Strawberry runner plants from the cultivar `Selva' (Fragaria ×ananassa Duch.) were produced using three nursery treatments in each of three years: propagation in soil fumigated with a mixture of 2 methyl bromide: 1 chloropicrin (w/w) at 392 kg·ha-1, propagation in fumigated soil but using planting stock inoculated prior to nursery establishment with a conidial suspension of Verticillium dahliae (106 conidia/mL), and propagation in nonfumigated soil naturally infested with V. dahliae. Runner plants were harvested and stored at 1 °C for 6, 18, or 34 days prior to establishment in fruit production trials. No significant differences were found between runner plants grown in naturally infested soil and runner plants obtained from artificially inoculated mother plants for V. dahliae infection rates detected by petiole isolation immediately prior to transplanting, the percentage of plants visibly stunted due to disease during the following production season, and seasonal yield compared with corresponding noninfected controls. Cold storage of runner plants for 18 or 34 days, produced using either natural or artificial inoculation systems, reduced the initial percentage of infected plants by 42% to 61% and the percentage of stunted plants during the following fruit production season by 43% to 57%, compared with plants from corresponding nursery treatments given only 6 days post-nursery cold storage. Yields for inoculated plants with 6 days cold storage were 16% to 20% less than those for uninoculated controls, whereas yields for inoculated plants with 18 or 34 days of storage were 3% to 9% less than the respective controls. Most of the cold storage effects on initial infection rate, stunting, and yield were realized at the 18 days of storage treatment. A reduction in the fraction of V. dahliae infected plants due to cold storage, suggests either a direct effect of cold storage on the disease organism or stimulation of secondary resistance mechanisms in the plant. Chemical name used: trichloronitromethane (chloropicrin).
Douglas V. Shaw, Thomas R. Gordon, and Kirk D. Larson
I. Tayfun Agar, William V. Biasi, and Elizabeth J. Mitcham
Ripening behavior of `Bartlett' pears (Pyrus communis L.), with or without ethylene (C2H4) treatment, was assessed at harvest, and after 2, 4, 6 and 12 weeks of cold storage at –1 °C. Fruit exhibited increasing rates of C2H4 production and consequently faster ripening rates with increased length of cold storage. Ripening characteristics were influenced by storage duration, but to different degrees. The data indicate that the threshold C2H4 concentration for softening may be lower than that for color change from green to yellow. Ethylene treatment for 24 h at harvest resulted in a rate of ripening equivalent to that following cold storage for 2 to 4 weeks, depending on the orchard location. Storage for 12 weeks significantly increased C2H4 production upon transfer to ambient temperature, indicating that fruit were reaching the end of their storage life. `Bartlett' pears may ripen to a firmness of 14 N (ready to eat) at 20 °C within 2.5 to 7 days depending upon the duration of prior cold storage.
Federica Galli, Douglas D. Archbold, and Kirk W. Pomper
Poster Session 52—Postharvest Storage 21 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F
C.D. Grote-Flores, G.V. Latigo, J.O. Bradford, and J.O. Kuti
Guayule shrub (Parthenium argentatum Gray) is a source of natural rubber resin and latex. Because guayule does not produce natural antioxidants, considerable amounts of rubber and resin are lost after harvest. The effect of long (2–7 years) cold storage on postharvest stability of rubber and resin contents in selected dryland guayule breeding lines were compared. While most genotypes tested showed significant decline in rubber and/or resin content during the storage, few genotypes consistently maintained or increased the amounts of rubber or resin content during storage. The mechanisms of postharvest degradation or synthesis of rubber and resin in harvested guayule plant materials need to be studied further.
George J. Wulster and Thomas J. Gianfagna
Growth and flowering of Freesia hybrida Bailey for the container-plant market can be controlled chemically using growth retardants and environmentally by cold storage of corms at 5C for 2 to 6 weeks before planting. Corms stored at 5C for 4 weeks flowered 20 days earlier than corms not stored at 5C. Preplant 5C storage of corms also reduced leaf and flower height. An ancymidol soil drench (3 mg) reduced leaf height and flower height by more than 50% and delayed flowering by 9 days. Combining growth regulator application with cold storage of corms produced the greatest reduction in leaf height and flower height. Moreover, plants flowered earlier than controls when corms were stored for at least 4 weeks, regardless of growth regulator treatment. Chemical name used: α-cyclopropyl-α- (4-methoxyphenyl) -5-pyrimidine methanol (ancymidol).
Robert L. Wample and Andy Bary
Cold-hardiness evaluations and soluble and insoluble-nonstructural carbohydrate analysis of dormant Vitis vinifera L. cv. Cabernet Sauvignon buds and cane tissue indicate a positive relationship between soluble carbohydrates and primary bud cold hardiness. Seasonal variations in soluble and insoluble carbohydrates appear to be related to changes in air temperatures and the dormancy status of the tissues. No differences were found in bud cold hardiness and only limited differences in carbohydrate levels of buds or stem tissues collected over 3 years from early harvest, normal harvest, or unharvested vines. These findings contrast with the widely held opinion that delayed harvest or failure to remove fruit results in reduced cold hardiness as a consequence of low storage carbohydrate content of the plants.
Karen L.B. Gast
40 POSTER SESSION 3 (Abstr. 092-104) Postharvest Physiology/Storage/Food Science Monday, 24 July, 1:00-2:00 p.m.
James A. Okeyo and Mosbah M. Kushad
`Atlantic', `BelRus', `Kennebec', and `Superior' potatoes (Solarium tuberosum L.) were evaluated for ascorbic acid, soluble protein, and sugar content (reducing and nonreducing) at harvest, after 6 weeks of storage at 3C, and after 2 weeks of reconditioning at 25C. At harvest, ascorbic acid and soluble protein contents varied among the cultivars, with `Superior' containing the highest ascorbic acid (154 mg/100 g dry weight) and soluble protein content (46.4 mg·g−1 dry weight). Cold storage resulted in a drastic reduction (±50%) in ascorbic acid content in all four cultivars. Ascorbic acid also decreased during reconditioning of tubers, but the reduction was less than during cold storage. In contrast, soluble protein contents were not influenced significantly by cold storage or reconditioning, except for `BelRus' and `Kennebec', which had less protein after reconditioning. At harvest, glucose, fructose, and sucrose contents were at similar levels in all cultivars, except for fructose in `Kennebec', which was more than 2-fold higher. `Kennebec' also had a significantly lower specific gravity than the other cultivars. However, unlike the other cultivars, reconditioning of `Kennebec' tubers did not affect its specific gravity or total sugar content. Data suggest that `Kennebec's' poor processing quality may have resulted from a combination of low specific gravity and high total sugar content.
Fumiomi Takeda Takeda, Stan Hokanson*, John Enns, Penelope Perkins-Veazie, and Harry Swartz
`Chandler' strawberry plants were propagated in tissue culture and grown from April to August in a protected environment to produce stolons. July-harvested daughter plants were stuck in cell packs with rooting media and placed under mist sprinklers, or cold stored at 2 °C for 42 days. Among the July transplants, some were kept in the greenhouse until field planting (14 Sept.) and others were moved into a cold room on 14 August. Daughter plant size and position on the stolon affected rooting and quality of transplants. July-harvested daughter plants that were plugged and misted after being cold stored for 42 days developed fewer roots than daughter plants plugged immediately after detaching from mother plants in July or August. In the field, transplants produced from daughter plants harvested in July and cold stored for 42 days developed more stolons than transplants from July- and August-harvested daughters that were not exposed to cold storage treatments. Larger daughter plants produced more branch crowns than did smaller daughter plants during the fall. All transplants from daughter plants harvested in July and propagated without cold treatment bloomed by November. Fruit production ranged from 521 to 703 g per plant. `Chandler' plants from daughter plants that weighed 10 g produced 10% greater yield than those that weighed <1.0 g. Plants generated from daughter plants plugged in July produced 26% more fruit than those plants plugged in August. Greenhouse soilless systems can be used to grow `Chandler' mother plants for generating runner tips and transplants for the annual plasticulture in colder climates. `Chandler' plants produced in July can yield a late fall crop under high tunnels and more fruit in the spring than August-plugged transplants
Rick M. Bates and Alexander X. Niemiera
Shoot and root water potentials were determined for bare-root Norway maple (Acer platanoides L.) and washington hawthorn (Crataegus phaenopyrum Med.) seedlings subjected to shoot and root exposure treatments for six cold storage durations. Shoot and root water potentials for all exposure treatments and both species decreased with increased time in storage, and the greatest degree of water stress occurred during the first six weeks of storage. Maple shoot and root water potentials for the exposed shoot treatment were the same as the whole plant covered treatment. In contrast, hawthorn shoot and root water potentials for the exposed shoot treatment were the same as values for the roots exposed treatment. Based on these data, we conclude that desiccation sensitive species such as washington hawthorn require root and shoot protection to minimize water loss.