Location: Horticultural Crops Research
Project Number: 2072-21000-053-01-G
Project Type: Grant
Start Date: Sep 1, 2017
End Date: Sep 30, 2019
1. To investigate the mechanism of cell wall hardening during grape ripening; 2. To mitigate grape berry splitting by enhancing cell wall hardening in the berry skin; 3. To provide recommendations to growers in the Pacific Northwest region regarding mitigation of grape berry splitting.
We will use field-grown grapevines with distinct genetic backgrounds (Merlot and Concord). These two varieties provide an excellent model system to study berry splitting, since Merlot is resistant to splitting, whereas Concord is highly susceptible. Berry samples will be collected repeatedly during ripening from the Washington State University (WSU) research vineyards in Prosser. Total soluble solids (TSS) will be measured as a simple maturity index. The metabolism of reactive oxygen species will be examined in the berry skin and flesh. We will target two groups of enzymes. Data will be analyzed by analysis of variance (ANOVA) to test for effects of variety and stage of maturity. We will use Concord vines in the WSU Research vineyard. At the onset of berry softening, spermidine will be sprayed on the clusters to facilitate cell wall hardening. Berries will be sampled from treated and control vines through harvest to assess splitting rates. Splitting rates over time will be analyzed by the Proportional Hazards Model. Another group of berries will be mounted on a custom-designed berry strength tester. Berries will be harvested to determine berry size, the degree of splitting, TSS, pH, and titratable acidity. Data will be analyzed by ANOVA.