Evaluation of a fruit-zone cooling system to face multiple summer stress in ‘Sangiovese’ grape

In the Mediterranean basin, vines are more often exposed to severe heatwaves combined with scarce water availability during ripening, which might have drastic consequences on vine's physiological status. Moreover, this condition is usually worsened by high solar radiation, leading to a depletion of production due to sunburn damage associated with a decline in grape composition. For this reason, the aim of the study was to develop a fruit-zone cooling system to reduce grape sunburn damage and improve canopy microclimate conditions. The system is composed of both a network of proximal sensors able to acquire the microclimate data within the vineyard and an actuator that triggers the nebulizers when the threshold of 35°C is exceeded. The system was evaluated during the 2022 season in Bologna (Italy) on potted ‘Sangiovese’ vines and in a ‘Sangiovese’ vineyard. In both tests, the application of nebulized water in the cluster zone (FOG) was able to reduce the berry temperatures compared to the untreated control (C). In addition, the cooling effect benefited the entire canopy which showed an increase in gas exchange. Furthermore, the vines subjected to nebulized water were shown to be more productive than the control vines without affecting any technological maturity and berry colour attributes. In conclusion, the cooling system of the fruiting area seemed to be an excellent device for reducing the negative effect of multiple summer stresses on the grapes in terms of sunburn damage and grape composition.