• Korean Journal of Food Science and Technology
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• v.48 no.1
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• pp.59-65
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• 2016

This study was carried out to investigate the total polyphenols, antioxidant activities, and melanin synthesis inhibition of several pear cultivars (Pyruspyrifolia). The total polypenolic content of five pear cultivars was high in the unripe developmental stage. Total polyphenolic content of the Chuwhangbae cultivar extract was higher than that of other pear cultivars regardless of the developmental stage. However, the total flavonoid content did not differ between cultivars or developmental stages. The phenolic compound, arbutin has an inhibitory effect on melanogenesis. Arbutin levels in pear cultivars declined as the fruit matured. The free radical scavenging activity of the extract also decreased as the fruit ripened. In B16F10 mouse melanoma cells, most of the cultivar extracts inhibited melanin synthesis by about 50% at a $100{\mu}g{\cdot}mL^{-1}$ concentration, except in the Gamcheonbae extract until 90 days after full bloom. We have confirmed that the extract of pear cultivars have antioxidant activity and skin-whitening effects.

• Food Science and Preservation
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• v.20 no.2
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• pp.222-226
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• 2013

This study was performed to confirm physiological activities according to parts of new pear cultivars (Gamcheonbae, Manpungbae, Chuwhangbae, Hanareum) and Niitaka pear. The total polyphenol compound contents of pear peel, flesh and core were 178~235, 95~113, 177~229 mg/100 g as tannic acid equivalent, respectively. There were differences in the contents by cultivars, Chuwhangbae and Hanareum cultivars showed high contents. The total flavonoid contents of the pear peel, flesh and core were 29.2~40.2, 24.3~34.3, 26.9~38.8 mg/100 g, respectively and those of Chuwhangbae and Gamcheonbae cultivars showed comparatively high values. The electron-donating ability was high in Chuwhangbae, Gamcheonbae and in the pear peel (29.7~57.7%), core (29.1~38.2%), flesh (7.6~17.7%), in that order. The nitrate scavenging activity was highest in that pear peel (21.0~49.8%), followed by the core (11.8~16.2%) and flesh (7.8~9.7%), but there was little difference by cultivar.

• The Plant Pathology Journal
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• v.39 no.2
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• pp.228-233
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• 2023

Two pear cultivars with different degrees of resistance to Venturia nashicola were evaluated on the basis of a disease severity rating for pear scab resistance under controlled environmental condition. Two inoculation techniques were tested: the procedure for inoculation by dropping conidia suspension of V. nashicola; the procedure by deposition of agar plug on the abaxial surface of pear leaves. All tested cultivars resulted in blight symptoms on the inoculated leaves and became spread to uninoculated region or other leaves. Although both methods provide satisfactory infection of V. nashicola on pear leaves, the mycelial plug method of inoculation was more reliable than the spray inoculation method for the evaluation of pear scab disease resistance. The incubation period of V. nashicola in the resistant pear cultivar, Greensis was longer than that in the susceptible cultivar, Hwasan.

• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.210-216
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• 1995

Alternaria spp.were predominantly isolated from the abnormal leaf spot lesions of pear cultivars Niitaka and Nijiiseiki. Alternaria isolates from the cultivar Niitaka were not pathogenic to both cultivars, but the isolates from the cultivar Nijiiseiki developed typical lesions of black leaf spots and were identified as A. kikuchiana. However, no typical abnormal leaf spot lesions were produced by the Alternaria isolates. Foliar spray of twelve different agrochemicals including lime sulfur, either alone or in combinations, with 7 times applications from April to July failed to reduced the disease development. Application of 17 different pesticides including fungicides, insecticides and herbicides currently used in pear orchards did not cause leaf injury similar to the abnormal leaf spot. Simulated acid rain of as low as pH 3.0 did not incite any leaf lesions alike the abnormal spot lesions. Mineral contents in the leaves of both cultivars did not differ significantly between the healthy leaves and those with abnormal leaf spots. When cuttings of pear tree were obtained in February from newly emerged twigs of the healthy or the diseased trees of Niitaka and planted in sand in the greenhouse, only those from the diseased trees developed typical leaf lesions of the abnormal spot. These results indicate that abnormal leaf spots are caused by unknown systemic agents in pear trees, rather than by Alternaria spp., chemical injury or acid rain.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.35-35
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• 2022

Pears (Pyrus spp.) have been grown worldwide as a kind of important economical fruits. Over 1,500 accessions collected from countries have been preserved in National Institute of Horticultural and Herbal Science, Rural Development Administration in Korea. However, redundancies and misidentification are happening in the germplasm preservation due to same cultivars which have different names in various localities (synonyms) and different cultivars which have same names (homonyms). That can lower germplasm management efficiency. The object of this study is to identify synonyms and homonyms in pear germplasms by analyzing genetic variation with four microsatellite markers: CH03d12, CH03g07, CH02b10, and EMPc117. PCR amplification with above 4 microsatellite markers was done for the 31 pear accessions, and the products were analyzed by agarose gel electrophoresis. As a result, 7 synonyms and 9 homonyms were identified among 31 pear accessions. We'll compare these genotypes with phenotypes of each pear accessions, and reduces the redundancy and misidentification in pear germplasm collection for the reliable management.

• Horticultural Science & Technology
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• v.19 no.1
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• pp.43-47
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• 2001

This study was conducted to investigate the integrated control strategy against pear black leaf spot disease. Using indicator plant PS-95 we selected six virus-free trees (cv. Niitaka) from commercial orchards in the major pear production area. Disease symptom by pear black leaf spot in the shoot of pear (Niitaka) has been successfully inhibited by heat treatments for 3 weeks at temperature of $40^{\circ}C$ (day) and $32^{\circ}C$ (night) or 4 weeks at $37^{\circ}C$ and $30^{\circ}C$, respectively. However, survival rate of the shoot tips on stocks was low. Seven cultivars Niitaka, Imamura- aki, Waseaka, Nijisseiki, Wasenijisseiki, Shinsetsu and Whangkeumbae produced visible symptoms in the first year after inoculation with the virus. Other 11 selections remained symptomless. Two resistant cultivars Suwhangbae and Gamcheonbae were selected, which showed high fruit quality. It is recommended that these cultivars could be top-grafted onto the infected Niitaka trees to overcome the damage caused by the disease in the orchard.

• Korean Journal of Agricultural Science
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• v.15 no.1
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• pp.1-7
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• 1988

Out of 24 isolates of Alternaria collected from pear leaves, only 7 isolates from cv. Nijiseiki leaves were specifically pathogenic to susceptible pear cultivar(Nijiseiki). Other isolates from cv. Chojuro, Oksankichi and Sinko did not show any pathogenicity to pear leaves. Pathogenic isolates of Alternaria kikuchiana produced host-specific toxin (AK-toxin) in liquid culture which caused veinal necrosis only on susceptible pear leaves, while nonpathogenic isolates did not produce this toxin. Varietal susceptibility among pear cultivars to the pathogen was investigated by evaluating HST (AK-toxin) sensitivity of pear leaves, as a substitute for spore inoculation. AK-toxin which the fungus produces was toxic to pear cultivars susceptible to the pathogen such as Isipsegi and Sinsu, but was harmless to resistant pear cultivars such as Chojuro, Oksankichi, Niitaka etc. Changes in disease susceptibility and toxin sensitivity of pear leaves with aging was investigated. Disease susceptibility and toxin sensitivity in cv. Sinsu leaves appeared to vary with leaf aging; the young leaves were visibly susceptible, but older leaves (more than 2 week old leaves) became resistant.

• Journal of Applied Biological Chemistry
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• v.59 no.4
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• pp.337-343
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• 2016

The Asian pear (Pyrus pyrifolia Nakai) has historically been one of the most popular fruits in Korea because of its sweetness and juiciness. Nowadays, 81.5 % pears of the 'Niitaka' cultivar are grown in Korea, and most of these are consumed as table fruits. Due to the increase in consumer demand for novel Asian pear varieties, developing new cultivars is of great commercial interest. Since 1984, 'Niitaka' cultivar has been introduced in Korea and 13.3 % was developed into new cultivars in the last 20 years alone. Recently, the consumption rate of fresh Asian pears has been limited. The demand for pears, especially the 'Niitaka' cultivar has no longer increased. As a result, new cultivars of Asian pears have been introduced and their properties have been investigated. This review article provides an overview of the physicochemical characteristics and antioxidant activities of new cultivars of Asian pears.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.63-63
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• 2022

Pear (Pyrus spp.) is a typical fruit and grown in the temperate climate regions throughout the world. Development of appropriate methods for in vitro propagation and root induction are important to increase the production rate and plant quality rapidly. This study was conducted to find the most appropriate media conditions for in vitro propagation and rooting of three pear cultivars, 'Barttlett', 'BaeYun No.3' and 'Oharabeni'. In vitro propagation was induced on Murashige and Skoog medium (MS) with 2.0 mg/L N6-benzyladenine (BA) and 0.2 mg/L indole-3-butyric acid (IBA) medium. For root induction of these cultivars, the shoot explants of the propagated plants were cultured on two different media containing 1/2 MS medium containing 0.2 mg/L IBA with 15 g/L Sucrose (Rooting Medium 1, RM1) and 1/4 Linsmaier and Skoog medium (LS) medium containing 1 mg/L IBA and 1 mg/L NAA hormone with 7.5 g/L glucose (Rooting Medium, RM2) and after 2 weeks, the plants on the RM2 medium are transferred on RM1 medium (RM2 condition). After nearly seven weeks, percentage of rooting formation were 22.2% in RM1 and 30% in RM2 conditions for Barttlett and 70% in RM1 and 60% in RM2 conditions for Oharabeni cultivars. No differences in these cultivars were observed between RM1 and RM2 conditions. However, BaeYun No.3 cultivar was observed 0% in RM1 and 72.7% in RM2 conditions. This study will help to propagation and root induction of in vitro plants for various pear cultivars.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.1
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• pp.51-58
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• 2014

Freezing hardiness of winter bud and branch of several pear (Pyrus pyrifolia) cultivars according to degree and duration of low temperatures was investigated by sprouting, electrolyte leaching rate and triphenyltetrazolium chloride (TTC). Sprouting rate as infected by degree and duration of low temperature were different between cultivars. The lower temperature, the longer duration, sprouting rate was decreased. Electrolyte leaching rate was showed above 30% at below $-30^{\circ}C$ treatment regardless of cultivars and duration. The lower temperature and the longer duration, Electrolyte leaching rate was increased. Electrolyte leaching rates of Manpungbae, Niitaka and Chuwhangbae at $-30^{\circ}C$ for 9 hours treatment which were observed high sprouting rate, were lower than those of other varieties. Absorbance rates by TTC test at $-21^{\circ}C$ treatment were 66.0 to 96.5% for 6 hours, 49.4 to 91.9% for 9 hours, and 37.3 to 89.4% for 12 hours. Freezing hardiness of pear cultivars at ecodormancy was different according to degree and duration of low temperature treatments.