This study was conducted to investigate the effect of 1-methylcyclopropene (1-MCP) on fruit quality and incidence of physiological disorders for keeping freshness during marketing period in Asian pear (Pyrus pyrifolia Nakai) 'Wonhwang' and 'Whasan'. Fruits were treated with 1 μL･L -1 1-MCP for 12 hours at 25℃, at two or three stages of ripeness as determined by days after full bloom (DAFB). Fruits were harvested at 130 and 140 DAFB in early season cultivar 'Wonhwang' and 135, 145, and 150 DAFB in mid-season cultivar 'Whasan', respectively. Fruits were stored at 25℃ for 21 days and measured the flesh firmness, weight loss, soluble solids, acidity, ethylene, respiration and severity of physiological disorders at week interval. 1-MCP treatment to 'Wonhwang' pears harvested at 130 and 140 DAFB effectively delayed firmness loss during storage at 25℃. Untreated fruits of 'Wonhwang' pears harvested at 130 DAFB showed 32.3 and 10.1N of firmness after 14 and 21 days of shelf-life at 25℃, respectively, while those of the 1-MCP treated fruits showed 39.4 and 33.1N during same period. In the fruits harvested at 140 DAFB, the firmness of untreated fruit was lowered to 14.8 and 6.6N after 14 and 21 days, respectively, but those of 1-MCP treated fruit were 35.0 and 33.3N, respectively. Whereas, 1-MCP treatment delayed firmness loss only in the fruit harvested late (150 DAFB) in 'Whasan' pears. Higher soluble solids content and acidity during extended shelf-life were apparent in 1-MCP treated 'Wonhwang' pears, while those of 'Whasan' pears were little changed. 'Wonhwang' pears showed a relatively high ethylene production (maximum 0.58 μL･L -1 ) in the fruits harvested late than early harvested one. 'Whasan' pears showed little amount of ethylene production regardless of extended shelf-life. 1-MCP treatment to 'Wonhwang' pears decreased respiration rate following shelf-life, 42 and 50% reduction were observed at 14 days of shelf-life when compared with those of untreated ones harvested at 130 and 140 DAFB, respectively. No reduction of respiration rate by the treatment of 1-MCP was detected in 'Whasan' pears which showed considerably low respiration rate compared with 'Wonhwang' pears. Harvest time influenced the level of physiological disorders together with extension of shelf-life in both the cultivars. 1-MCP treatment completely blocked the incidence of internal browning of 'Wonhwang' pears harvested at 130 DAFB, and reduced the incidences of pithiness and core browning, while it promoted the flesh spot decay disorder regardless of harvest time. 1-MCP treatment was of little benefit for the prevention of physiological disorders in 'Whasan' pears compared with those of 'Wonhwang'.

We evaluated fruit quality and the incidence of physiological disorders in the Asian pear(Pyrus pyrifolia Nakai) cultivar 'Wonhwang' in response to 1-methylcyclopropene (1-MCP, 1.0 µL•L-1) treatment and different temperature conditions to determine its appropriate shelf-life period. Postharvest treatment with 1-MCP had a positive effect on 'Wonhwang' pears at all storage temperatures (18, 25, and 30°C) with regard to flesh firmness. Marketable fruits (>20 N) were only attainted using 1-MCP-treated fruit after 21 days of storage. A high incidence of physiological disorders and fruit decay was detected in fruits stored at 30°C, whereas a low incidence of physiological disorders including core browning, flesh browning, mealiness, and water soaking was detected in fruits treated with 1-MCP. Ethylene production and respiration rates increased with increasing temperature treatment. We detected high respiration rates in control fruits, reaching approximately two times higher than that of 1-MCP-treated fruits regardless of storage temperature. These results indicate that the efficacy of 1-MCP treatment on Asian pear depends on the storage temperature. Therefore, 1-MCP treatment should help maintain the quality of Asian pear fruits stored in high-temperature regions during the export process.

This study was conducted to investigate the effect of 1-methylcyclopropene (1-MCP), a known ethylene action inhibitor, on fruit quality and incidence of physiological disorders during simulated marketing period in Asian pears (Pyrus pyrifolia Nakai) of early-season cultivar 'Hanareum' and mid-season cultivar 'Manpungbae'. Flesh firmness was decreased abruptly at 15 days after shelf-life in untreated fruit of early-season cultivar 'Hanareum' which showed less than 19N, although those of 1-MCP-treated fruits were kept high value (>28N) during 15 days of shelflife. However, there were no distinct firmness changes during 30 days of shelf-life in mid-season cultivar 'Manpungbae' pear. Two pear cultivars did not show any considerable differences in quality indices such as soluble solids content, titratable acidity and skin color during the shelf-life regardless of 1-MCP treatment. The reduction of ethylene production level by 1-MCP treatment did not appeared in 'Hanareum' pear. Meanwhile, 1-MCP treated 'Hanareum' pears showed significantly low respiration rate during shelf-life. On the other hand, the inhibitory effect of 1-MCP was not remarkable in mid-season 'Manpungbae' pears. 1-MCP treatment completely blocked the incidence of physiological disorders including core browning and mealiness symptom during shelf-life only in early-season 'Hanareum' pears, and reduced considerably the pithiness disorder regardless of 1-MCP concentration. Consequently, we concluded that the treatment efficacy of 1-MCP is largely cultivar-dependent and the use of 1µL•L −1 1-MCP was recommended for the keeping quality and the prevention of physiological disorders only in early-season Asian pear 'Hanareum'.

We investigated the effect of postharvest treatments of calcium chloride, lysophosphatidyl ethanolamine (LPE) or 1-methylcyclopropene (1-MCP) on fruit quality during simulated marketing in Asian pear (Pyrus pyrifolia Nakai). 'Whangkeumbae' pear fruits were immersed in 0.25, 0.5 or 1.0% CaCl 2 solution with or without ultrasound (40kHz) at 25 o C for 3min followed by storage at 1 o C for 30 days simulated as abroad exportation. After simulated marketing at 25 o C and 80% relative humidity (RH) up for 10 days, quality parameters were evaluated. Results indicated that the ultrasound and CaCl 2 treatment had a synergic effect on keeping the green skin color which showed lower a* value. The combination treatment of ultrasound and 0.5% and 1.0% CaCl 2 significantly reduced internal browning disorders, although severe skin blemish disorder (20-23%) occurred in 1.0% CaCl 2 treatment. 'Wonhwang' pears were immersed in 1,000ppm LPE for 3 minutes or were fumigated in 1,000 ppb 1-MCP for 12 hours, respectively. The results of the fruit quality survey during the 21 days of distribution period are as follows. The 1-MCP treatment was maintained at a constant flesh firmness of 33N or higher during the distribution period. The LPE treated fruits had a lower physiological disorder index than the untreated group, but showed a relatively higher value than the 1-MCP treated group. In the case of 1-MCP treatment, the fruit respiration rate was significantly lower than of untreated control (6.0 mL•kg -1 •hr -1 ) during the simulaed marketing period. Consequently, it was expected that the postharvest treatments of 0.5% calcium chloride in pararell with ultrasound and 1-MCP fumigation can help to maintain Asian pear quality during distribution period.

Abstract:We investigated the effect of preharvest spray of aminoethoxyvinylglycine (AVG) on the fruit quality and incidence of physiological disorders during shelf-life of 'Hanareum' and 'Wonhwang' pear (Pyrus pyrifolia Nakai). AVG applications (0, 75, 150 and 300 mg･L -1 ) made 30 days before anticipated harvest of respective cultivar. AVG did not influence the fruit development and quality parameters including starch content, soluble solids and acidity at harvest time in two pear cultivars although the flesh firmness of the fruits treated with 300 mg･L -1 AVG were higher than that of control in 'Hanareum' pear. Among the three AVG concentrations, only 300 mg･L -1 AVG showed effectiveness on maintaining flesh firmness in 'Hanareum' pear during shelf-life. Meanwhile, competitive high flesh firmness was attained in 'Wonhwang' pear treated with 150 mg･L -1 AVG (27.7 N) and 300 mg･L -1 AVG (28.2 N) when compared with untreated control (17.8 N) during 21 days of shelf-life at 25°C. AVG did not cause any significant difference at skin color development relative to control in two pear cultivars. AVG decreased ethylene production and respiration rate at 300 mg･L -1 level in two pear cultivars during the entire shelf-life. During shelf-life, low incidence of physiological disorders including internal and core browning and mealiness were attained in the fruits treated at 300 mg･L -1 AVG in two cultivars when we compared with the untreated control.

In this study, we evaluated the differences in fruit development and quality indices of fruits subjected to blossom thinning before full bloom in 'Hanareum' and 'Niitaka' pears (Pyrus pyrifolia Nakai). We carried out a thinning treatments at 5 days before full bloom, targeting the blossoms at the 1st and 2nd position (T1) or the blossoms at the 6th and 7th position (T2) from the basal part of the flower cluster in both cultivars. Blossom thinning treatments increased the average fruit weight of early-season Asian pear 'Hanareum' up to 10.5% (T1) and 11.0% (T2) at harvest time (110 days after full bloom). The mid-season 'Niitaka' pear showed increased fruit weight of up to 12.6% (T1) and 16.8% (T2) at harvest time (170 days after full bloom). Moreover, these treatments increased the production rate of bigger sized fruits in both cultivars. Removal of blooms also affected fruit quality indices; the bloom-thinned fruits showed higher soluble solids contents (about 1 o Brix) and higher skin color redness (a*) especially in 'Niitaka' pears when compared to the non-thinned controls. Overall, the treatments increased the fruit size and weight as well as fruit quality including soluble solids and skin color. Bloom thinning treatment targeting the 6th to 7th blossom from the basal part of the flower cluster may be recommended as the practical thinning method in Asian pear 'Hanareum' and 'Niitaka'.Additional key words: fruit length, fruit diameter, skin color difference, soluble solids

We investigated the changes of fruit quality parameters, polysaccharide contents and cell wall components during maturation and ripening of two Korean pear cultivar 'Hanareum' and 'Manpungbae' compared with 'Niitaka' pear (Pyrus pyrifolia Nakai) which showed different physiological maturity based on days after full bloom (DAFB). Flesh firmness decreased continuously with fruit development and maturation, reaching a final level of 29.4, 33.5, and 27.4N at maturity in 'Hanareum' (127 DAFB), 'Manpungbae' (163 DAFB), and 'Niitaka' (170 DAFB), respectively. The level of ethylene production was very low in early season 'Hanareum' pear which showed at most 0.39 μL ‧ L -1 at maturity and no ethylene was detected in 'Manpungbae' and 'Niitaka' at maturity. Fructose was the most abundant soluble sugar during fruit maturation in the pears tested and an increase of sucrose was observed during fruit ripening in the Asian pears commonly. Ethanol insoluble solids (EIS) content decreased gradually with different levels among the pear cultivars as fruit ripens consisted of 10.79, 12.72, and 12.75 mg ‧ g -1 FW. The amount of total soluble polyuronides was higher in early season cultivars 'Hanareum' than those of mid-season cultivar 'Manpungbae' and 'Niitaka'. In 'Niitaka' which harvested most late season, the level of 4% KOH soluble hemicelluloses was lower than 'Hanareum' and 'Manpungbae' and maintained constantly during fruit ripening period. Cellulosic residues were determined high level in 'Niitaka' which showed 612.33 μg ‧ mg -1 EIS at maturity when compared with 'Hanareum' (408.0 μg ‧ mg -1 EIS) and 'Manpungbae' (538.67 μg ‧ mg -1 EIS). The main constituents of cell wall neutral sugars which consisted of arabinose, xylose, galactose, and glucose were decreased gradually with onset of fruit ripening regardless of cultivar. Arabinose which was predominant in 'Hanareum' pear decreased at the last stage of ripening, but the changes of cell wall neutral sugar during ripening were not occurred in 'Niitaka' pear. The change of molecular mass distribution in water soluble pectin observed dominantly at the early stage of fruit development. Depolymerization of 4% KOH-soluble hemicelluloses and degradation of xyloglucan showed in early-season cultivar 'Hanareum' during fruit maturation, and degradation of those fractions were detected only at the early stage fruit development in mid-season cultivar 'Manpungbae' and 'Niitaka'. The molecular mass profile of CDTA soluble pectin, Na2CO3-SP and 24% KOH soluble hemicelluloses showed no significant change during fruit maturation regardless of cultivar.

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