|CHRISTENSEN, L. PETER|
Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2008
Publication Date: 9/17/2008
Citation: Christensen, L., Fidelibus, M.W., Katayama, D.G., Ramming, D.W. 2008. Early-ripening grapevine cultivars for dry-on-vine (DOV) raisins on an open-gable trellis. HortTechnology:18(4):740-745.
Interpretive Summary: The traditional production of raisin grapes in California has depended on hand labor to harvest the crop and lay it on paper trays in the field to dry. Labor has become less available and more costly, making mechanization of raisin production an important industry goal. Thompson Seedless, the principle raisin variety grown in California matures late and is not suitable for cutting of the fruiting canes and drying the fruit on the trellis (DOV) for mechanical harvest. New earlier ripening raisin varieties have been developed and were tested for their adaptability to DOV under three training systems. The training system did not affect fruit composition, raisin yield or quality. Selma Pete grapes matured as early or earlier than the other varieties with comparable or better production and quality. DOVine grapes had many of the same desirable traits as Selma Pete but did not dry as well. Diamond Muscat grapes ripened early, dried well, and produced good quality raisins but had lower yields. Fiesta grapes ripened the slowest and did not always have adequate sugar to make high quality raisins. Selma Pete appears to be the best choice for making DOV raisins on an open gable trellis.
Technical Abstract: ‘Diamond Muscat’, ‘DOVine’, ‘Fiesta’, and ‘Selma Pete’ grapevines were evaluated to determine their suitability for making DOV raisins on an open gable trellis. The experiment was a split-plot, with training system, head, bilateral, or quadrilateral training, as the main plot, and grapevine cultivar, ‘Diamond Muscat’, ‘DOVine’, ‘Fiesta’, or ‘Selma Pete’, as the sub-plot. Yield components, fruit composition, and raisin yield and quality were evaluated each year. In general, vine training style did not affect fruit composition, or raisin yield or quality. However, vines trained to quadrilateral cordons produced more clusters on renewal shoots compared to head-trained vines. ‘DOVine’, ‘Fiesta’, and ‘Selma Pete’ produced about 4.75 tons of raisins per acre, about 10% more than ‘Diamond Muscat’. ‘Fiesta’ grapes matured later than the others, so it had the lowest soluble solids, the poorest raisin grades, and the highest field moisture at harvest. In contrast, ‘Selma Pete’ had among the earliest cane cut dates, highest soluble solids and raisin grades, and its raisins generally dried well. ‘Diamond Muscat’ produced the lowest yields, but its raisins were of good quality.