AN AUTOMATIC CANOPY COOLING SYSTEM TO COPE WITH THE THERMAL-RADIATIVE STRESSES IN THE PIGNOLETTO WHITE GRAPE
In recent years characterized by hot dry summers, the implementation of innovative irrigation tools in the vineyard represents a crucial challenge to ensure optimal production and to avoid excess of water consumption. It is known that the grapevine reacts to multiple stresses – i.e., high temperatures and wa- ter shortage – through adaptive mechanisms that are detrimental to the yield. Furthermore, this condi- tion is usually aggravated by high solar radiation, which could negatively affect the phenolic composi- tion of the grapes. Therefore, a cooling system has been developed aiming to reduce bunches’ sunburn damage. The system is composed of both a network of proximal sensors able to acquire the microclimatic data within the vineyard and an actuator that triggers the nebulizers when the air temperature threshold of 35 °C is exceeded. The system was evaluated at the experimental vineyard of University of Bologna during the 2022 season on Pignoletto, an Italian white grape cultivar. Three treatments were evaluated: non-defoliated control (C), vines subjected to defoliation of the basal leaves (DI) and vines subject to the same defoliation and sprayed with nebulized water (FOG) in order to verify the effects on yield attri- butes, berry necrosis and secondary metabolites such as flavonols, responsible for white wine browning. The application of nebulized water in the cluster zone was able to reduce the temperatures of the berries compared to C and DI. Furthermore, the vines subjected to nebulized water showed to be more produc- tive than the C and DI vines without affecting any technological maturity parameters. In conclusion, the cooling system of the fruiting area seems to be an excellent device for reducing the negative effect of multiple summer stresses on grapes with regards in sunburn damage and grape composition.
Issue: OENO Macrowine 2023
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Climate change, Precision irrigation, Sunburn damage, Phenolic maturity