Phenological stage dependency of Cabernet Sauvignon and Grenache response to water and nutrient limitation 

Abstract

As the frequency and intensity of drought events increase, understanding the mechanisms of plant resilience to water deficit is crucial. To maintain an appropriate plant yield, a common practice is the application of high amounts of fertilizers with negative environmental impacts. The single and combined effect of water deficit and nutrient availability, namely nitrogen (N) and potassium (K), in Vitis Vinifera L. cv. Cabernet Sauvignon and Grenache was evaluated. Two-year-old grapevine plants grafted on SO4 rootstock were transferred in pots under semi-environmental conditions. During the growing season, plants were either maintained well-watered (100% ETc) or subjected to a controlled water deficit irrigation (33% ETc). Moreover, different N and K fertilization doses were applied: 100%N+100%K; 100%N+30%K; 30%N+100%K; and 30%N+30%K. Several morpho-physiological parameters were periodically evaluated, including plant growth rate, midday stem water potential, and gas exchange parameters. In addition, multi‑elemental analysis was conducted by collecting leaves at flowering, veraison, and maturity stage.

Early-season results showed significant effect of irrigation on stomatal conductance and transpiration rate, especially in Grenache. Multi-elemental data at flowering stage showed that plants mainly separated in response to irrigation treatment. Conversely, the physiological response and the nutrient composition at the maturity stage was strongly influenced by N fertilization.

The obtained results will improve the comprehension of the mechanisms involved in the signaling network of the interplay among water and nutrient acquisition.

PRIN 2022 PNRR: P20222XJKY; Agritech (PNRR MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4 – D.D. 1032 17/06/ 2022, CN00000022); PSD Artificial Intelligence 2020-25, University of Udine.