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The discovery and subsequent commercialization of 1-MCP has resulted in intense research interest around the world. A web site (http://www.hort.cornell.edu/mcp/) has been developed which provides a summary of the effects of 1-MCP on climacteric (18 species) and non-climacteric (6) fruits, vegetables (13), fresh cut produce (5), cut flowers and pot plants (more than 50 species has been created. The site is updated on a regular basis. For edible crops, most citations are available for apple (32 citations) and banana (21 citations). The ornamental literature is much less concentrated, and most crops are represented by a single citation. For all commodities, the majority of research has been focused on quality responses of the various products to 1-MCP, although increasingly 1-MCP is being used to investigate physiological and biochemical events associated with development, ripening and/or senescence.

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Most information about the effects of 1-methylcyclopropene (1-MCP) on apple fruit that is available in the literature involves its application immediately after harvest. However, depending on the storage facility, fruit may be treated within a few days of harvest, especially if destined for rapid CA storage, or after longer time periods. We have investigated the effects of: 1) 1, 2, 3, 4, 6, and 8 d delays before 1-MCP treatment on `McIntosh', `Cortland', `Jonagold', `Empire' and `Delicious' apple quality stored in air for 2 and 4 months, and in CA for 4 and 8 months; and 2) 1, 7, 14, and 21 d delays on `Cortland', `Jonagold', `Empire' and `Delicious' apple quality stored in CA for 5 months. `McIntosh' and `Empire' apples were harvested at two maturities. Our data show that responses of apple cultivars to 1-MCP can be affected by delay treatments, but that within each cultivar, these effects vary according to harvest maturity, storage type, and length of storage.

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Production of heat shock proteins (HSP) in response to high temperatures are a highly recognizable feature of plant and animal systems. It is thought that such proteins play a critical role in survival under supraoptimal temperature conditions. The use of heat treatments has been examined extensively, especially for disinfestation of fruit and disease control. Heat treatments can affect physiological responses, such as ethylene production, softening, and other ripening factors, as well as reducing physiological disorders, including chilling injury. HSPs have been implicated in a number of stress responses, but the extent that they are involved, especially in amelioration of chilling injury, is a subject of debate. In a number of cases, heat shock proteins do not appear to be involved, and HSPs do not explain long-term adaptation to heat; other systems for which we do not have models may be at work. Resolution of these issues may require the use of transgenic plants with modified heat shock responses.

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Apple fruits are highly susceptible to superficial scald, which is currently controlled by both chemical- and non-chemical-based technologies. The possible threat of withdrawal of diphenylamine (DPA) for the control of superficial scald has prompted us to investigate the biochemical and molecular aspects of scald resistance. We have selected genetic populations of a cross between `White Angel' and `Rome Beauty' that are resistant and susceptible to scald, and investigated whether the resistance of scald in these populations is due to the higher antioxidant-based defense systems. Cortical tissue of fruits (0–3 cm) was peeled and analyzed for conjugated trienes, H2O2, carbonyl groups, and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidases (POX). Scald-resistant fruits at harvest had higher antioxidant enzymes and low levels of conjugated trienes, carbonyl compounds, and H2O2 levels compared to fruits that are susceptible to scald. Further, H2O2 levels rose in scald-susceptible fruits stored under low temperature with a concomitant increase in the production of conjugated trienes and carbonyl compounds, while no major changes were observed in scald-resistant fruits. Enhanced levels of H2O2 in scald-susceptible populations could be related to enhanced SOD activities and decreased activities of H2O2 degrading enzymes, suggesting that an imbalance between O 2 /H2O2 may have occurred. These results indicate that a coordination between SOD and H2O2 degrading enzymes in scald resistant populations may have minimized the influence of AOS on the oxidation of α-farnesene, protein, and, thereby, on scald. Hence, we have hypothesized that enhancing the potential of apple fruit to metabolize AOS develops resistance to superficial scald. [Supported in part by USDA Specific Cooperative Agreement 58-1931-5-017.]

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`Honeycrisp' apples (Malus × domestica) were harvested over 3-week periods in 2001 and 2002. Maturity and quality indices were determined at harvest. Fruit quality was evaluated after air storage [0.0 to 2.2 °C (32 to 36 °F), 95% relative humidity] for 10-13 weeks and 15-18 weeks for the 2001 and 2002 harvests, respectively. Internal ethylene concentrations (IEC), starch indices (1-8 scale), firmness and soluble solids content (SSC) did not show consistent patterns of change over time. Starch hydrolysis was advanced on all harvest dates, but it is suggested that a starch index of 7 is a useful guide for timing harvest of fruit in western New York. After storage, firmness closely followed that observed immediately after harvest, and softening during storage was slow. No change in SSC was observed during storage in either year. Incidence of bitter pit and soft scald was generally low and was not affected consistently by harvest date. The incidence of stem punctures averaged 18.5% over both years, but was not affected by harvest date. Development of stem end cracking in both years, and rot development in one year, increased with later harvest dates. A panel of storage operators, packers, growers, and fruit extension specialists evaluated the samples for appearance and eating quality after storage, and results suggested that a 2-week harvest window is optimal for `Honeycrisp' apples that are spot picked to select the most mature fruit at each harvest.

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During transport and the subsequent storage of tulip bulbs, inadvertent failure in ventilation and/or high contamination of Fusarium-infected bulbs may expose healthy bulbs to high concentrations of ethylene. Ethylene is known to cause many detrimental effects on forcing quality, including gummosis, increased respiration, flower bud abortion, bulb splitting and poor rooting. In this work, exposure duration and timing as well as the post-stress storage temperatures were evaluated for their potential effects on ethylene sensitivity in bulbs of four tulip cultivars. Degree of damage in sensitive cultivars `Apeldoorn' and `World's Favourite' increased with days at about 10 ppm ethylene starting at 9 and 16 days respectively. This effect strongly depended on timing of ethylene stress, as late treated bulbs showed more severe responses to ethylene treatment than early treated bulbs. Additionally, bulbs that were cooled immediately after ethylene stress, compared with those stored at 17 °C after stress, have significantly higher flowering quality in all attributes measured. This response was also strongly dependent on timing of ethylene stress and cultivar. Implications of the potential cold reversal of ethylene damage as well as effects of ethylene exposure duration and timing of stress on shipping and storage recommendations will be discussed.

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Susceptibility of apple fruit to CO2 can be affected by cultivar and postharvest treatment with diphenylamine (DPA). To study possible metabolic reasons for CO2 injury development, `Cortland' and `Law Rome' apple fruit were either untreated or treated with DPA at harvest, and then exposed to air or 45 kPa CO2 for up to 12 days. Fruit were sampled at 3-day intervals during treatment, and peel and flesh samples were taken for organic acid and fermentation product analysis. Additional fruit were removed to air and stored for 25 weeks for evaluation of injury. `Cortland' apple fruit had more external CO2 injury, but less internal CO2 injury than `Law Rome'. DPA treatment markedly reduced incidence of both external and internal injury. Fermentation products increased in peel and flesh of both cultivars with increasing exposure to CO2. However, acetaldehyde concentrations were ≈10 times higher in peel and flesh of `Law Rome' than `Cortland' apples. Ethanol concentrations in the flesh were similar in both cultivars, but were about twice as high in `Cortland' than `Law Rome' peel. Neither acetaldehyde nor ethanol concentrations were affected consistently by DPA treatment. Cultivar or DPA treatment did not affect accumulation of succinate, often regarded as the compound responsible for CO2 injury. These results do not indicate that acetaldehyde, ethanol, or succinate accumulation is responsible for CO2 injury in apple fruit.

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A sprayable formulation of 1-MCP (250 μL·L-1) and 1% oil adjuvant was applied to `McIntosh' and `Empire' apple trees 24, 14, and 7 days prior to anticipated optimum harvest dates (early, mid-, and late-spray timings, respectively), and fruit harvested sequentially over 2 to 3 weeks from this date. At harvest, internal ethylene concentrations (IEC), percentage of blush, starch indices, firmness, and soluble solids concentration (SSC) were measured, as well as ethylene production of fruit maintained for 7 days at 20 °C. Additional fruit were stored in air (0.5 °C) with or without postharvest 1-MCP treatment. Preharvest drop of `McIntosh' apples was also measured. Quality of these fruit was assessed at intervals for up to 4.5 months (`McIntosh') or 6 months (`Empire'). All spray timing resulted in marked delays of preharvest drop. For both cultivars, increases of IEC were inhibited or delayed by sprayable 1-MCP treatment, but effects on other maturity and quality factors were small. Ethylene production of treated fruit was lower than that of untreated fruit. The effects of sprayable 1-MCP on IEC and firmness were maintained during storage, but the longetivity of these effects was affected by cultivar, spray timing, and storage period. Postharvest application of 1-MCP further inhibited IEC and maintained firmness of the fruit during storage. These experiments show that sprayable 1-MCP may be a valuable tool to manipulate both pre- and postharvest responses of apple fruit. However, with the formulation used in these experiments, phytotoxicity, primarily as damage around lenticel areas, was observed at harvest indicating that further development of the formulation is necessary for industry use.

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The `Empire' apple cultivar is susceptible to external CO2 injury, a physiological disorder that is expressed as tan-colored, smooth, watersoaked areas that become irregularly shaped, rough, depressed, and wrinkled. 1-Methylcyclopropene (1-MCP) may increase susceptibility of fruit to external CO2 injury during controlled atmosphere (CA) storage. We have investigated the effects of 1-MCP on external CO2 injury of `Empire' apple using several approaches. 1) Fruit were treated with 1%, 2.5%, and 5% CO2 during storage. Higher injury levels were associated with exposure to higher CO2 concentrations. 2) Fruit were exposed to 2.5% or 5% CO2 for 3-week periods throughout storage, otherwise being kept at 1% CO2. Most injury occurred in fruit treated with elevated CO2 during the first 3 weeks of storage, and 1-MCP did not extend the period of susceptibility to injury. 3) Exposure of fruit to CA with 5% CO2 after harvest was delayed for up to 14 days. Susceptibility to injury remained high during the delay in 1-MCP-treated fruit in contrast to untreated fruit. 4) Fruit were treated with 250, 500, and 1000 μL·L-1 diphenylamine (DPA), an antioxidant applied for control of superficial scald that is known to prevent susceptibility of fruit to CO2 injury at 1000 μL·L-1. The DPA eliminated injury in 1-MCP treated fruit, even at 250 μL·L-1. Our data show that 1-MCP increases susceptibility of `Empire' apples to external CO2 injury and extra care is therefore required to avoid fruit losses. Nonchemical means may reduce losses, but only DPA application has been shown to eliminate risk of injury.

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