Use of a portable vis / NIR device to monitor the accumulation of anthocyanins during ripening in berries of Sangiovese cv (Vitis vinifera L) under heatwave conditions

The rapid progress of precision techniques in viticulture and the goal of quickly establishing the optimal harvest time, have led to the development of increasingly efficient portable vis / NIR devices. These tools can reduce the sampling time and the costs of chemical analyses usually applied during ripening to monitor the composition of the berries and establish the right harvest time. Nowadays, evaluation of polyphenols and anthocyanins in red grapes is rarely performed, since it involves costly and time-consuming procedures. The literature has also highlighted that in recent years - characterized by strong heatwaves - the accumulation of anthocyanins in grapes may be strongly suppressed. In this context, smart/easy techniques to both verify the evolution of anthocyanin concentrations and to reduce the negative impact of high or excessive temperatures on the grapes are strongly pursued objectives. Starting from these assumptions, in the two years 2019-2020, at the University of Bologna, a non-invasive and portable vis / NIR device (berry adapted DA-meter) was evaluated to monitor the accumulation of anthocyanins on cv. Sangiovese in control grapes (C) and subjected to kaolin treatment (K). The kaolin applications were performed to lower the temperature of the berries in order to affect the anthocyanin concentration to test the effectiveness of DA-meter. The mineral was sprayed twice around the veraison on the entire canopy at a 3% concentration. The results showed that the application of the kaolin was able to reduce the berry temperatures in both years of the trial as compared to the C, increasing anthocyanin on grapes detected by both chemical and non-destructive approaches. In conclusion, the berry adapted DA-meter appears to be an excellent and smart device for quick in-field measurements.