`Fino de Jete' cherimoya fruit were stored at 20, 10, 8, or 6C, 80% relative humidity. Two rises of CO2 production and an ethylene rise following the first peak of respiration were obtained in fruit held at 20C. The ripe stage coincided with the onset of the second respiratory rise. Soluble sugar and organic acid concentration were maximal, and flesh firmness was 18 N in ripe fruit. Lower temperature reduced respiration rate and ethylene production; however, some stimulation of ethylene synthesis was observed at 10C. Cherimoyas ripened to edible condition during 6 days at 10C, but fruit maintained at 8C for up to 12 days required transfer to 20C to ripen properly. Our results suggest that high increases in CO2 are not sufficient to complete cherimoya fruit ripening without the concurrent rise in ethylene production. Citric acid accumulation, inhibition of ethylene synthesis, and reduced accumulation of sucrose were observed during storage at 6C. Removal to 20C after 12 days at 6C resulted in no ripening, almost complete inhibition of ethylene synthesis, and severe skin browning. Thus, 8C is the lowest tolerable temperature for prolonged cold storage of cherimoya `Fino de Jete'. Fruit can be held at 8C for up to 12 days without damage from chilling injury.
Rafael Alique, José P. Zamorano, Ma Luisa Calvo, Carmen Merodio, and José L. De la Plaza
Ahmad Sattar Khan and Zora Singh
postharvest application of polyamines ( Serrano et al., 2003 ), aminoethoxyvinylglycine ( Jobling et al., 2003 ), and 1-methylcyclopropene (1-MCP) ( Khan and Singh, 2007 ; Watkins, 2006 ); edible coating ( Navarro et al., 2005 ); cold storage ( Robertson et
Douglas V. Shaw, Thomas R. Gordon, and Kirk D. Larson
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).
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.
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).
M.R. Pooler and P.W. Simon
The effects of cold storage, photoperiod, and growth temperature on flowering incidence in four clones of garlic (Allium sativum L.) were studied. While flowering percentage was influenced most by clone, interactions with photoperiod, growth temperature, and storage occurred. Clone R81 flowered equally well in all conditions, whereas flowering percentage of clones D129, D130, and PI485592 was reduced by cold (4C) storage of either bulbs or plants, long (16-h) photoperiod, and at 18C relative to 10C. The highest flowering percentage in all garlic clones was achieved by growing plants at 10C under short (9- to 10-h) photoperiod with no cold storage of bulbs before planting.
Federica Galli, Douglas D. Archbold, and Kirk W. Pomper
Pawpaw[Asiminatriloba (L.) Dunal] is a highly perishable climacteric fruit. Generally, fruit may be stored at 4 °C for 4 weeks with minimal loss in quality or subsequent ripening capacity. However, comparisons among cultivars and advanced selections for ripening behavior and postharvest storage life have not been reported. Ideally, cultivars with superior ripening traits (higher firmness, or a slower rate of firmness loss) and longer storage life may be identified for the commercial market. To determine if differences among genotypes may exist, respiration, C2H4 production, and fruit firmness of six varieties, 8-20, 9-58, `Middletown', `PA Golden', `Taytwo', and `Taylor', were measured during ripening after harvest and after 1, 2, 3, 4, 5, and 6 weeks of 4 °C storage. No differences were observed among the cultivars regarding respiration and C2H4 production. Respiratory and ethylene peaks were detected within 48 hours after harvest or removal from cold storage. Rapid loss of firmness was measured during ripening at ambient temperature after harvest and after removal from cold storage (days 0–3), with some loss during cold storage itself (weeks 1–6). As expected, firmer fruits at harvest had a lower respiration rate. However, no obvious differences in ripening behavior or cold storage response were observed among the six genotypes. As a general guideline, only firmer fruits should be cold stored, since fruit softening did not stop at 4 °C. A broader analysis of all of the named cultivars and advanced selections of pawpaw will be needed to determine if the present results are generally representative of pawpaw.
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.
Jinwook Lee, James P. Mattheis, and David R. Rudell
rootstock ( Fallahi et al., 2013 ), irrigation ( Opara et al., 2000 ), nutrient management ( Opara et al., 1997b ; Perring, 1984 ), and fruit maturity ( Byers, 1998 ; Opara et al., 1997b ). During and after cold storage, fruit size positively contributes
Mariya V. Khodakovskaya, Richard J. McAvoy*, Hao Wu, and Yi Li
It has been reported that constitutive expression of the fatty acid desaturase enzyme increased the trienoic fatty acid content of thylakoid membranes in transgenic tobacco, allowing the membranes to remain fluid under cold conditions. While increased cold tolerance resulted from this genetic modification, plants with a constitutively expressed desaturase enzyme would not be particularly well suited for growth under warm temperatures. To increase the ability of plants to tolerate prolonged cold-storage and still perform under greenhouse production conditions (25 °C), a unique cold-inducible genetic construct was cloned and tested. The FAD7 gene, which encodes an omega-3-fatty acid desaturase enzyme, was put under the control of a cold-inducible promoter (cor15a) from Arabidopsis thaliana. Transgenic petunia plants (cv, Marco Polo Odyssey) harboring cor15a:FAD7 were established and conformed by PCR and Southern analysis. Therefore in our study, FAD7 gene expression was induced by exposure to cold temperatures and down regulated under normal growing conditions. RT-PCR indicated a marked increase in FAD7 expression between transgenic plants exposed to a short (3 days) cold treatment prior to long-term cold storage and those that did not receive a cold induction treatment. Transgenic and wild-type plants were induced in cold (3 °C) for 3 days, returned for normal greenhouse conditions for 5 days and then subjected 3 weeks of continuous cold storage. It was observed that two out of eight transgenic lines showed superior cold tolerance relative to wild-type petunia plants. Additionally, plants that showed cold tolerance completely recovered; growing and flowering normally when returned to the 25 °C greenhouse conditions.