Deep Subsurface Irrigation in Concord VineyardsZara York4, Pete Jacoby1, Troy Peters2, Sindhuja Sankaran3, Lav

Khot3, Jeremy Thompson4

1Professor, Crop & Soil Science, 2Associate Professor and 3Assistant Professors, Biological Systems Engineering,4Student Research Interns - CAHNRS

Results

Acknowledgements

Objectives

This activity was initiated with an Internal Competitive grant to address Emerging Research Issues and issued from the CAHNRS Office of Research. Additional support was provided through a competitive grant issued by the WA State Concord Grape Research Council. The authors also wish to thank Clint Graf, Orchard/Vineyard Manager and the Farm Support Team at WSU Prosser-IAREC for providing timely and exceptional local support during this project, and to Dr. Markus Keller, Chateau Ste. Michelle Distinguished Professor of Viticulture at WSU, for his knowledgeable advice and support regarding all aspects of viticulture and plant physiology.

Methods

Preliminary data are presented from early veraison, and will be statistically analyzed along with future data. The vines in treatments 2-4 exhibited increased water stress than the control (standard drip, SD), while treatment 1 had less water stress than the SD. Treatments 1 and 4 of the subsurface drip (SDD) had similar water stress as the standard drip SD control. All treatments for the SDD irrigation showed markedly higher average cluster weights. In addition, all SDD treatments had a higher number of average berries per cluster. The average individual berry weight was higher than the SD for the SDD treatments 2 and 4, while SDD treatments 1 and 3 were lower than the SD. Additional samples will be collected before harvest.

Research conducted at the Roza Research Farm near Prosser, WA. Experimental treatments contrast standard surface drip irrigation with subsurface drip irrigation applied through hard PVC delivery tubes installed at one foot increments at depths of 1’ to 4’ to apply water into the root zone. The tubes have an emitter that is attached to the overhead driplines. Plant production is estimated from grape cluster samples collected at the first signs of veraison, mid-veraison, and at the time of harvest. Each of the five treatments will have three or more “average” clusters removed for sampling. The samples collected will then be used to analyse the weight of an average cluster, average number of grapes per cluster, and the average grape weight. These will be used to compare with the controls, as well as comparing to grower’s standards for selling the grapes. Vine stress is being measured through pressure bomb readings to determine mid-day stem xylem pressure potential.

● Contrast deep subsurface irrigation and surface drip irrigation applied at reduced amounts of water application.

● Monitor water stress and its impact on fruit production. ● Estimate the most efficient zone for water application.

On the Left: Grape leaf was placed within two bags and an aluminum packet to block sunlight.Top Right: Leaf was cut from vine, removed from foil and outer bag, and placed in pressure bomb.Bottom Right: Water Stress is the pressure required to force liquid from the leaf out through the stem.

Multi-spectral aerial image of treatment area during mid-summer.