Temperature, humidity, wind, and sunlight are the four major variables of microclimate, the physical environment around the vine and across the vineyard.  Historically, scientists studied the effects of temperature on plants in controlled environment chambers or greenhouses, completing experiments that provided us with some of our fundamental knowledge about plants.  Outside, in the vineyard, we can extend our understanding of grapevine biology in the real world environment where the microclimate represents the complex interaction of multiple factors (temperature, wind, humidity, sunlight) that change continuously.
The temperature of dormant buds is controlled for several weeks during the spring.
In one approach, we allow wind, humidity, and sunlight to vary according to Mother Nature, but we control the temperature of part of the vine using the device pictured above. This heater-cooler device was designed and built to deliver hot and cold air to different parts of the vine so that we can determine specific effect of temperature on vine biology.  Thus we keep the vine in a situation as close to the real world as possible while studying one aspect of the microclimate.  Doing so in the context of fruit ripening has allowed us to suggest alternate farming practices for growers who find too much 'sunburn' or browning of the ripening fruit in their vineyards. Click here for related articles.
The temperature of this grape cluster, seen here before flowering in June, is kept below normal by cold air delivery from tube at right.
Scientist: Julie Tarara