A Heat-Shock Generator for Dormancy Release of Grapevines in the Vineyard

In warm-winter regions, where early ripening of table grapes is enabled by the climate, prolonged dormancy is a major delaying obstacle to early-season marketing. Successful production in these regions depends on chemically or physically overcoming the dormancy cycle to compensate for lack of natural chilling. It was previously shown that heat shock from hot air at 150°C induces dormancy release of detached grapevine buds under a controlled environment. In the present study, a heat-shock generator (HSG) for enhancement of dormancy release of whole vines was developed and tested under field conditions. The HSG heats a partially-enclosed volume of air to a required temperature and conveys it through the vines at a speed that results in the desired exposure duration. Heat shocks of 150°C for 15 and 30 s applied in situ to dormant cv. Muscat of Alexandria vines induced earlier dormancy release and significantly greater yield (156%) relative to the control. A longer heat shock of 90 s negatively affected the dormancy release. The HSG is similar to other common agricultural practices in operational simplicity, and its cost and environmental benefits make it a viable alternative to chemical application.