varieties.
Dormancy occurs when the average temperatures fall below 10ºC (50°C). If the temperature does not fall sufficiently to bring on dormancy, the vine will continue to grow and produce a second crop as happens in tropical climates. If the temperature falls below -15°C (5°F) vines can be seriously damaged or killed but if the temperature drops below -25°C (-13°F), most Vitis vinifera will die. Different grape varieties have different temperature tolerances and some hybrids have been bred to withstand winter cold e.g. Vidal.
Budburst is when the buds swell and open after winter dormancy. Average temperatures above 10ºC (50°C) are generally required for budburst to occur. However, some varieties burst just below 10ºC (50°C) e.g. Merlot and some varieties require slightly higher temperatures e.g. Cabernet Sauvignon. If the temperature fluctuates, budburst will be uneven.
Shoot and leaf growth has an optimum temperature of approximately 18-33°C (64-91°F) which is not usually a limiting factor at this time of year.
Flowering & fruit set will happen above 17°C (63°F) but the optimum range is 26-32°C (79-90°F) for uniform flowering and fruitset. At lower temperatures flowering might not be uniform which could lead to a reduction in yield.
Grape development is preferable between an average temperature range of 16-21°C (61-70ºF). Average temperatures above 21ºC (70ºF) in the month leading up to harvest can result in a large decrease in acidity but below average temperatures of 15ºC (59ºF), the acidity may remain very high. In cooler temperatures methoxypyrazines may not breakdown leading to green aromas and flavours in certain grape varieties and anthocyanin synthesis may be slow affecting the colour of red wine. Extreme heat can slow down or stop photosynthesis which will affect grape ripening. Pinot Noir prefers a cooler climate, in warmer climates or in unseasonably warm vintages, the grapes will ripen very early.
Harvest temperatures will depend on what grape variety is being picked and the wine style being produced. The optimum range of temperatures will vary for this reason. Extremes of weather are not preferable, too hot and the berries can shrivel quickly which reduces crop load while concentrating the sugars.
What is the name of the aromas compounds which are responsible for many of the fruity and floral aromas in wines? Production of these aroma compounds can be encouraged by exposure to sunshine pre-vérasion.
Terpenes
Exposure to favourable levels of sunshine can promote desirable aroma precursors and aroma compounds such as terpenes. Terpenes create the grapey aromas found in Muscat.
What type of acid is considerably used up during vine respiration? The depletion of this acid leads to lower grape acidity levels.
Malic Acid
High levels of sunshine can also increase the rate at which malic acid decreases in the grapes.
Regions at higher latitudes receive more solar radiation per annum than regions at lower latitudes. True or false?
False
Regions nearer the Equator receive more intense solar radiation than those nearer the poles. The curvature of the Earth means that nearer the poles solar radiation must travel through a larger section of atmosphere to reach the Earth’s surface.
All factors being equal, grapes grown at low latitudes will have different characteristics to those grown at high latitudes. Give the typical characteristics of black grapes grown at low (versus high) latitudes.
- Higher sugar levels
- More colour intensity
- Riper aromas
- Riper tannin
- Lower acidity levels
- Higher tannin levels
Between what latitudes on either side of the Equator are grapes for wine production generally grown?
30° - 50°
There are regions where this range is an exception, particularly where regions near the Equator are too hot during the day.
By approximately every 100 metre increase in altitude, the temperature drops by how much?
0.6°C
Therefore, vineyard sites at altitude can be used in areas of latitude that would otherwise be too hot?
high altitude
low latitude
Sunshine is more intense at altitudes than at altitudes?
high altitude
Why is sunshine more intense at high altitudes?
This is because the solar radiation travels through less atmosphere before it reaches the vineyard site.
What radiation is also greater at higher altitudes?
Ultraviolet
There is often diurnal range in high-altitude sites and the air is thinner and holds less moisture at altitudes
high diurnal range
less moisture at high altitudes
