D1: The growing environment 4 Flashcards
What a vine needs:
1) heat: factors affecting heat:
- Latitude
- altitude
- ocean currents
- fog
- soil
- aspect
- continentality and diurnal range
Temp hazards:
- Winter
- spring frost (heaters, wind machines, sprinklers, thoughtful vineyard design
2) Sunlight: factors affecting sunlight:
- latitude
- seas and lakes
- aspect
3) water:
- rainfall
- irrigation: drip, sprinklers, flood
hazards:
- drought
- too much water
- hail
4) soil and nutrients
- chlorosys: lack of nutrients
Warm and light are critical for vine growth and grape formation and ripening. teloerature in particular:
Thought to have a very significant effect on vine functioning
— and have a huge influence on potential wine style and quality (and indeed whether grapes can ripen at all)
Solar radiation is the main source of both heat and sunlight and therefore many of the factors that influence one, also influence the other.
true that
temp influence: cold temp:
under 10°c/ 50°f
- in winter ensures the dormacy of the vine
- extreme temp -20°/-4F, can cause winter freeze and damage the vine
Temp influence: above 10°c 50°f
a) stimulate budburst
- - budburst is more succesful and uniform if there is a significant rise in temp at ths point (continentally)
b) warm soil temp also promote budburst
- — cold temp that bring frost can be harmful for buds (sprinklers, windmachines, heaters)
- and reduce yield substantially
as the new shoots grow and leaves develop:
the vine uses photosynthesis to create sugar for energy and support the growth
optimal range:
- 18-33°c
- 64-91°f
Warm temp promote succesful uniform flowering and fruit set
opt above 17°C 63°f
op range 26-32/ 79-90
– cold damp conditions can cause problems for flowering and fruit set and therefore reductions in yiels and potentially quality of grapes and wine
warm temp above 25° c 77°F also promote increased bud fruitfullness in the next year:
compound buds develop the buds for shoots the next growing year, warm temp above 25°c is best and therefore affects the yields in the next growing season
temp influence on many aspects of grape ripening:
1) sugar accumulation in the grapes is generally faster at warm temperatures due both optimum rates of
- photosynthesis producing sugar and transport via pheole to grape
- grape transpirate water so sugar increase
2) malic acid degradation is also increased at warm temp, because after the sugar, the malic acids transpirates
- - mean temp of 21° 70°F in the last month can decrease the amount of acid
- - mean temp of 15°c (59°f Can reduce acid loss to a point that acidity levels in must are too high
3) aromas compounds and percussors are complex:
- riper aromas: warmer condition
- cool conditions may hinder the breakdown of methoxypyrazines, which gives herbaceous aromas
4) in black grapes anthocyanin synthesis (and therefore the development of colour) is opt at 15-25°C 59-77°F
What causes extreme heat and dry conditions to the vine?
1) can cause photosynthesis to slow or stop, slowing vine growth and grape ripening
- - this due the heat sensivity of the enzymes that catalyse photosynhesis
2) water stress can also cause photosynthesis to slow down or stop due the shutting of stomata to prevent water stress (stomata evaporates O2 and inhale CO2 to let the photosynthesis begin:
6CO2+6H2o+ light energy=
C6H12O6+ 6O2
Different grape varietis have different needs and sensitivities regarding temp:
1) late ripening varieties may need a greater amount of heat through the growing season to ripen suff ( both in terms of sugar and also aroma and tann ripeness
2) early ripening varieties such as PN and chard will need less heat in total and will ripen very early in warm climates
The vine needs sunlight for photosynthesis:
1) which is needed for vine growth and grape berry formation and ripening
2) full sunshine (intense sunshine, not blocked by cloud) is not required
3) at least 1/3 of sunlight is necessary
Grape exposure to sunshine has a number of effects:
1) enhancing the development of anthocyans (colour pigments) in black grapes
2) reduction of methoxypyrazines (herbaceous aroma’s)
3) greater accumulation of tannins pre véraison
4) greater polymerisation after véraison
- – less bitterness
5) it is also associated with increased levels of some favourable aroma percursors and aroma compounds (such as terpenes which are responsible for many of the fruity and floral aromas in wines such as the grapey aromas in muscat)
6) sunshine also warm the grapes and because of this increases the rate at which malic acid is used up in grape respiration
- — leading to lower acidity levels
7) too much sun exposure can lead to sunburn to the sun exposed grapes which have a negative effect on grape quality and yields
- — climates where it s warm and hot and very sunny, some shading of the fruit is usually benefical
The grape grower may ensure the grapes are covered with one thin layer leaves, so
that the bunches receive dappled (gevlekte) sunshine
Sunshine in late spring/ early summer is also associated with succesful fruit set and the exposure of compound buds promotes:
bud fruitfulness in next year’s growing season
Natural factors that effect temperature and sunlight:
1) latitude
2) Altitude
3) slopes and aspect
4) Proximity to water
5) Winds
6) characteristics of the soil
7) mist, fog and clouds
Latitude:
a) regions at lower latitudes (nearer the equator eg Mendoza, SA, New South Wales) will recieve more solar radiation per annum than regions at higher latitudes (Nearer te Poles Northern france and germany)
b) solar radiation is absorbed (held by water droplets, dust and ozone)
it travels through the earths atmosphere, this decrease the intensity
c) the curvature of the earth means that nearer the poles solar radiation must travel through a larger section of atmosphere
- – it also means the radiation hits the earth at a low angle and spread over a larger area
- —- by contrast at the equator the radiation travels through a smaller section of atmosphere ad hits the earths surface at a larger angle (nearer perpendicular (loodrecht)
very broadly speaking: grape grown at lower latitudes can have higher levels of sugar, ____ levels of acidity, _____ aromas and in black grapes _____ but _____ tannins and more ______ intensity than those at higher latitudes.
1) lower
2) riper
3) more
4) riper
5) Colour
The number of hours of solar radiation through different times in the year is also determined by latitude:
a) low latitude regions receive similar daylight hours (and hence (dus) heat and sunlight) throughout all seasons of the year
b) Higher latitude regions have longer daylight hours in the summer and shorter daylight hours in the winter
- – this permits more light= more photosynthesis
- – given the cooler temp in these locations, this can be useful in helping the vine to produce enough sugar for ripening grapes
Its generally said grapes for wine production can grow between:
30°and 50° latitude on each side of the equator
there are exceptions to this:
a) regions nearer the equator are usually too hot during the day
- - vines transpire to regulate their temp
- - if water is not available: water stress
- - grapes can suffer from sunburn
b) regions near the poles are simply not warm enough during the growing season (despite long daylight hours) for enough sugar to accumulate
altitude:
1) temp falls by approximately 0.6°c (1.1f) over every 100 m increase in altitude
2) high altitudes are good for regions that are normaly too hot
- - Salta: vineyards at up to approximately 3000 m above sea level
- - grapes may struggle to ripen suff every year
3) vineyards in higher latitude are at lower altitude, (burgundy loire) otherwise temp too low for suff ripening
4) sunshine is more intens at higher altitude because the solar radiation travels through less atmosphere before it reaches these sites
- - ultraviolet (radiation with a lower wavelength than visible sunlight) is also greater at higher altitudes.
- – both of these factors are thought to promote anthocyanin and tannin synthesis
High altitude sites often have a high diurnal range
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