Effects of zeolite application and irrigation on berry sunburn damage and vine performances in ‘Sangiovese’ (Vitis vinifera L.)

In the face of escalating climate change, the surge in heatwaves and prolonged droughts has become a pressing concern, significantly impacting grape maturation. Additionally, the combination of prolonged high-light intensities, high temperature, and UV radiation might result in a damage called berry sunburn. Recognizing the gravity of these emerging challenges, this study delves into the exploration of diverse mitigation strategies aimed at reducing berry sunburn incidence, preserving yield, and enhancing grape composition at harvest. Irrigation during berry ripening has recently been reconsidered as a way to cope with climate change. Similarly, foliar mineral treatments with mineral based compounds, such as zeolites, have aroused interest as a sustainable approach to cope with high temperature stress in vineyards. Thus, late irrigation and zeolite application were tested in 2021 and 2022 on 'Sangiovese' vines, cultivated near Bologna and trained to VSP spur-pruned cordon. Treatments were arranged in a strip-plot design and the main factors were: cluster exposure/ management (leaf removal of the basal leaves at veraison, leaf removal coupled with zeolite treatment, and no leaf removal) and irrigation (irrigation from berry softening to the end of August vs. no irrigation). At harvest, the incidence and severity of berry necrosis and berry shrivel damages were recorded. Yield parameters were measured and grape composition analyzed, while frozen berries were used for anthocyanin analysis with HPLC. Both years were characterized by harsh summers (max Tair >40°C). In this context, berries sheltered by foliage exhibited no signs of distress, while exposed clusters benefited significantly from both zeolite application and irrigation, effectively mitigating sunburn and the consequent decline in production. Irrigation however, resulted in a decrease in both berry soluble solids content and anthocyanins and therefore, a careful calibration of the management techniques to reduce the adverse impact of climate change on the berries will be needed. © 2025 International Society for Horticultural Science