Author
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Shellie, Krista |
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Submitted to: National Viticulture Research Conference
Publication Type: Proceedings Publication Acceptance Date: 6/1/2007 Publication Date: 7/2/2007 Citation: Shellie, K. Wine grape response to foliar kaolin particle film under differential deficit irrigation. National Viticulture Research Conference Proceedings. p 83. Interpretive Summary: Technical Abstract: Deficit irrigation improves grape quality for wine production. However, under arid production regions with high solar radiation, water stress may render the vine more susceptible to solar injury and inhibit fruit ripening. This is the first year of a multiyear study to examine the impact of kaolin-particle film on fruit and leaf physiology for the cultivar Merlot under differential levels of deficit irrigation. An irrigation field trial established in 2002 at a commercial vineyard near Nampa, ID was used to impose a split plot of kaolin or non kaolin vines in main plots that were provided water at differential amounts of their estimated evapotranspiration needs. Vine water status was monitored weekly by measuring midday leaf water potential 6 d after the last irrigation. Diurnal stomatal conductance , leaf surface temperature and midday leaf water potential were measured pre and postveraison. Yield per vine, average cluster weight, berry weight and must composition were determined at harvest. Results from year one suggest that vine water status had a greater impact on leaf water potential, gas exchange and fruit composition than kaolin particle film application. Vines irrigated with 100% of estimated evapotranspiration had the highest leaf water potential and stomatal conductance, and differences among irrigation treatments were larger than between kaolin and non kaolin leaves. Neither irrigation nor kaolin application impacted harvest levels of brix (25%) or titrable acidity (4.3 g/l), though fruit from kaolin treated vines had lower pH (3.8 versus 3.9). There was no observable difference in incidence of fruit defects in any irrigation treatment or with kaolin application. Under the high evaporative demand and high solar radiation of this trial site, vine water status impacted leaf surface temperature more than particle film application, and the leaf-air vapor pressure difference of kaolin treated leaves was not of sufficient magnitude to elicit a measurable response in stomatal conductance. |
