Combined effect of basalt dust foliar distribution and water availability on leaf morpho-physiological traits and grape quality in Falanghina

Climate change in the internal areas of the Mediterranean region is causing a decrease in the frequency of rains and an increase in temperatures, leading to dryer and warmer seasons. These conditions, which will become more and more intense in the coming decades, are already affecting viticulture (e.g. photoinhibition, leaf and berry sunburn) influencing the growth and physiology of vines together with the yield and quality of grapes. The sustainability of vine cultivation in these areas is increasingly at risk, thus, the definition of sustainable cultivation techniques is pivotal to stabilize production and maintain high quality standards of the grapes.

The aim of this work is to evaluate the effects of the application of basalt dust on the leaf surface of Vitis vinifera L. subsp. vinifera ‘Falanghina’ grapevine, grown under two different water availability levels over two years characterized by different climatic conditions. The experiment was conducted between 2021 and 2022 in a commercial vineyard of La Guardiense farm at Guardia Sanframondi (Benevento, southern Italy), in the Sannio wine district. The treatment blocks set, localized after geo-physical analysis of the soil, were the following: DI (distribution of basalt dusts and irrigated; Dust-Irrigated), DR (distribution of basalt dusts and rainfed; Dust-Rainfed), NDI (without basalt dusts and irrigated; No Dust-Irrigated), and NDR (without basalt dusts and rainfed; No Dust-Rainfed). The basalt dusts were distributed during the productive-vegetative cycle of the vine (from April to September) and the irrigation was managed according to weather conditions and soil water availability. During the two years of trials, the vegetative growth was monitored through biometric measures, the eco-physiological characteristics through leaf gas-exchanges, chlorophyll “a” fluorescence emission and leaf water potential, during the four main phenological phases: flowering, fruit set, veraison and maturation. Eco-physiological traits were also linked to leaf functional anatomical traits (e. g. lamina thickness, localization of phenolics, stomatal size and frequency) to detect mechanisms for acclimation. After the measurement of fertility, the grapes from each plot were harvested and micro-vinified. The musts and wines were chemically characterized to understand the oenological potential of each one. The analysis of the data from the two seasons 2021 and 2022 allowed us to unravel the effect of inter-annual climatic variability on the potential for photoprotection of the dust distribution. Gained information is useful to evaluate whether the use of basalt dust can be considered a tool for mitigating water stress and rationalizing irrigation protocols.