D1 the growing environment - water Flashcards
Water
The vine needs 500mm of rainfall per year in cool climate and 750mm per year in warm climate.
The vine needs right amount of water for photosynthesis, transpiration and for nutrients uptake.
The effect of water
The effect of the vine:
The vine regulate its water needs trough the transpiration (water from the roots, out from the stomata).
This allows co2 in for photosynthesis (oxygen and glucose are produced).
The timing of water :
Spring; Plentiful of water support shoots and leaves growth.
Veraison: mild water stress is desirable.
At ripening: too much water cause dilution of sugar in grapes. By comparison, too little water lead to early shrivel of grapes.
Hazards, rainfall can
- uneven flowering, lowering yield.
- Increase humidity, leading to fungal disease. By comparison, low humidity increase evapotranspiration, therefore promoting water stress.
- hail can cause damage, lower yield and quality.
Benefits
it can mitigate the climate. Providing cooling breezes during the day and warm air during the night (to mitigate the winter freezes and spring frosts)
Natural factor that affect water availability - Rainfall and soil
The amount and the timing of rainfall is moderated by the drainage-capacity and the water-holding capacity of the soil.
Which depends on the soil structure and texture.
(sand and gravel are free draining, clay retain water, releasing it slowly).
Slopes has greater surface run-off.
Means less penetration of water (advantageous with high rainfall)
However, cause erosion of the soil and leaching of nutrients (also because is very thin).
Water-logged soil may suffocate the roots, slowing their growth.
Natural factor that affect water availability - Evapotranspiration
Evapotranspiration rate is the rate at which water is no longer available.
(transpiration of the vine combine with evaporation of water from the soil)
A higher rate means more water is needed for the vine.
