Leah Groves,* Sonet Van Zyl, Anil Shrestha, and Stephan Sommer
*California State University, Fresno, 2360 E. Barstow Avenue, M/S VR89, Fresno, CA, 93740 (groves_leah@mail.fresnostate.edu)

California is a leader in producing table grapes, making postharvest storage an es­sential component of worldwide distribution. A common struggle in the table grape industry is grape waste due to berries with poor integrity. There have been studies to extend postharvest storage by applying preharvest applications like calcium chloride, calcium nitrate, and sodium bicarbonate. Yet no study has indicated calcium carbonate usage, especially in agriculture. Calcium carbonate could be useful in plant physiology, as calcium is important for berry cell wall structural components and car­bonate can be essential in photosynthesis. However, calcium carbonate is insoluble, and due to its large particle size, not easily absorbed by plants. This study evaluated OR-244B, a calcium carbonate-based product that has a small particle size, in the Fresno State Vineyard. Sweet Scarlet, a red midseason seedless table grape, was used to evaluate calcium carbonate uptake and its effect on grapes after commercial cold storage trials. The cultural and harvest practices followed a conventional operation, with grapes packed into 19 lb boxes. The experimental layout consisted of eight treatments, including a control, with six replicates. OR-244B was compared with the individual components and standard industry products containing calcium. The treat­ments included foliar and soil applications during the growing season. After harvest, grapes were stored for four and eight weeks at a commercial cold storage facility. Berry texture, size, color, and fungal infection rates were used to evaluate OR-244B as a cheaper and safer calcium-based product to increase postharvest storage quality.

Funding Support: ORO AGRI, Inc., Agricultural Research Institute