New research reviews plant-based methods for monitoring vine water status in sustainable vineyard management

A recent review published by the International Viticulture and Enology Society (IVES) examines the latest scientific findings on plant-based methods for assessing vine water status, a key factor in sustainable vineyard management. The study, authored by Markus Rienth, Cécile Laurent, and Thibaut Scholasch, highlights the importance of accurate water status assessment as climate change and water scarcity increasingly challenge viticulture worldwide.

Vine water status directly influences decisions on irrigation and other cultural practices. The review focuses on direct, plant-based measurement techniques, comparing their effectiveness and limitations in real-world vineyard conditions, especially during droughts or periods of high vapor pressure deficit (VPD).

Visual observation remains one of the oldest methods for detecting vine water stress. Early signs include loss of turgor in tendrils and reduced shoot growth, which can be seen at the shoot apex. However, this method is limited to periods of active growth and is highly subjective. Operator experience and environmental factors such as nitrogen deficiency or high VPD can lead to misinterpretation. New tools like smartphone applications have been developed to standardize visual assessments, but reproducibility remains a concern.

Water potential measurement is another widely used technique. It involves measuring the tension under which water moves through the vine’s xylem using a pressure bomb. Measurements can be taken at the stem (SWP) or leaf (LWP) level. LWP readings at midday provide a snapshot of maximum daily stress but are sensitive to rapid environmental changes. Predawn measurements are intended to reflect equilibrium with soil moisture but recent research shows that nighttime transpiration and VPD can still influence results. This means predawn LWP may not always accurately represent available soil moisture.

A key limitation of water potential measurements is their tendency to overestimate vine stress during drought or high VPD events. As water tension increases from root to leaf, air bubbles can form in the xylem—a process called cavitation—which disconnects leaves from the main water flow. In these cases, leaf measurements may not reflect actual vine status.

Carbon isotope discrimination offers a different approach by analyzing the ratio of stable carbon isotopes (13C/12C) in plant tissues. This ratio changes as vines experience water or nitrogen deficits, providing an integrated record of stress over time. However, this method is retrospective and not suitable for day-to-day irrigation decisions since it only provides information after the growing season.

Sap flow measurement tracks the movement of water through the vine’s xylem from roots to leaves. Two main methods exist: thermal dissipation probes and stem heat balance sleeves. Thermal dissipation probes use heated needles inserted into the vine but are prone to errors due to tissue variability and are not widely used commercially. The stem heat balance method uses a non-intrusive sleeve that wraps around the stem, providing more reliable data by accounting for variations in sap flow across the stem.

The review emphasizes that practical irrigation scheduling requires real-time, continuous data that represents conditions across large vineyard blocks. Most plant-based methods are labor-intensive and only sample a few vines at a time, making it difficult to capture spatial variability within vineyards. Continuous monitoring systems help avoid missing critical stress events but require permanent installations.

Each method has its own operational challenges. Visual symptoms appear too late for timely irrigation adjustments. Water potential readings can be skewed by cavitation during high VPD periods. Carbon isotope analysis is useful for evaluating past management strategies but not for immediate decisions. Sap flow measurements support precise irrigation scheduling but require careful installation and maintenance.

The authors note that plant-based methods do not directly measure soil moisture or atmospheric conditions like VPD; instead, they reflect how vines respond to these factors at the time of measurement. For optimal irrigation management, plant-based data should be interpreted alongside soil moisture readings and weather data—especially VPD—to ensure efficient water use.

The study concludes that while no single method provides a complete picture, combining plant-based measurements with environmental monitoring offers the best approach for managing vineyard irrigation under changing climate conditions. The findings underscore the need for ongoing research and technological development to support sustainable viticulture practices worldwide.