Home Industry News Featured Post Monitoring Stem Water Potential in Grapevine (Case Study on Cabernet)

Monitoring Stem Water Potential in Grapevine (Case Study on Cabernet)

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Plant water status is a crucial aspect of quality grapevine growing. Precisely managing grapevine’s water stress during different stages in the growing season will result in grape optimal quality and quantity.

Water stress level and timing determine grape’s aroma profile. It can also affect the amount of polyphenols in the grape skin and determine the wine’s aging potential. Lastly, it can affect the yield and farmer’s income.

For years Stem Water Potential (SWP) was the most common and precise parameter for evaluating the water stress level but measuring SWP involved a labor-intensive manual instrument. Moreover, because of the manual measurement, it’s usually only done once a week and provides a single weekly SWP value on which the farmer bases its irrigation strategy. Some farmers use soil sensors to evaluate water soil tension. But, this parameter reflects a specific area of the vineyard, and most importantly, it is less sensitive to water stress – it will display water stress slower and less efficiently.

Saturas StemsenseTM sensor measures daily SWP continuously, automatically, and precisely. The current development from Saturas is a small 6 mm sensor, adapted for grapevine measuring.

The 6 mm StemsensTM sensors were installed as part of a field trial in Israel’s Golan Heights region.

The layout

8 Saturas 6 mm StemsenseTM sensors were installed in a premium Cabernet Sauvignon vineyard in the Golan Heights region.  The vineyard is about 700 m above sea level on volcanic basaltic clay soil with high greval content with a medium water holding capacity.

The StemsenseTM sensors were installed adjacent to soil sensors that measure soil water tension in 3 depths (40, 80, 120 cm). The StemsenseTM sensors measured daily mid-day SWP value. SWP was measured usually once a week with a manual pressure chamber.

Results and conclusions

Saturas 6mm StemsenseTM sensors showed an excellent response to irrigation and changes in evapotranspiration (Figure 1). Saturas 6mm StemsenseTM sensors were correlated to the SWP values measured with the manual pressure chamber during the trial period. Saturas sensors showed continuous values throughout the trial period, thus enabling daily monitoring of the vine’s water stress and better irrigation scheduling decisions.

The pressure chamber measurements, done by the farmer, were scheduled according to the technician’s availability. It is quite apparent that these measurement’s timing is crucial for irrigation scheduling decisions, and, as seen in figure 1, irrigating following the pressure chamber weekly measurements isn’t good enough.

The soil sensors showed similar soil water tension values in the 4-5 days before irrigation, while the StemsenseTM sensors displayed a wide range of values in that period (Figure 2). For example, StemsensTM sensors showed an increase of values from 14 bars to 20 bars, which means from no stress to high stress. At the same time, soil sensors hardly show any increase.

Figure 1 – Seasonal values of Saturas 6mm InVineTM monitor Mid-Day SWP values, pressure chamber Mid-Day SWP values, daily ET0, irrigation volumes.
Figure 2 – Seasonal values of Saturas 6mm InVineTM monitor Mid-Day SWP values and soil water tension in 40 cm depth and 80 cm depth.

From the results seen in this case study, we can conclude that:

  • Saturas 6mm StemsensTM sensors were the only measuring tool to display precise and continuous daily values – using the StemsensTM sensors, the farmer can react immediately to climatic changes and water stress.
  • Saturas StemsensTM sensors are the only measuring tool that can be used to irrigate according to the precise SWP threshold, a crucial requirement for moderated stress management irrigation strategies used in vineyards to obtain the best grape quality.
  • Plant water status depends not only on soil water availability but the plant’s vegetative state and climatic parameters play a dramatic role – StemsensTM sensors accurately reflect the plant water status directly, taking into consideration all these important parameters.

For more information visit Saturas Ag.

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