Quiz - The Growing Environment Flashcards
What does a vine need to survive?
- Sun and radiation from soil
- Sun and reflection from water
- Atmosphere
- Rainfall and irrigation
- Humus and fertiliser
Below which temperature will a vine go into dormancy?
10°C / 50°F
What is the optimum temperature range for photosynthesis to begin, thereby creating sugar for subsequent flowering and grape growth?
18–33°C / 64–91°F
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 (November – March):
* Vines are typically dormant, when the temperatures are below 10°C.
* If temperatures are below -20°C vines get severely damaged.
* Temperatures below -25°C will kill most vitis vinifera.
Budburst (March – April)
* During budburst the temperature should be above 10°C
* There are early budding varieties that bud at a temperature slightly lower than 10°C, e.g. Chardonnay, Pinot Noir, Merlot and Grenache.
* There are also late budding varieties that bud at temperatures slightly above 10°C such as Sauvignon Blanc, Cabernet Sauvignon and Syrah
* Late budding varieties are less at risk of spring frosts
Shoot and Leaf Growth (March – July)
* During shoot and leaf growth, warm temperatures and plenty of sunshine contribute to a healthy growth of the vine.
* Lower temperatures can limit photosynthesis and lead to stunted shoot growth, i.e. small, weak shoots, a reduction in leaf number or smaller leaves, inflorescences that do not flower properly and grape bunches that do not ripen fully.
Flowering and Fruit Set (May – June)
* For best flowering and fruit set, temperatures above 25°C are required.
* A minimum temperature of 17°C is favorable for successful flowering.
* Pollen germination requires warm temperatures (optimal at 26-32°C)
* Lower temperatures ..
* * can limit bud fruitfulness (the number of inflorescences that will develop from a bud) in the next growing season and thus have a substantial influence on the next year’s yield. There is some variation between grape varieties. Riesling can form potentially fruitful buds at relatively low temperatures making it well-suited to cool climates
* * can lengthen the duration of flowering having a consequential negative effect on the evenness of grape ripening.
* * can negatively affect pollen tube growth and this can result in irregular fruit set (coulure, millerandage) and is a key cause for poor yields in cool climates.
Grape Development (June – September)
* During ripening, photosynthesis can take place at a maximum rate at temperatures between 18-33°C.
* Lower temperatures lower the rate of photosynthesis reducing the build-up of the sugar level in the grape.
* By contrast, very hot, dry conditions can lead to extreme water stress which causes photosynthesis to slow down or stop and thus hinder accumulation of sugars in the grape.
* In warm conditions the sugar accumulation can be too rapid and reach high levels before aromas/flavors and tannins have developed fully.
* Mean temperatures above 21°C in the final month of ripening can lead to a rapid loss of acidity whereas mean temperatures below 15°C can reduce acid loss to a point that acidity levels in a must are too high
* During ripening methoxypyrazine levels fall whereas terpene and anthocyanin levels increase with rising temperature
* aroma compounds and precursors develop differently depending on the temperature
Harvesting (September – October)
* 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 during grape development.
Terpenes
What type of acid is considerably used up during vine respiration?
The depletion of this acid leads to lower grape acidity levels.
malic acid
True or false?
Regions at higher latitudes receive more solar radiation per annum than regions at lower latitudes.
False
All factors being equal, grapes grown at low latitudes will have different characteristics to those grown at high latitudes.
Describe the typical characteristics of black grapes grown at low latitudes.
In low latitudes:
1. More color intensity
2. Riper tannins
3. Higher tannin levels
4. Lower acidity levels
5. Riper aromas
6. Higher sugar levels
What are the main differences between high and low altitudes?
- By approximately every 100 meter increase in altitude, the temperature drops by 0.6°C (1.1°F). Therefore, vineyard sites at high altitude can be used in areas of low latitude that would otherwise be too hot.
- Sunshine is more intense at high altitudes than low altitudes. This is because the solar radiation travels through less atmosphere before it reaches the vineyard site.
- Ultraviolet radiation (radiation with a lower wavelength than visible sunlight) is also greater at higher altitudes.
- There is often high diurnal range in high-altitude sites and the air is thinner and holds less moisture at high altitudes.
What is the correct definition of diurnal range?
The average difference between day-time and night-time temperatures.
Which styles of wine rely on the vineyards being located close to bodies of water?
- Sauternes
- Tokaji
What is the definition of evapotranspiration rate?
The amount of transpiration from the vine, combined with the evaporation of water from the soil surface.
Briefly describe the roles of nitrogen, potassium, phosphorous, calcium and magnesium in healthy vine development.
Nitrogen
* essential for wine growth
* main component of proteins and chlorophyll
* too much nitrogen causes excessive vegetative growth to the detriment of ripening the grapes
* too little nitrogen results in reduced vigor and yellowing of wine leaves and impact on fermentation
* vines with a restricted supply of nitrogen tend to produce higher quality grapes
Potassium
* essential for wine growth
* regulates the flow of water in the vine, e.g. by developing the root systems
* very high potassium levels can cause problem in the uptake of magnesium which may lead to reduced yields and poor ripening
* High levels of potassium are linked to high pH
* Low levels of potassium are linked to poorly developed root systems
* Low levels influence sugar accumulation in the grapes, compromising the quality of the harvest and the health of the vine.
Phosphorous
* Important for photosynthesis and well-developed root systems
Calcium
* Important in the structure of plant cells and in photosynthesis
* Deficiency can have negative impact on fruit set
Magnesium
* Key role in photosynthesis – is found in chlorophyll
* Deficiency results in reduced grape yields and poor ripening
Describe the major climate classification models.
Growing Degree Days (GDD)
Split into five ranges. It was originally intended for the vineyard regions in California. Takes into account the mean temperature of a month in the growing season minus 10°C.
Huglin Index (HI)
Split into eight ranges. Takes into account both mean and maximum temperatures and the increased day length experienced at higher latitudes.
Mean Temperature of the Warmest Month
Split into six bands. Uses the mean temperature of either July in the Northern Hemisphere or January in the Southern Hemisphere as well as measures of continentality, humidity and hours of sunshine.
Growing Season Temperature
Split into seven bands. Uses the mean temperature of the whole growing season.
