The purpose of this three-way cooperative project is to develop new fresh-market peach and nectarine varieties in the 400 to 650 chill hour range for the early season shipping market. Since 1990, >3000 seedlings have been evaluated, resulting in 48 selections. Additionally, several hundred selections from other programs have been evaluated. `Sunsplash', an attractive, early season, 400 chill hour nectarine, was released in 1993 as a result of this cooperative effort. A novel aspect of the program has been the use of non-melting flesh parents for the purpose of improving handling characteristics. Selections include both yellow- and white-flesh types, peaches and nectarines. Some may be adapted for use in other production areas and are available for testing under non-propagation agreement. Evaluation summaries of selections and standards will be presented.
T.G. Beckman, W.R. Okie, G. Krewer, and W.B. Sherman
T.G. Beckman, G.W. Krewer, and W.B. Sherman
P. Perkins-Veazie, J.K. Collins, T.G. McCollum, and J. Motes
Four asparagus (Asparagus officinalis L.) cultivars, UC 157, Syn 4-56, Mary Washington, and Viking KB3, were stored at 2C, and their quality was evaluated during 3 weeks of storage, There were no cultivar differences in respiration, weight gain, or soluble solids concentration initially or after storage. After 3 weeks of storage, the cultivars UC and S4 were more vividly green and less seedy than MW or VK, but UC exhibited slight to moderate chilling injury. Spears of S4 and VK had better overall appearance than MW or UC.
Thomas G. Beckman and William R. Okie
Differences in chilling and post-rest heat requirements of various stonefruits were investigated through the use of cuttings collected from field grown trees. Materials studied included P. angustifolia Marsh, P. besseyi Bailey, P. maritima Marsh, P. persica (L.) Batsch (`Agua 6-4', `Flordaking', `Pi Tao', `Redhaven', `Redskin', and `Ta Tao'), P. umbellata Ell. and a Japanese type plum (`Byrongold'). Cuttings were collected after natural leaf fall and shortly after the onset of of chill hour accumulation. Cuttings were stored at 4°C. Groups of cuttings were removed from storage after various amounts of chilling and allowed to develop at 16, 21 or 27°C. Cuttings were observed for both vegetative and flower bud break. Magnitude of differences in chilling and post-rest heat requirements and their implications in the breeding of peaches for low and moderate chill areas will be discussed.
Diana D. Lange and Arthur C. Cameron
Shelf life (defined by visual quality) of freshly harvested greenhouse-grown sweet basil was maintained for an average of ≈ 12 days at 15C. Chilling injury symptoms were severe at storage temperatures of 5C and below. Shelf life was found to be only 1 and 3 days at 0 and 5C, respectively. Moderate chilling injury was noted at 7.5 and 10C. Harvesting sweet basil later in the day (i.e., 1800 or 2200 hr) increased shelf life by almost 100% when harvested shoots were held at 10, 15, and 20C, compared to harvesting at 0200 or 0600 hr. However, the time of day of harvest did not alter the development of visual chilling injury symptoms or improve shelf life at 0 or 5C.
D. Scott NeSmith and Gerard Krewer
Leaf bud development is a problem on many blueberry cultivars grown throughout the Southeast. Dormex (50% hydrogen cyanamide) has shown potential in accelerating leaf and floral bud development of some fruit crops, but its usage on blueberries has not been thoroughly explored. A greenhouse experiment was conducted to examine the effects of timing Dormex applications on `Climax' rabbiteye blueberry (Vaccinium ashei) and `Oneal' southern highbush blueberry (V. corymbosum). Plants were subjected to low and moderate chilling conditions and were forced under greenhouse conditions. Dormex timings were: 1)1 day after forcing (DAF), 2) 3 DAF, 3) at 10% stage 3 floral buds, 4) at 30% to 50% stage 3 floral buds, 5) at 10% to 30% stage 4 floral buds, 6) control (no Dormex). All Dormex applications were applied at a rate of 2% product. Results showed that Dormex both increased and accelerated leaf bud break as compared to the control. However, flower buds at stage 3 of development or beyond were very susceptible to chemical burn by the product. The data indicate that timing of Dormex applications on blueberries should be based on rate of plant development rather than calendar time. Additional research is needed to most effectively use the product to aid blueberry leaf development.
Thomas Beckman, Gerard Krewer, Jose Chaparro, and Wayne Sherman
The primary purpose of the three-way cooperative regional project involving the USDA, University of Georgia, and University of Florida, is to develop improved fresh-market peach cultivars for use in the moderate-chill areas of the southeastern United States. Since 1995, this project has concentrated on the development of non-melting flesh materials as an alternative to conventional melting-type cultivars. It is our belief that the slower softening, non-melting characteristic will allow growers to pick fruit several days later at a more mature stage, thus improving eating quality without sacrificing shipping ability. To date, this program has released three non-melting peach cultivars and is poised to release several more. Through our postharvest evaluations we have been able to demonstrate that these new releases and selections have equal, if not superior, firmness compared to current commercial melting-type cultivars, in combination with higher soluble solids and soluble solids/titratable acidity ratios. Compared to current commercial melting-type cultivars, the new non-melting releases and selections display superior red skin blush, fruit shape, and cropping ability. Moreover, they are of comparable size and have a significantly reduced incidence of split and shattered pits.
Gregory A. Lang and Joshua Tao
Plant dormancy research has long been stifled by the lack of appropriate biochemical markers to characterize the changing physiological status of dormant vegetative or reproductive buds. Two sets of experiments were conducted in an attempt to identify changes in soluble protein profiles during endodormancy of peach and blueberry reproductive apices. Bud samples from the peach cultivars `La Festival' (low chilling requirement) and `La White' (moderate chilling requirement) were taken every 15 days in the orchard during December and January, extracted for soluble proteins, and analyzed by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Outshoots were forced at 25C in a growth chamber to determine the intensity of endodormancy. A further experiment utilized potted `Bluechip' and `Meader' (troth high chilling requirement) blueberry plants given varying periods of cold (4.5C) chamber treatment, followed by forcing at 25C in a growth chamber. Bud samples were taken following cold treatment for extraction and SDS-PAGE. The relationship of the resulting protein profiles to chilling unit accumulation and intensity of endodormancy will be discussed.
Gerard W. Krewer, Thomas G. Beckman, Jose X. Chaparro, and Wayne B. Sherman
Ringspot Virus and Prune Dwarf Virus. Literature Cited Beckman, T.G. Krewer, G. Sherman, W.B. Okie, W.R. 1995 Breeding moderate chill peaches for the lower coastal plain Proc. Fla. State Hort. Soc 108
Jose X. Chaparro, Patrick J. Conner, and Thomas G. Beckman
, Gainesville, FL 32611-0200. Budwood is indexed free of Prunus necrotic ringspot virus and Prune dwarf virus . Literature Cited Beckman, T.G. Krewer, G.W. 1999 Postharvest characteristics of moderate-chill peach varieties Proc. Fla. State Hort. Soc. 112 236