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Renae E. Moran

The goal of this project was to evaluate the effectiveness of aminoethoxyvinylglycine (AVG) for increasing effectiveness of 1-methylcyclopropene (1-MCP) for maintaining firmness and preventing scald in `McIntosh' and `Cortland' apples (Malus ×domestica). AVG and 1-MCP used together maintained `McIntosh' apple firmness more than 1-MCP used alone after 120 or 200 days of controlled-atmosphere (CA) storage. AVG and 1-MCP can be used to maintain firmness of `McIntosh' when internal ethylene concentration (IEC) at harvest is as high as 240 μL·L-1, but CA storage life is limited to 4 months. AVG was not effective at increasing efficacy of 1-MCP on `Cortland' when IEC at harvest was not significantly different between AVG-treated and untreated fruit and IEC was less than 2 μL·L-1. AVG increased efficacy of 1-MCP on `Cortland' when IEC was 36 μL·L-1 in untreated fruit compared to undetectable in AVG treated fruit. 1-MCP prevented scald of `Cortland' in 1 year and reduced it to 5% or less in another year when fruit were stored 120 days. 1-MCP reduced `Cortland' scald to 34% or less after 200 days of storage.

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R.E. Moran

The objective was to test the efficacy of 1-MCP when applied at 1, 4, 7, or 10 days after harvest. At harvest, internal ethylene (IEC) was undetectable in most fruit. There was a large increase in concentration at 7 days after harvest and an additional increased at 10 days in `McIntosh'. In Cortland, IEC was very low or undetectable until 10 days after harvest. After 4 months in CA storage, firmness of untreated `McIntosh' fell below 53 N. 1-MCP applied 1 day after harvest maintained firmness more than later applications. Application at 4–10 days was also effective with little difference between the three dates. 1-MCP was most effective on `Cortland' when applied 1–7 days after harvest. At 10 days, there was a loss of efficacy in maintaining firmness. Similar results occurred after 7 months of CA storage. Superficial scald of `McIntosh' was very mild with <1% of the fruit being affected after 220 days storage and 7 days at 20 °C. Untreated `Cortland' fruit had the greatest incidence of scald with most of the fruit being affected by 200 days. 1-MCP was not effective in preventing scald in `Cortland'.

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John M. DeLong, Robert K. Prange, and Peter A. Harrison

`Redcort Cortland' and `Redmax' and `Summerland McIntosh' apples (Malus ×domestica Borkh.) were treated with 900 nL·L-1 of 1-methylcyclopropene (1-MCP) for 24 hours at 20 °C before storage and were kept at 3 °C in either a controlled atmosphere (CA) of 2 kPa O2 and <2.5 kPa CO2 or in an air (RA) environment for up to 9 months. After 4.5 months, half of the fruit were treated with a second 900 nL·L-1 1-MCP application in air at 3 °C for 24 hours and then returned to RA or CA storage. At harvest and following removal at 3, 6, and 9 months and a 7-day shelf life at 20 °C, fruit firmness, titratable acidity (TA) and soluble solids content (SSC) were measured, while internal ethylene concentrations (IEC) in the apple core were quantified after 1 day at 20 °C. Upon storage removal and following a 21-day shelf life at 20 °C, disorder incidence was evaluated. 1-MCP-treated apples, particularly those held in CA-storage, were more firm and had lower IEC than untreated fruit. Higher TA levels were maintained with 1-MCP in all three strains from both storages, while SSC was not affected. Following the 6- and/or 9-month removals, 1-MCP suppressed superficial scald development in all strains and reduced core browning and senescent breakdown in RA-stored `Redmax' and `Summerland' and senescent breakdown in RA-stored `Redcort'. 1-MCP generally maintained the quality of `Cortland' and `McIntosh' fruit held in CA and RA environments (particularly the former) to a higher degree than untreated apples over the 9-month storage period. A second midstorage application of 1-MCP at 3 °C did not improve poststorage fruit quality above a single, prestorage treatment.

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Zhanyuan Du and William J. Bramlage

Ethephon and diphenylamine (DPA) were used to examine the role of ethylene production in biochemical changes that precede development of superficial scald on `Cortland' apples (Malus domestica Borkh.) after cold storage. Treatments modified α-farnesene and conjugated triene (CT) accumulations in fruit peel, and their effects on CTs differed depending on whether CTs were measured at 258 nm (CT258) or 281 nm (CT281). Ethephon induced rapid and delayed effects on fruit, the former being stimulation of ethylene production and α-farnesene and CT accumulation in fruit peel, which could increase scald development, and the latter being a disproportionately higher accumulation of CT258 than of CT281 during prolonged cold storage, which was associated with reduced scald development. DPA treatment at harvest also produced rapid and delayed effects. It immediately reduced ethylene synthesis and α-farnesene and CT accumulation. In addition, during fruit storage at 0C, DPA reduced accumulation of CT281 more than that of CT258. The rapid and delayed effects of DPA should contribute to less scald development. These results showed that ethylene probably was involved in effects of ethephon and DPA on scald development and suggest that ethylene has a fundamental role in changes associated with superficial scald development.

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Jennifer R. DeEll, H.P. Vasantha Rupasinghe, and Dennis P. Murr

`Cortland' is an apple cultivar with inherent poor storeability because of excessive vulnerability to the development of superficial scald in long-term storage. The objectives of this investigation were to evaluate the potential of the potent ethylene action inhibitor 1-methylcyclopropene (1-MCP; EthylBloc®) to counteract this constraint and to develop some basic procedures for its exposure. Eight hours after harvest, fruit were exposed to 1.0 mL·L–1 1-MCP for 0, 3, 6, 9, 12, 16, 24, or 48 h at 3, 13, or 23 °C. Following exposure, fruit were placed at 0 to 1 °C in air for 120 days, after which time they were removed to 20 °C and held 7 days for post-storage assessment of ripening and to allow development of physiological disorders. In general, and within our experimental limits, the higher the temperature of 1-MCP exposure the shorter the required exposure time to obtain similar effects. The desired effectiveness of 1-MCP could be achieved by exposing fruit for at least 3 h at 23 °C, for 6 h at 13 °C, or for 9 h at 3 °C. 1-MCP-treated apples were consistently 2 kg firmer than untreated apples. Scald incidence in untreated fruit after 120 days at 0 to 1 °C and 7 days at 20 °C was 100%, whereas 1-MCP reduced scald by 95% in treatments of long enough duration at any particular temperature.

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J. Pablo Fernández-Trujillo, Jacqueline F. Nock, and Christopher B. Watkins

`Cortland' and `Law Rome' apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] were either nontreated or treated with the inhibitor of superficial scald development, DPA, and exposed to air or CO2 (40 or 45 kPa) in air at 2 °C for up to 12 days. Fruit exposed to air or 45 kPa CO2 were sampled during treatment, and peel and flesh samples taken for fermentation product and organic acid analyses. After treatment, fruit were air stored for up to 6 months at 0.5 °C for evaluation of disorder incidence. `Cortland' apples were most susceptible to external CO2 injury and `Law Rome' to internal CO2 injury. 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, but the extent of the increase was cultivar dependant. Acetaldehyde concentrations were about 10 times higher in peel and flesh of `Law Rome' than that of `Cortland' apples. Ethanol concentrations in the flesh were similar in both cultivars, but were about twice as high in `Cortland' than in `Law Rome' peels. Neither acetaldehyde nor ethanol concentrations were affected consistently by DPA treatment. Succinate concentrations, often regarded as the compound responsible for CO2 injury, increased with CO2 treatment, but were not affected by DPA application. Citramalate concentrations were reduced by CO2 treatment in `Law Rome' peel, but other acids were not consistently affected by CO2. Results indicate that acetaldehyde, ethanol or succinic acid accumulation are not directly responsible for CO2 injury in apples. Chemical name used: diphenylamine (DPA).

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Nazir Mir, Rufino Perez, and Randolph M. Beaudry

`Cortland' apples (Malus ×domestica Borkh.), either untreated or treated with diphenylamine (DPA), were stored for 120 days in air at 0 °C. Peel samples were taken from these fruit immediately after storage, placed in glass vials and incubated for 48 hours, or were isolated from fruit held 2 to 72 hours at 22 °C and incubated in the vials for 2 hours. Emission of 3,7,11-trimethyldodeca-1,3(E),6(E),10-tetraene, known as trans,trans-α-farnesene, or simply α-farnesene, and its oxidation product, MHO, were measured in the vial headspace. α-Farnesene content in the gas phase of vials with peel samples reached a maximal level 2 hours after vials were sealed and was higher in DPA-treated than untreated fruit. The content of α-farnesene in the vial headspace remained unchanged for DPA-treated fruit peel during the 2-day holding period. However, α-farnesene declined rapidly after 10 hours incubation for control samples. Incubating peel samples of control fruit under N2 atmosphere prevented the decline in α-farnesene. The MHO release by the peel of control fruit was rapid during the first 2 hours and continued to increase for 24 hours. In contrast, the MHO released from DPA-treated fruit peels was 8000-fold lower than from peel samples of control fruit. The increase in vapor phase MHO was concomitant with peel browning in controls. For whole fruit held at 22 °C for 2 to 72 hours, cumulative MHO release from fruit peels followed a pattern that was similar to the pattern of superficial scald development in these fruit.

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Jennifer R. DeEll and Robert K. Prange

Postharvest quality and sensory attributes of organically and conventionally grown `McIntosh' and `Cortland' apples (Malus domestica Borkh.) stored at 3C in ambient air or in controlled atmospheres were evaluated. Organically grown apples had higher soluble solids concentration than conventionally grown apples, while there were no significant differences in firmness or titratable acids content. Organically grown `McIntosh' were perceived by sensory panelists as firmer than conventionally grown `McIntosh' at harvest but not after storage, which may have been due to maturity differences. No significant differences were perceived in juiciness, sweetness, tartness, and off-flavor of apples at harvest or after storage.

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Zhanyuan Du and William J. Bramlage

Ethephon treatments had two opposing effects on scald induction. First, synthesis and metabolism of α- farnesene were immediately enhanced, which could increase scald development. Second, during prolonged storage the relative concentrations of two conjugated triene forms (CT281 and CT258) were altered so as to increase the CT258/CT281 ratio, which could reduce scald development. The balance between these responses determined whether ethephon increased or decreased scald. DPA treatment also had two effects, immediately suppressing ethylene and α- farnesene concentrations, and over long periods, suppressing CT281 but increasing CT258 concentrations. Both effects of DPA appeared to reduce scald development. Effects of DPA, as well as of ethephon, were at least partly ethylene - mediated, and treatment with DPA counteracted effects of an ethephon treatment.

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Christopher J. D’Angelo and Irwin L. Goldman

the critical vernalization period and optimum chilling time for long-day onion. The F 1 hybrid cultivar Cortland (Bejo Seeds, Oceano, CA) was used for field experiments in 2013. In 2014, the experiment was expanded to include both ‘Cortland’ and the F