Vineyard Canopy Management
Vineyard Canopy Microclimate
The vine’s microclimate comprises a number of factors including solar radiation, temperature, wind speed, humidity, and evaporation. When the canopy microclimate is altered by canopy management techniques, it is not only sunlight levels that change but temperature, humidity, wind speed, and evaporation too. Therefore, variation in canopy microclimate has implications for grapevine yield, fruit composition and quality, and disease incidence.
A large canopy surface area well exposed to sunlight is desirable for biomass production and yield potential. In open canopies the majority of leaves and a high percentage of fruit clusters are exposed, whereas in denser canopies a large percentage of leaves and most clusters are in the shade of the exterior leaf layer.
Temperature can have a significant effect on shoot growth and fruit quality. Typically, as temperatures increase, the rate of shoot growth increases. However, high temperatures (> 90°F or 35°C) can decrease shoot growth by shutting down photosynthesis, leading to reduced sugar accumulation and reserves and rapid acid degradation (Spayd et al., 2002).
Wind Speed, Humidity, and Evaporation
In an open canopy the humidity remains at or near the ambient air humidity, whereas in a dense canopy humidity can increase by as much as 10 percent as leaves transpire. Air movement within dense vine canopies is reduced compared to canopies that are more open. In very dense canopies wind velocity can be reduced to only 10 to 20 percent of that out-side the canopy (Allen, 2011).
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