Search

The objective of this study was to evaluate the timing of ethylene inhibition with preharvest and postharvest 1-methylcyclopropene (1-MCP) treatments on internal browning and quality of 'Gala' apples in long-term low O2 storage. 'Gala' apples were obtained from the same commercial orchard during their harvesting period for 2 years of study. Preharvest 1-MCP orchard spray (3.8% a.i) was applied at the label rate of 60 g 1-MCP per acre in the first year. Postharvest 1-MCP (1 μl L−1) treatments were made for 24 h at 0.5°C either at harvest time (1 day after harvest) or after storage in controlled atmosphere (CA) in both years. Apples were stored in 1.5 kPa O2 + 0.5 kPa CO2 or 0.6 kPa O2 + <0.5 kPa CO2 for 9 months in the first year and 1.5, 1.0, or 0.5 kPa O2 + 0.5 kPa CO2 for 8 months in the second year. Storage regimes with O2 concentrations less than 1 kPa were based on fruit respiration using SafePod™ technology. After removal from storage, all apples were then evaluated for internal browning and other quality attributes after 1, 7, and 14 days at room temperature (RT, 21–22°C). Internal browning developed in 'Gala' apples during both years of study, with up to 16% incidence across treatments in the first year and up to 84% in the second year. Apples stored in 0.5–0.6 kPa O2 had significantly less internal browning during both years of study, compared to apples stored in higher O2. The effect of 1-MCP on internal browning was negligible in 0.5–0.6 kPa O2 storage. 'Gala' stored in 1.5 kPa O2 and treated with postharvest 1-MCP after storage had significantly less internal browning with preharvest 1-MCP than those without preharvest treatment. Apples treated with postharvest 1-MCP at harvest time, instead of after storage, did not exhibit this same effect. Preharvest 1-MCP-treated fruit maintained greater firmness retention than those without preharvest 1-MCP, and this effect was further enhanced when 1-MCP was applied after storage. Postharvest 1-MCP had no effect on firmness retention in fruit without preharvest 1-MCP, but lower O2 maintained greater firmness in those apples. Preharvest 1-MCP had no significant effect on internal ethylene concentration, whereas it was reduced by postharvest 1-MCP at harvest time in the first year of study, regardless of storage regimes. However, internal ethylene was only affected by storage regime in the second year, with lower concentration in fruit from 0.5 kPa O2 than in those from higher O2. Greasiness developed only in the second year and postharvest 1-MCP consistently reduced it, regardless of treatment timing and storage regime. There was no greasiness in apples treated with postharvest 1-MCP at harvest and then held in 0.5 kPa O2 for 8 months plus 14 days at room temperature. Soluble solids concentration and malic acid content were slightly higher in 'Gala' apples with preharvest 1-MCP compared to those without, whereas there was little and inconsistent effect of postharvest 1-MCP on these attributes. Overall, storage regimes with less than 1 kPa O2 provided the least amount of internal browning and best quality attributes. Ethylene inhibition provided further benefits, but this was dependent on the timing of 1-MCP treatment. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this study was to investigate the effects of low-oxygen storage and 1-methylcyclopropene (1-MCP) on disorders and quality of 'Empire' apples. For 2 years, 'Empire' apples were obtained from commercial orchards during their harvesting period. After cooling overnight at 3 °C, the apples were treated with or without 1-MCP (1 μL·L-1) for 24 hours and subsequently stored in controlled atmosphere (CA) with 2.5 kPa O2(+2 kPa CO2) or 1.5 kPa O2(+1.2 kPa CO2) for 8 months at 1.5 and 3 °C for the first and second year, respectively. In the second year, a third group of the 'Empire' apples was also held in respiratory quotient (RQ)-based dynamic CA storage (SafePod) that reached 0.6 kPa O2(+0.5 kPa CO2), and half of these apples were treated with 1-MCP (1μL·L-1) for 24 hours at 3 °C upon removal after 8 months. All apples were then evaluated for disorders and quality after 1, 7, or 14 days at room temperature (RT, 23 to 24 °C). Substantial external CO2 injury, flesh browning, and core browning (up to 38% incidence) developed in 'Empire' stored in 2.5 and 1.5 kPa O2during both years of study. Storage in 1.5 kPa O2 reduced flesh browning in the first year and core browning during the second year in apples without 1-MCP, as compared to storage in 2.5 kPa O2. 1-MCP-treated apples stored in 2.5 or 1.5 kPa O2 had higher overall incidence of disorders than similar fruit without 1-MCP. In contrast, there was negligible incidence (0% to 1%) of these disorders in 'Empire' apples held in 0.6 kPa O2, regardless of 1-MCP treatment upon removal. Storage in 0.6 kPa O2 also resulted in the greatest fruit firmness retention while at RT for 14 days. This regime can provide flexibility to postpone 1-MCP treatment until after storage, to prevent increased susceptibility to disorders during storage, without compromising fruit quality. However, results from the RQ-based dynamic CA with 0.6 kPa O2 were from a single season, and further research is needed to confirm these observations. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of elevated carbon dioxide (CO 2 ) associated with storage room loading on fruit quality and external CO 2 injury in ‘McIntosh’ and ‘Empire’ apples. Effects of fruit cooling rate and the postharvest application of 1-methylcyclopropene (1-MCP) were also evaluated. Over two consecutive years, two strains of ‘McIntosh’ (Pioneer and Summerland) and ‘Empire’ apples were harvested from orchards during the commercial harvest period. In the first year, both strains of ‘McIntosh’ were cooled rapidly to 3 °C and treated with 1-MCP (1 μL L −1 ) overnight. In the second year, half of the apples from each ‘McIntosh’ strain and ‘Empire’ were cooled rapidly to 3 °C, while the other half were cooled slowly from ∼22 °C down to 14–16 °C. All ‘McIntosh’ and half of the ‘Empire’ fruit from each cooling regime were also treated with 1-MCP (1 μL L −1 ) overnight. All apples from both years were then held in ∼17 kPa O 2 + 4 kPa CO 2 , to mimic typical CO 2 build-up during commercial storage room loading, at 3 °C for up to 6 weeks. Overall, Summerland was more susceptible to external CO 2 injury than Pioneer ‘McIntosh’, developing notable symptoms after 4 weeks of storage. 1-MCP treatment increased the incidence of external CO 2 injury in ‘Empire’, regardless of cooling rate. However, 1-MCP-treated ‘Empire’ cooled rapidly developed less external CO 2 injury than those cooled slowly. Other fruit quality attributes (internal ethylene concentration, firmness, soluble solids concentration, and malic acid content) were only marginally affected by short-term holding in elevated CO 2 , in combination with cooling rate and/or 1-MCP treatment. These results suggest ‘McIntosh’ and ‘Empire’ apples are susceptible to developing external CO 2 injury without the establishment of low oxygen and typical controlled atmosphere (CA) storage. Furthermore, slow cooling after harvest may exacerbate the development of external CO 2 injury in apples during storage room loading. [ABSTRACT FROM AUTHOR]

Controlled atmosphere (CA) storage limits ethylene-related ripening of apple fruit, but can promote the development of CA-related injury. CA-related injury can be exacerbated by the ethylene antagonist, 1-methylcyclopropene (1-MCP). The main objective of this study was to investigate the impact of pre-storage conditioning, 1-MCP and elevated CO 2 on the development of CA-related injury and oxidative stress metabolites in ‘Honeycrisp’ ( Malus × domestica Borkh.) apple fruit. Upon harvest, fruit were treated with or without 1 μL L −1 1-MCP for 24 h, and then transferred to CA (2.5 kPa O 2 and 2.5 kPa or 0.03 kPa CO 2 ) at 3 °C (no conditioning) or conditioned at 10 °C for 5 d prior to CA. Apples were CA-stored for up to 35 weeks. CA-related injury occurred with storage under both CA regimes, regardless of 1-MCP and conditioning, whereas 1-MCP exacerbated the negative impact of elevated CO 2 on this disorder, approximating an 80% incidence, which was coincident with a 400% increase in γ-aminobutyrate (GABA). By comparison, pre-storage conditioning reduced the negative impact of 1-MCP on the incidence of CA-related injury at 2.5 kPa CO 2 by nearly 80%, and this was associated with a dramatically lower GABA concentration. Overall, rapid declines in total ascorbate and ascorbate/dehydroascorbate ratios were evident with storage, regardless of treatment. Transient declines in total glutathione and glutathione/glutathione disulphide ratios were more rapid and sustained for longer periods of time in conditioned than non-conditioned fruit. There were dramatic shifts in the levels of phosphorylated and non-phosphorylated pyridine dinucleotides with storage duration, regardless of treatment, resulting in elevated ratios of NADPH/NADP + and NADH/NAD + after 35 weeks, especially for conditioned fruit subjected to elevated CO 2 . Canonical powered partial least squares analysis revealed that metabolite profiles changed with storage period and treatment, and were most divergent during elevated CO 2 storage. Moreover, CA-related injury was strongly associated with changes in GABA, and moderately linked to total glutathione and glutathione redox status. [ABSTRACT FROM AUTHOR]

In combination with low temperature, controlled atmosphere storage and 1-methylcyclopropene (ethylene antagonist) application are used to delay senescence of many fruits and vegetables. Controlled atmosphere consists of low O 2 and elevated CO 2 . When sub-optimal partial pressures are used, these practices represent multiple abiotic stresses that can promote the development of physiological disorders in pome fruit, including flesh browning and cavities, although there is some evidence for genetic differences in susceptibility. In the absence of surface disorders, fruit with flesh injuries are not easily distinguished from asymptomatic fruit until these are consumed. Oxidative stress metabolites tend to accumulate ( e.g. , γ-aminobutyrate) or rapidly decline ( e.g. , ascorbate and glutathione) in vegetative tissues exposed to hypoxic and/or elevated CO 2 environments. Moreover, these phenomena can be associated with altered energy and redox status. Biochemical investigations of Arabidopsis and tomato plants with genetically-altered levels of enzymes associated with the γ-aminobutyrate shunt and the ascorbate–glutathione pathway indicate that these metabolic processes are functionally related and critical for dampening the oxidative burst in vegetative and fruit tissues, respectively. Here, we hypothesize that γ-aminobutyrate accumulation, as well energy and antioxidant depletion are associated with the development of physiological injury in pome fruit under multiple environmental stresses. An improved understanding of this relationship could assist in maintaining the quality of stored fruit. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of multiple 1-methylcyclopropene (1-MCP) treatments on fruit quality and disorder development in apples, with a second 1-MCP treatment applied after several months of controlled atmosphere (CA) storage. ‘McIntosh’, ‘Empire’, and ‘Northern Spy’ apples were harvested from commercial orchards and cooled overnight to 3 °C. 1-MCP (1 μL L −1 ) was applied 2 d after harvest and then again to half of the fruit after 4 months of CA storage. ‘Northern Spy’ apples also received a single 1-MCP treatment after 4 months of CA storage. Similar fruit from all cultivars were also not treated with 1-MCP. ‘McIntosh’ and ‘Empire’ were held at 3 °C and ‘Northern Spy’ at 0 °C for 9 months in CA storage (2.5 kPa O 2 + 2kPa CO 2 for ‘Empire’, 2.5 kPa CO 2 for ‘Northern Spy’, and 2.5 up to 4.5 kPa CO 2 for ‘McIntosh’). Overall, 1-MCP reduced internal ethylene production, and improved firmness and acidity retention in all apple cultivars. The addition of a second 1-MCP treatment after 4 months of CA storage further improved firmness retention in ‘McIntosh’ and late harvested ‘Empire’ apples after 7 d at room temperature. ‘Northern Spy’ apples treated with 1-MCP had lower incidence of external CO 2 injury, regardless of 1-MCP treatment timing. Multiple 1-MCP treatments had varying effects on the incidence of core browning; late-harvested ‘McIntosh’ treated twice with 1-MCP exhibited the highest incidence of core browning, while late-harvested ‘Empire’ treated twice had less core browning than those not treated. ‘Northern Spy’ treated only at harvest time had more core browning compared to those treated only or also after 4 months of CA storage and non-treated fruit. 1-MCP treatment had no significant effect on the incidence of internal browning in ‘McIntosh’ or ‘Empire’ apples. These results suggest that a second application of 1-MCP after 4 months of CA storage may improve firmness retention in some cultivars during holding at room temperature, but it can also have variable responses associated with susceptibility to disorders, especially when holding apples in long-term CA storage. [ABSTRACT FROM AUTHOR]