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United States Department of Agriculture

Agricultural Research Service

Research Project: VINEYARD MANAGEMENT PRACTICES AND THE QUALITY OF GRAPES AND GRAPE PRODUCTS IN THE PACIFIC NORTHWEST Title: Is timing the key to good fruit phenolics?: year 3

Authors
item Tarara, Julie
item Lee, Jungmin
item Skinkis, Patricia -

Submitted to: Northwest Center for Small Fruit Research Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 28, 2013
Publication Date: November 28, 2013
Citation: Tarara, J.M., Lee, J., Skinkis, P.A. 2013. Is timing the key to good fruit phenolics?: year 3. Northwest Center for Small Fruit Research Proceedings. Proceedings of Northwest Center for Small Fruits Research.

Interpretive Summary: This is a final report (year 3) for a NCSFR funded proposal on our findings to better understand the relationship between canopy management (via vineyard floor manipulation) and berry quality.

Technical Abstract: Research was conducted in a commercial vineyard in Oregon. The vineyard soil was managed in three ways to alter vine growth, including growing grass between the rows of vines, soil tilled to remain bare, and a combination of alternating tilled and grassed areas between vine rows. Grapevine yield was deliberately reduced or was left at its natural level. For each combination of fruit level and vineyard floor management, we measured the total area of leaves produced by the plant, how much sunlight was absorbed by the leaves, how much water was in the soil, and yield. Most importantly, we measured how much nitrogen, a plant fertilizer, was present in each part of the plant: the shoots, the leaves, and the fruit. More extensive measurements of fruit chemistry were conducted at harvest to assess the quality of the fruit for winemaking. Grass planted between rows of grapevines effectively reduced excessive growth of the vines by competing with the plants for nitrogen rather than for water, as had been previously thought. The effect on yield of the grass and bare soil was different in each year of the study, which is often the case in perennial crops. It is more difficult to predict yield based on the amount of nitrogen in a perennial compared with annual crops because in perennial crops, next year's fruit begins to form during the present year. Whether there was grass or bare soil between the rows of grapevines had a greater effect on the total amount of leaves produced by the vines than it did on yield. Fruit quality was not significantly affected by changing the level of fruit on the vine.

Last Modified: 12/18/2014
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