Behrouz Ehsani-Moghaddam

Timing of postharvest 1-methylcyclopropene treatment affects Bartlett pear quality after storage

DeEll, J. R. and Ehsani-Moghaddam, B. 2011. Timing of postharvest 1-methylcyclopropene treatment affects Bartlett pear quality after storage. Can. J. Plant Sci. 91: 853-858. This study investigated the effects of postharvest 1-methylcyclopropene (1-MCP) treatment timing on the ripening and physiological disorders of Bartlett pears during cold storage and subsequent shelf-life. Pears were held for 1, 3 or 7 d at 3°C after harvest and then treated with 0.3 µL L-1 1-MCP for 24 h at 3°C. Fruit quality attributes were evaluated after 4 mo of cold storage at 0.5°C, plus 1 to 11 d at 22°C. All 1-MCP treatments reduced ethylene production, as well as delayed fruit softening and yellow color development. However, the most substantial benefit of 1-MCP observed was the marked reduction in disorders, especially senescent scald and internal breakdown. The results suggest that 1-MCP treatment 3 d after harvest provided the best balance of reduced disorder development during storage and the ability of Bartlett pears to soften adequately thereafter. Fruit treated with 1-MCP at 1 d after harvest did not soften as much as those treated 3 or 7 d after harvest, while treatment after 7 d provided less control of disorders than treatment after 1 or 3 d.

Antioxidant capacity in June-bearing and day-neutral strawberry

The present study was carried out to estimate the crude, hydrophilic and lipophilic antioxidant content of known and new advanced selections among June-bearing and day-neutral genotypes using Trolox equivalent antioxidant capacity method. Crude, hydrophilic and lipophilic extractions were prepared using 25 g of frozen fruits from each sample. In June-bearing strawberries, significant differences were observed among crude, hydrophilic and lipophilic antioxidant values of different selected genotypes. Mean of crude, hydrophilic and lipophilic antioxidants in June-bearings were estimated to be 20.4, 13.4 and 0.5 μmol TE g-1 FW, respectively, which were higher than those of the day-neutral genotypes (i.e., 13.2, 9.4 and 0.3 μmol TE g-1 FW). The present study revealed the importance of genetic background for determining the antioxidant potential in selected June-bearing genotypes and the possibility of production of new strawberry cultivars with higher levels of antioxidant capacity through breeding programs. ...

1-Methylcyclopropene treatment modifies postharvest behavior of Fantasia nectarines

The effects of 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action, on the ripening and quality of Fantasia nectarines were examined. Fruit were harvested from two commercial orchards and subsequently exposed to 1 μL L-1 of 1-MCP for 24 h at 0°C. Following treatment, fruit were held at 0°C for 0, 2, or 4 wk, and then assessed for quality during a ripening period at 23°C. 1-MCP treatment improved postharvest firmness retention in nectarines after 0 and 2 wk at 0°C plus 4 days at 23°C. Soluble solids concentration (SSC) was lower in nectarines treated with 1 MCP and held for 0 or 4 wk at 0°C, compared with similar non-treated fruit. The peel ground color change from green to yellow was also delayed by 1-MCP. Nectarines treated with 1-MCP exhibited less CO2 and hydrophobic volatile production during 14 days at 23°C, compared with non-treated fruit. The overall inhibition of fruit ripening by 1-MCP appears transitory in Fantasia nectarines. Chilling injury was observed after 4 wk of storage at 0°C a...

Regulation of superoxide dismutase isoforms in resistant and susceptible strawberry cultivars subjected to leaf spot disease

Abstract Macroscopic symptoms were observed in two strawberry cultivars, with the degree of symptom intensity varying depending on the susceptibility of the cultivars, i.e. resistant or susceptible. The symptoms presented as red spots and were observed 30 d following leaf tissue inoculation with the Mycosphaerella fragariae pathogen. A comparison of the superoxide dismutase isoform profiles obtained by gel electrophoresis in all samples extracted from both resistant and susceptible cultivars indicated one constant sharp band, identified as Mn[sbnd]SOD with a molecular mass of 19 kDa. The intensity of this band was higher in all samples derived from the resistant cultivar than in those from the susceptible cultivar. Another superoxide dismutase (SOD) isoform, identified as CuZn[sbnd]SOD with a molecular mass of 16 kDa, was detected in all soluble proteins derived from the resistant cultivar. This isoform was not observed in the susceptible cultivar; however, following an incremental increase in the amount of loaded protein, it was illuminated as a faint band in a sample collected 3 d after inoculation, indicating insufficient production of the CuZn[sbnd]SOD isoform in the susceptible cultivar during an oxidative burst induced by the M. fragaria pathogen. Several bands were also characterized in both cultivars containing Fe and Mn as their co-factors (Fe, Mn[sbnd]SOD). Unlike in the resistant cultivar, where the activity of Fe, Mn[sbnd]SOD isoforms gradually and regularly increased and reached its highest level on the third day after inoculation, the activity of the isoforms changed irregularly over 20 days of study in the susceptible cultivar.

Effects of delayed controlled atmosphere storage on disorder development in ‘Honeycrisp’ apples

Abstract: The objective of this study was to investigate the effects of delayed controlled atmosphere (CA) storage on fruit quality and disorders in temperature conditioned ‘Honeycrisp’ apples. For three consecutive years, ‘Honeycrisp’apples were harvested from the same commercial orchard and conditioned for 4 d at 12-19 °C immediately after harvest. Apples were then held in ambient air at 3 °C for 0, 2, 4, 8, or 14 wk, followed by CA storage (3 kPa O2 and 1.5 kPa CO2) at 3 °C for 6 or 7 mo of total storage time. The effect of 1-methylcyclopropene (1-MCP; 1 µL L-1) was also investigated. Delaying the establishment of CA reduced the incidence of internal CO2 injury, with or without flesh cavitation. Furthermore, higher incidence of CO2 injury required longer delay of CA to reduce the disorder. In some years, delayed CA also resulted in increased lenticel breakdown, bitter pit/blotch and greasiness. 1-MCP treatment reduced lenticel breakdown when CA establishment was delayed 4 wk or more. There was variation in fruit firmness among years and durations of CA delay, and some increase in firmness was observed during storage. 1-MCP-treated fruit showed little change in firmness with delayed CA. There was also little effect of delayed CA on internal ethylene concentration (IEC), soluble solids concentration (SSC), and malic acid content. These results suggest that conditioning and delaying CA storage reduces the incidence of internal CO2 injuries in ‘Honeycrisp’ apples, but the delay may aggravate other disorders.