Michael Santiago, Winston L. Black, Siyu Zhu, Erik J. Huber, Adriana C. Mulero, Andrew M. Bryan, Alan N. Lakso, and Abraham D. Stroock*
*Cornell University, 260 Olin Hall, Cornell University, Ithaca, NY 14853 (abe.stroock@cornell.edu)

Stem water potential is the best measure of a grapevine’s hydration relative to growth, grape yield, and quality; it provides vital information on plant health and helps decide schedules for irrigation and harvesting. Unfortunately, direct measurement of water potential in plant tissue is only possible using labor-intensive, destructive methods such as the pressure bomb and stem psychrometer, and indirect measurements of water potential through the soil using tensiometers are unreliable for woody plants.

We are bringing tensiometers from the soil into the stem. Using microchip technology, we have developed a miniature tensiometer (microtensiometer) small enough to be embedded in the vine stem, where it can measure stem water potential directly from the xylem, in real time, down to potentials below -100 bars without emptying. This sensor has been tested successfully in a laboratory setting and is now being tested in live grapevines. Current development challenges include long-term corrosion protection against humidity and UV, mechanical encapsulation, and embedding/sealing protocols. Our goal is to develop a “set and forget” sensor that can provide continuous water potential measurements for multiple seasons without maintenance, allowing vineyards direct control over water status to “dial in” their vintage, conserve irrigation water, and improve grape yield and quality.

Funding Support: NIFA, USDA, NSF, Sloan foundation