Technical Yearbook 2023

regular intervals after treatment, leaves were sampled, on which proline concentration was determined. After sampling, the leaves were cleaned with distilled water to remove any exogenous proline deposits so that only endogenous proline was measured (i.e., contained in leaf tissues). One hour after treatment, no significant differences between the treatments were observed. Starting from three days after treatment, the percentage variation of proline compared to pre-treatment levels gradually and steadily increased from +68% to +170% at 14 days from treatment, while untreated plants in the same period recorded a proline increase of 50%. This means that preventive treatment with LalVigne ProHydro™ prepares the plant for water stress and osmotic imbalances, with a priming effect that leads to earlier, more abundant proline biosynthesis. In addition to its osmolytic function, proline acts as a free radical scavenger, preventing permanent tissue damage caused by oxidising chemical species the vine produces when under stress. From a practical point of view, this translates into better use of the water resource for photochemical processes and thermoregulation, favouring preservation of low foliage temperature and more effective prevention of excess energy that causes yellowing and foliar abscission. Experimental trial set up Perugia University, in collaboration with Università Cattolica del Sacro Cuore (Piacenza), evaluated the use of LalVigne ProHydro™ on the physiological and production functions of seven-year-old vines ( cv. Sangiovese, clone

VCR30) grown in pots and artificially subjected to water stress conditions in a period of high temperatures.

PHOTO 2. Potted vines subjected to water stress. Left, untreated vines with evident chlorosis caused by water stress; right, vines treated when ripe with LalVigne ProHydro™, where no damage from water stress is evident.

FIGURE 3. Physiological parameters recorded in plants treated and not treated with LalVigne ProHydro™, indicated by the arrows at a dose of 1 kg/ha: plants always irrigated (A, C) and subjected to a period of pre-veraison water stress (B, D). A and B: photosynthesis and maximum air temperature; C and D: water use efficiency (WUE) calculated as the ratio between photosynthesis (Pn) and stomatal conductance (gs). *: indicates significant differences between control and treatment.

9

TECHNICAL YEARBOOK 2023