This study was evaluated on time of occurrence and tissue characteristics in fruit cracking of mid-season cultivar Whansan Asian pears (Pyrus pyrifolia Nakai) with high amount of precipitation from 60 to 120 days after full bloom (DAFB). Fruit cracking was observed at different topographic ‘Whansan’ pear orchards as a pre-experiment. Pear trees at mountainous orchards received low amount of precipitation in June, between 50 and 80 DAFB, and had a high defoliation and low average of fruit weight and fruit cracking (2.5%) compared to those of pears grown at plain and middle-mountainous orchards. In a main experiment, cracked fruit contained lower concentrations of Ca and higher water soluble pectin in flesh or peel than those of values observed on the intact fruit. Fruit diameter rapidly increased at 40 DAFB and mostly 70–80 DAFB under repeated fluctuation of soil water potential between − 28 and − 67 kPa. Fruit were early completed their cell division and converted into cell enlargement phase between 30 and 50 DAFB, advancing formation of cork cells, while the number of large stone clusters significantly increased at 50 DAFB. Besides of less Ca uptake, both formation of cork and stone cells reduced cell flexibility in the flesh, causing initiation of internal micro-cracking under repetition of rapid change of soil water potential. Fruit cracking was visually progressed at 75 DAFB when fruit were mostly enlarged.

This study was conducted to determine the optimal physiological ripening time and suggest a reasonable harvest time indicator by analyzing the relationship between change in physicochemical characteristics and the sugar composition change patterns during development of 'Hanareum' fruit from 54 days after full bloom (DAFB) to 130 DAFB. The weight of fruits from 96 to 115 DAFB rapidly increased and then became gentle showing a typical sigmoidal curve. Flesh hardness decreased steadily after 96 DAFB; there was no significant difference in flesh hardness for 115, 125 and 130 DAFB fruits. The starch content began to reduce around the core for 119 DAFB. Moreover, sucrose and fructose contents started to increase with fruit development; however, the sucrose content continuously increased, whereas the fructose content started to decrease for 110 DAFB. Fruits of 125 and 130 DAFB did not show coloration according to the iodine test. Based on these results, it was estimated that the optimal physiological ripening time of 'Hanareum' was between 119 and 125 DAFB. The results of correlation analysis between fruit development change and sugar composition change patterns of fruits of 'Hanareum' showed that there was a strong linear relationship. Correlation coefficient between the sucrose/fructose (S/F) ratio and flesh hardness is -0.57, between S/F ratio and iodine test results is 0.80. Namely, S/F ratio is possible to use for harvest time determination indicator and the point of S/F ratio of 0.9–1.1 was considered to be ideal for the determination of the optimal physiological ripening time at which starch completely degrades.

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.

'황금배'에서 염화칼슘 침지 처리에 따른 유통 중 품질을 조사한 결과, 0.5% 염화칼슘 처리구가 20.5-21.3N으로 다소 높게 유지되었다. 과피색의 변화에 있어 적색도인 $a^*$ 은 무처리구는 -2.62로 가장 높았고, 염화칼슘+초음파 처리구가 -3.03~-4.13으로 가장 낮아 과피의 녹색소실이 지연되었다. 유통환경에서 가장 ...

Interspecific hybridization is a popular breeding method employed to introduce effective factors into crops. To evaluate the potential of this method to enrich the quality of pear fruits, we carried out crosses between P. pyrifolia and other species using the pollens of 'OPR114' and 'OPR260' of P. betulaefolia, 'Dangshansuli' , 'Xuehuali ' , and 'Yali' of P. bretschneideri, 'OPR125 ' , 'OPR195 ' , and 'OPR249' of P. calleryana, 'Bartlett', `Bose', 'Canal pear', and 'Max Red Bartlett' of P. communis, and 'Chuhwangbae' of P. pyrifolia to pollinate flowers of P. pyrifolia 'Niitaka'. Fruit set in 'Niitaka' pear after artificial pollination was investigated under both field and controlled conditions, which encompassed temperature control and use of water-cuttings of winter twigs. To assess compatibility of hybridizations, pollen tube elongation was analyzed in squashed styles under controlled temperature, and the self-incompatibility (SI) gene pattern was validated by PCR. Under field conditions, crosses of 'Niitaka' with 'OPR114' of P. betulaefolia and `Bose' and 'Canal pear' of P. communis resulted in incompatibility, as the fruit set was low. However, when 'Niitaka' was pollinated by 'Xuehuali', some of the pollen tubes reached the ovary but they then arrested and appeared swollen in the middle part of the style. PCR confirmed the incompatibility of these crosses, as the gene product from pollens was a different size from that of the 'Niitaka'. However, interspecific hybridization under controlled conditions resulted in fruit production. We show that interspecific hybridization with P. pyrifolia and other species was feasible under controlled conditions. Suggesting that self-incompatibility of crosses was dependent on environmental factors rather than genetic predisposition.

We examined the effects of pre-drying rates, delayed cooling, and carbon dioxide (CO2) treatment on skin blackening, a major physiological disorder during cold storage in Asian pear (Pyrus pyrifolia Nakai) ‘Chuhwangbae’. Total skin blackening incidence was calculated as the percent disorder index (PDI). PDI significantly decreased with increasing pre-drying rate: the highest PDI was 37.3 for the 1% pre-drying treatment and the lowest PDI was 5.1 for the 4% treatment. Meanwhile, the 5% pre-drying treatment did not show a statistically significant difference from the 4% treatment. A 48-h cooling delay at 20°C was the most effective treatment for preventing skin blackening. PDI after cold storage at 1°C was 6.2, 9.2, and 19.1 for 48-h delay, 24-h delay, and no delay, respectively. In the CO2 treatment, 2% CO2-treated fruit showed rapid disorder symptoms from eight days after cold storage at 1°C, and the PDI increased to 19.6 at 12 days and to 63.2 at 20, which was three times higher than the untreated fruits. A decrease in total phenolic content appeared more pronounced in the tissues treated with 2% CO2, while polyphenol oxidase (PPO) activity in untreated fruits increased with increasing skin blackening incidence. However, there was no increase in PPO activity with the 2% CO2 treatment, skin blackening appeared to be a CO2 injury rather than enzymatic oxidation. Additional key words: CO2 injury, peroxidase, polyphenol oxidase, pre-conditioning, storage

본 연구에서는 동양배 ‘진황’의 1-MCP처리 후 유통온 도에 따른 과실의 품질 변화를 관찰하였다. 과실의 감모 율의 경우 저장온도가 낮을수록 적었으며 1-MCP처리구 가 무처리구 보다 유의하게 적은 감모를 보였다. 수확 후 1-MCP처리는 과육경도에서 유통온도(18, 25 및 30°C)와 관계없이 20N이상으로 무처리구보다 높게 유지 되었다. 과피색의 변화는 모든 처리구에서 저장기간이 길어질수록 어두워졌으며, a*값은 18 및 25°C에서는 처 리구간 차이를 보이지 않았지만, 30°C에서는 1-MCP처 리구가 유의하게 적은 변화를 보였다. 과실의 생리장해 에서 과심갈변, 분질과 발생은 저장온도가 낮을수록 발 생이 적었으며, 1-MCP 처리구가 무처리구 보다 낮은 발 생을 보였다. ‘진황’과실에서 1-MCP처리후 유통온도에 따른 과실의 품위유지 기간은 18 및 25°C에서는 28일 내외이며, 30°C에서는 21일 내외로 1-MCP 처리로 유통 기간을 약 7일 이상의 품위유지에 효과를 보였다. 이러 한 결과는 특히 고온의 시장조건에서는 조생종 ‘진황’ 과실에 1-MCP처리가 품위유지에 효과적인 것으로 사료 된다.

In this study, we evaluated the changes of fruit quality indices during fruit development and ripening in Korean new pear cultivar ‘Changjo’, developed from a cross between ‘Tama’ and ‘81-1-27’ (‘Danbae’ × ‘Okusankichi’) in 1995 and named in 2009, to determine appropriate harvest time and to enhance the market quality and broaden the cultivation area. The fruits of ‘Changjo’ pears harvested from 132 days after full bloom (DAFB) to 160 DAFB. Fruit growth and quality indices were monitored at 1 week interval by measuring fruit weight, length, diameter, firmness, and taste related quality indices. The calculated fruit fresh weight increased continuously with fruit development and reached to an average of 594g on Sep. 20 (160 DAFB). The ratio of length to diameter declines as fruit maturation progress, resulting in 0.898 for ripe fruit stage as a round oblate shape. Flesh firmness of ‘Changjo’ pears showed over 30N until 153 DAFB and then decreased abruptly with fruit ripening, reaching a final level of about 26.44N on 160 DAFB. Starch content of fruit sap was also decreased abruptly after 146 DAFB which decreased almost half of the fruits harvested at 139 DAFB. In parallel with the decrease of flesh firmness, ethanol insoluble solids (EIS) content decreased sharply with fruit ripens, only 50% of EIS was detected on the fruits harvested on 160 DAFB when compared to that of the fruits harvested on 139 DAFB (Aug. 30). The maximum value of soluble solids contents was observed in the fruits harvested on 153 DAFB, resulting in 14.2Brix. The changes of skin color difference a* which means loss of green color occurred only after 139 DAFB, coincide with the decrease of SPAD value of the fruit skin. The sugars of the 80% ethanol soluble fraction consisted mainly of fructose, sorbitol, glucose and sucrose, also increased during maturation and ripening. Fructose and sucrose contents were larger than those of glucose and sorbitol in flesh tissues. These results were explained that stored starch is converted to soluble sugars during fruit maturation, mainly in fructose and sucrose increasing the sweetness of this cultivar. Total polyphenols were increased up to middle of fruit maturation (146 DAFB) and then decreased continuously until the end of fruit maturation. Consequently, our results suggested that the commercial harvest time of ‘Changjo’ pears should not be passed 153 DAFB and late harvest of this cultivar would not good for quality maintenance during shelf-life. As a result of the post-harvest low-temperature acclimation experiment during the short-term transportation period, fruits harvested at 146 DAFB tended to maintain higher firmness after 14 days of simulated marketing at 25C compared to fruits harvested at 153 DAFB regardless of temperature set. And, the slower the rate of decrease to the final transport temperature of 5C, the higher the incidence of internal browning and ethylene production. Therefore, in order to suppress the physiological disorder and to maintain the fruit quality when exporting to Southeast Asia in the ‘Chanjo’ pears, it is desirable to lower the temperature of the fruits within a short time after harvest and to set the harvest time before 146 days after full bloom. Additional key words : ethylene, firmness, respiration, ripening, soluble solids *Corresponding author: jpchun@cnu.ac.kr *Received June 02, 2017; Revised September 13, 2017; *Accepted October 12, 2017 이욱용 · 최진호 · 안영직 · 천종필 379 Protected Horticulture and Plant Factory, Vol. 26, No. 4, 2017 서 론 배 ‘창조’는 국립원예특작과학원에서 1995년 ‘수진조 생’에 ‘81-1-27’을 교배하여 2009년에 최종 선발한 품종 으로 검은무늬병에 저항성이며 성숙과의 과중은 700g 내외, 당도는 13Brix로 식미가 매우 우수하다. 평균 숙 기는 10월 2일(수원지방 기준)로 ‘신고’ 보다 10일 정도 빨라 추석이 조기에 도래할 때 유통이 가능하다는 점에 서 유망 품종으로 대두되고 있다(Shin 등, 2011). 과실의 성숙시기 즉 수확 시기는 유통 중 품질유지 및 생리장해 발생에 결정적인 영향을 미친다. Jeong 등 (1998)과 Hong 등(2004)은 품종과 과실의 성숙도에 따 라 호흡 특성이 달라지고 호흡 특성과 관계없이 미숙기 에 수확한 과실이 상온에서 보관된 것보다 저온 및 CA 조건에서 더 오래 저장되므로 각 품종별 수확시기 및 보관방법을 결정하는 것이 매우 중요하다고 하였다(Kim 등, 2002; Kim 등, 2003; Kim 등, 2007). 배 과실의 수 확시기 결정 요인에는 과피색의 변화, 과육 경도, 호흡 량 등의 지표를 이용할 수 있으며 적정한 시기에 수확 한 과실은 상온, 또는 고온 유통 중 급격한 품질 악화를 줄일 수 있는 것으로 보고된 바 있다(Lee와 Chun, 2011; Lee 등, 2011; Oanh 등, 2012). 그러나, 최근 농 가에 보급 중인 ‘창조’ 품종은 성숙생리 및 수확 후 생 리 변화에 대한 보고가 없다. 온도는 원예산물의 수확 후 품질변화를 좌우하는 주요 요인이다(Brosnan과 Sun, 2001), 즉, 온도는 수확 후 과 실의 품질 변화 항목 중 과실의 호흡량과 밀접한 관련 이 있다. 품온이 높은 상태에서 수확된 과실의 온도관리 는 상품성 유지에 매우 중요한 요소이다(Bachmann과 Earles, 2000). 사과에 있어서는 지연냉각을 통해서 장기 저장 한 사과의 생리장해 경감 효과가 보고된 바 있다 (DeLong 등, 2004). 동양배에 있어서도 유통 온도에 따 른 호흡량 및 에틸렌 생합성과 같은 생리적 변화가 다 르게 나타나므로(Lee 등, 2017), 과실품질의 변화를 늦 추기 위해서는 수확 이후 저온조건에서 과실의 호흡량을 낮추는 조치가 필요하다(Oh 등, 2010). 이에 본 실험은 ‘창조’ (‘수진조생’ × ‘81-1-27’) 배의 성숙 및 연화생리를 이해하는 기초자료로 제공하고 단기 수출과정에서의 과실 품질 변화를 지연 시킬 수 있는 수송온도 설정 방법을 연구하여 고품질 국내 육성 배의 생산 및 수출물량 확대에 기여하고자 실시하였다.

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) 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. OPEN ACCESS Received:

This study was conducted to investigate the effect of 1-methylcyclopropene(1-MCP), an inhibitor of ethylene action, on fruit quality and incidence of physiological disorders during simulated marketing period in early-season Asian pear(Pyrus pyrifolia Nakai) ‘Noksu’. Flesh firmness was decreased abruptly at 15 days after shelf-life in control fruits. which showed less than 10.7N, although those of 1-MCP-treated fruits were kept high value(>30.4N) during 20 days of shelf-life. ‘Noksu’ pears did not show any considerable differences in quality indices such as soluble solids content, titratable acidity during the shelf-life regardless of 1-MCP treatment. The reduction of ethylene production level by 1-MCP treatment did not appeared in ‘Noksu’ pear. Meanwhile, 1-MCP treated ‘Noksu’ pears showed significantly low respiration rate during shelf-life. Also, 1-MCP treatment blocked the incidence of physiological disorders including core browning, internal browning, water soaking and mealiness symptom during shelf-life. Consequently, we concluded that the 1-MCP treatment effectively inhibited the incidence of physiological disorders and extended the shelf-life for 10 days in early-season Asian pear ‘Noksu’.

국내에서 육성된 중생종 동양배 품종인 ‘창조’는 성숙 기간 중 지속적으로 과실이 비대하여 600g대의 편원형 과실로 발달하였다. 성숙기간 중 경도는 경시적으로 저 하되어 만개 후 153일인 9월 13일에 32.58N으로 조사 되었고 만개 후 160일에는 26.44N으로 급격히 경도가 저하되었다. 식감과 관련된 품질요인 중 과실의 전분함 량은 만개 후 153일에 0.737, 만개 후 160일에 0.451로 전분함량이 급속히 감소하였고, 과육의 세포벽함량을 조 사하였던 결과, 과실비대가 증가하고 과실성숙의 진행과 더불어 알코올불용성물질 함량은 낮아지는 경향을 보였 다. 과피색차 중 적색도(a*)는 만개 후 139일 이후 양의 값을 보여 외관상의 과피녹색 발현이 소실되었는데 과피 의 SPAD 값을 조사한 결과에서도 동일하게 엽록소의 감소를 확인할 수 있었다. Hue angle 역시 성숙과 연화 기간 중 유의하게 감소하는 경향을 보여 수확시기의 지 표로 활용 가능하다고 판단되었다. 성숙기간 중 과육 내 에 축적되는 당 성분을 분석한 결과, 만개 후 153일에 총량이 최대치를 보였는데 전 생육시기에 걸쳐 전체 당 성분 중 과당이 우점하고 있었고, 과실성숙도가 높아질 수록 자당의 비율이 유의하게 증가하여 만개 후 160일 에 수확한 과실에서는 자당이 과당을 넘어 우점하여 과 숙단계로 생각되었다. 따라서, 배 신품종 ‘창조’의 적정 수확시기는 만개 후 153일인 9월 13일 이전으로 평가되 었고 수확시기를 놓친 경우에는 경도 등 과실의 품질이 급격하게 하락하는 것으로 사료되었다. 대만 지역 수출 을 모의하여 단기수송온도 설정을 위한 수확 후 저온순 화 실험을 실시한 결과, 만개 후 146일에 수확한 과실이 만개 후 153일에 수확한 과실에 비하여 25°C 유통 후 높은 경도를 유지하는 경향을 보였고 최종 수송 목표 온도인 5°C로 저하되는 속도가 느릴수록 과육장해의 발 생심도 및 에틸렌발생량이 높은 경향을 보였으므로 ‘창 조’ 품종에 있어 동남아 지역 수출 시 생리장해 및 과실 품질 유지를 위해서는 수확시기를 만개 후 146일 이전 에 설정하는 것이 바람직할 것으로 판단되었다. 본 연구 결과를 바탕으로 ‘창조’ 배의 목적별 수확시기 결정 및 과실의 선별 기술에 일조하고 수출 시장에서의 한국산 배의 신인도 확보에 기여할 것으로 기대된다.

This study was conducted to explore which pollen type could be an effective pollen source for self-incompatible ‘Niitaka’ pear (Pyrus pyrifolia Nakai), when different pollinizers were to be applied. The pollens of five different pears with similar flowering times were applied to bagged ‘Niitaka’ flowers grown in Cheonan city, Korea. Pollen types used were of different origins including Korean pears (‘Wonhwang’ and ‘Chuhwangbae’), Japanese pears (‘Chojuuro’ and ‘Okusankichi’), and Chinese pear (‘Yali’). Results show that the amount of pollen produced by flowers of each cultivar was the largest in Korean pear ‘Wonhwang’ (234 g/100 flowers) and the smallest in Japanese pear ‘Okusankichi’ (126g/100 flowers). A high proportion of large fruits (> 600 g), 71.4% of total production, was found in the fruits treated with ‘Yali’ pollen. However, these fruits showed an unfavorable external appearance. Based on individual fruit width differences, ‘Chojuuro’ treatment produced the smallest difference in fruit diameters (3.2 mm) and ‘Yali’ treatment’ gave the largest (4.8 mm). Also, the difference in fruit length was the largest in ‘Yali’ (7.5 mm), which also produced the most uneven fruits among the pollinizers used. Meanwhile, the use of pollens of ‘Wonhwang’ and ‘Chuhwangbae’ improved productivity by increasing the fruit shape index and the ratio of bigger fruits in total production. Moreover, those pollens also decreased the development of lenticels on fruit skins which gave them a smoother appearance.

The purpose of this study was to establish postharvest management techniques including a temperature pre-conditioning protocol for maintaining fruit quality in newly developed early season Korean pear cultivar 'Hanareum' (Pyrus pyrifolia Nakai). The fruits were treated with three different pre-conditioning temperatures (21, 25, or 29 degrees C) for 4 days according to the harvest time (103 or 110 days after full bloom, DAFB). The percent weight loss was relatively low in the fruits subjected to low pre-conditioning temperature regardless of harvest time. The firmness of the fruits treated with pre-conditioning at 21 degrees C remained high during 20 days of simulated marketing at 25 degrees C, although all treated fruits showed a general decline of firmness with extended time of simulated marketing. These fruits also showed higher appearance and a lower incidence of mealiness disorder symptoms. During the experimental periods, the production of ethylene was lower in the fruits pre-conditioned at 21 degrees C in comparison with those of treated at 25 and 29 degrees C. High respiration rates were obvious in the fruits pre-conditioned at high temperature (29 degrees C), especially in the optimum-harvested fruits, where respiration was approximately two times higher than that of fruits exposed to 21 degrees C during pre-conditioning. However, the respiration rate was similar during simulated marketing at 25 degrees C regardless of harvest time. These results demonstrated that temperature pre-conditioning at 21 degrees C is a simple and effective postharvest technique for summer harvested Korean pear cultivars including 'Hanareum'.

The purpose of this study was to establish postharvest management techniques including a temperature pre-conditioning protocol for maintaining fruit quality in newly developed earlyseason Korean pear cultivar ‘Hanareum’ (Pyrus pyrifolia Nakai). The fruits were treated with three different pre-conditioning temperatures (21, 25, or 29°C) for 4 days according to the harvest time (103 or 110 days after full bloom, DAFB). The percent weight loss was relatively low in the fruits subjected to low pre-conditioning temperature regardless of harvest time. The firmness of the fruits treated with pre-conditioning at 21°C remained high during 20 days of simulated marketing at 25°C, although all treated fruits showed a general decline of firmness with extended time of simulated marketing. These fruits also showed higher appearance and a lower incidence of mealiness disorder symptoms. During the experimental periods, the production of ethylene was lower in the fruits pre-conditioned at 21°C in comparison with those of treated at 25 and 29°C. High respiration rates were obvious in the fruits pre-conditioned at high temperature (29°C), especially in the optimum-harvested fruits, where respiration was approximately two times higher than that of fruits exposed to 21°C during pre-conditioning. However, the respiration rate was similar during simulated marketing at 25°C regardless of harvest time. These results demonstrated that temperature pre-conditioning at 21°C is a simple and effective postharvest technique for summer harvested Korean pear cultivars including ‘Hanareum’.