HYBRID EVENT: You can participate in person at Rome, Italy or Virtually from your home or work.
AGRI 2023

Pete W Jacoby

Pete W Jacoby, Speaker at Agriculture Conferences
Washington State University, United States
Title : Direct rootzone irrigation for enhancing drought resilience of winegrape vineyards


A novel system for delivering subsurface drip irrigation has been developed, improved, and verified through peer-reviewed research publications over the past eight years. Water savings and improved grape quality have been documented from in-field experiments conducted under hot dry growing conditions within commercial winegrape vineyards in Washington State, USA.  Presenter will summarize findings from currently published data including enhanced crop water productivity, effect of water volume on yield and quality of grapes, impacts on rates of deficit irrigation on vine physiological activity, impacts of surface and subsurface irrigation on vine root architecture, use of soil water sensors to schedule irrigation intervals and water volume per application, and current research on maintaining constant levels of vine stress with automated irrigation driven by sensors measuring soil water content and matric potential. Major research findings to date include: 1) Direct Root Zone (DRZ) subsurface drip irrigation saved 23-34% of the water used for surface drip (SD) irrigation; 2) red wine grapes under DRZ had less acidity, higher Brix, higher tannin, and higher anthocyanins than grapes irrigated by SD; 3) white wine grapes had increased yeast assimilable nitrogen (YAN) under DRZ versus SD; 4) DRZ vines had higher physiological activity during mid-day measurements of photosynthetic activity and atmospheric carbon exchange than SD irrigated vines; 5) DRZ vines had fewer roots in the upper soil profile than SD vines and DRZ vine developed deeper roots than SD vines, as determined by mini-rhizotron digital imagery; and 6) UAV remote sensing was shown to be highly correlated with xylem pressure potential.


Dr. Jacoby holds a BS from Texas A&M University and MS and Ph.D. degrees from the University of Wyoming. During his early career, he served as Extension specialist and Research scientist at the University of Arizona and Texas A&M Agri-Life. He served in administrative positions at the University of Nebraska and Washington State University before returning to a research position at WSU. He developed a method of applying subsurface irrigation known as Direct Root Zone (DRZ), and research associated with this method to conserve water in winegrape vineyards has been published in high impact international scientific journals.                                          

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