Grapevine, berry and soil Indicators to manage minimal irrigation strategy in semi-arid conditions: example of Grenache noir (Vitis vinifera L.)

Abstract

Context and purpose of the study. Climate change in many Mediterranean wine-growing regions is resulting in lower rainfall and higher reference evapotranspiration, generally leading to reduced water availability for vines. This necessitates rethinking cultural practices, including the use of irrigation. This article aims to present the key soil-climate and vegetative-berry development variables that should be considered for effective minimal irrigation management, ensuring yield consistency and acceptable berry quality that meets market demand.

Material and methods. The experiment was conducted over two successive years (2022–2023) on cv. Grenache N. (Vitis vinifera L.) grafted onto 110R in a commercial vineyard located in the Pyrénées-Orientales wine region, in the south of France. A minimal irrigation treatment (50 mm/year), supplementing the limited rainfall (less than 250 mm/year), was compared to a rainfed treatment.

Results. Among the key findings of this study, the relationship between soil water content, measured using a capacitive probe, and vine water status, assessed through predawn leaf water potential, differed between drip-irrigated and rainfed treatments. This highlights the practical need, given the current stage of knowledge, for proper parameterization of the curve linking these two variables when implementing drip irrigation.

In addition to soil and/or plant water assessments, tracking berry volume (or fresh mass) and primary metabolites, including sugars and malic acid, from véraison onwards, appeared essential to identify potential plant water and carbon imbalances. This information is crucial for adjusting both the timing and amount of minimal irrigation during ripening.

A methodology incorporating a reduced number of measurements of soil and/or plant water status and berry development variables at key phenological stages is proposed to help winegrowers achieve predefined yield and wine quality targets while minimizing their water footprint.