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United States Department of Agriculture

Agricultural Research Service


Location: Commodity Protection and Quality Research

2012 Annual Report

1a. Objectives (from AD-416):
Improve the quality and storage life of table grapes by the application of sprays directed into grape clusters in vineyards before harvest.

1b. Approach (from AD-416):
In repeated cluster-directed applications between fruit set and harvest, apply calcium salts, hormonal treatments, reduced-risk fungicides, biological control agents, and other compounds before harvest, then determine their influence postharvest quality (color, texture, maturity, size) and decay (natural incidence of diseases, after artificial inoculation) of table grapes.

3. Progress Report:
Progress in FY12 was made on objective 1A in the parent project. To improve the quality and prolong storage life of fresh grapes, a ‘Thompson Seedless’ vineyard was selected and a variety of chitosan formulations (elicitors of pathogen defense reactions), fungicides, and mineral nutrients were applied to developing grape clusters to determine their impact on berry quality. Berry color, size, firmness, sugar content, and incidence of decay pathogens were measured. The results indicate decreases in decay and a variety of physiological responses occurred within the berries, (particularly by thechitosan formulations). This includes increased endochitinase activity and decreased berry hydrogen peroxide content. One of the chitosan formulations increased quercetin, myricetin, and resveratrol content of the berry skin.

4. Accomplishments

Last Modified: 05/21/2017
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