Submitted to: National Berry Fruit Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 27, 1998
Publication Date: N/A
Interpretive Summary: Recent research has refined the techniques for using gibberellic acid (GA3) to improve poor fruit set and yield of rabbiteye blueberries caused by inadequate pollination. Many growers in the southeastern United States routinely apply GA3 at bloom to overcome moderate freeze damage or to compensate for anticipated pollination stresses. The objectives of this study were to determine the effects of GA3 on those chemical composition and physical properties when often are used as parameters to assess fruit quality and to see if GA3 affects these parameters after refrigerated storage. Compositional parameters measured in the study were: ph, titratable acidity, soluble solids concentration, sugar/acid ration, anthocyanin, specific sugars and organic acids. Physical properties measured were skin toughness, attached pedicels, berry weight, weight loss during storage, firmness, decay and shrivel. There were no consistent (across all cultivars) effects of GA3 on any of the parameters. Differences in soluble solids content within cultivars are thought to be caused by fruit maturity rather than GA3. There were no changes in poststorage values of any parameter attributable to GA3. The results of this study indicate that quality of rabbiteye blueberries from GA3-treated plants would be equivalent to that of fruit from untreated plants. Growers should be able to take advantage of the proven ability of GA3 to help reduce yield loss from poor pollination situations without reducing fruit quality.
Technical Abstract: Plants of rabbiteye blueberry (Vaccinium ashei Reade) cultivars Climax, Premier and Tifblue were sprayed at bloom with a water solution of 100 ppm gibberellic acid (GA3). Spray treatments were repeated 10-12 days later. Blooms had not been damaged by cold weather nor was pollination influenced by any known stresses. Fruit were analyzed at harvest, stored 21 days at 2-3C and analyzed poststorage to determine the effects of GA3 on physical and chemical parameters routinely used to assess storage quality. There were no consistent (across all cultivars) effects of GA3 on any of the parameters. Soluble solids concentrations (SSC) of fruit from Climax and Tifblue plants treated with GA3 were lower than those of fruit from untreated plants. Premier fruit from GA3-treated plants had higher SSC and after storage were firmer and showed less decay than fruit from untreated plants. Tifblue fruit from treated plants were higher in anthocyanins at harvest but showed more poststorage decay than fruit untreated plants. Treatment x storage interactions for the objectively-determined parameters were not significant.