• Journal of Environmental Science International
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• v.23 no.12
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• pp.2129-2134
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• 2014

The antioxidant activities and total phenolics of four Rosaceae species Pourthiaea villosa (Thunb.) Decne, Sorbus commixta Hedlund, Sorbaria sorbifolia var. stellipila Maxim and Pyrus pyrifolia (Burm.f.) Nakai were determined. Phenolic content (polyphenol and flavonoid), radical scavenging activities [2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylnezthiazoline-6-sulfoic acid) (ABTS)] and ferrous ion chelating effect were evaluated. Total polyphenol and flavonoid contents were highest in Pourthiaea villosa (Thunb.) Decne and lowest in Pyrus pyrifolia (Burm.f.) Nakai. Phenolic contents of Pourthiaea villosa (Thunb.) Decne was $331.45{\pm}7.78$ and $90.4{\pm}3.5mg{\cdot}g^{-1}$. DPPH and ABTS radical scavenging activities were found to be lowest in Sorbus commixta Hedlund whereas Sorbaria sorbifolia var. stellipila Maxim and Pourthiaea villosa (Thunb.) Decne showed relatively good DPPH and ABTS radical scavenging activities. Ferrous ion chelating effect was highest in Pyrus pyrifolia (Burm.f.) Nakai ($1.05{\pm}0.04mg{\cdot}ml^{-1}$) and lowest in Sorbus commixta Hundlund ($4.22{\pm}0.71mg{\cdot}ml^{-1}$).

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.1
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• pp.87-94
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• 2016

Skin damage is mainly caused by environmental factors such as ultraviolet light, heat, and smoking. It is known that reactive oxygen species production is commonly involved in the pathogenesis of skin damage induced by these factors, causing skin aging. Pyrus pyrifolia Nakai continues to be a popular and highly consumed fruit in many countries with known beneficial effects including antitumor, antioxidative, and anti-inflammatory effects. However, there is no evidence of a therapeutic effect of Pyrus pyrifolia extract (PPE) against skin aging via inhibition of mitochondria-mediated apoptosis. In this study, we investigated PPE protective effect against photoaging induced by UVB ($50mJ/cm^2$) in HS68 human dermal fibroblasts. Lactate dehydrogenase assay showed that PPE significantly protected HS68 cells against UVB-induced damage in a dose-dependent manner. Other assays using DCF-DA demonstrated that PPE protected HS68 cells by regulating reactive oxygen species production. PPE also regulated mitochondrial dysfunction and mitochondrial membrane potential induced by UVB, and inhibited UVB-induced caspase-3 activity. These results indicate that PPE protects human dermal fibroblasts from UVB-induced damage by regulating the oxidative defense system.

• Korean Journal of Food Science and Technology
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• v.47 no.2
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• pp.170-175
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• 2015

The methanol extract of Asian pear (Pyrus pyrifolia N. cv. Chuhwangbae) fruit peel was purified using solvent fractionation, Sephadex LH-20 column chromatography, and octadecylsilane high performance liquid chromatography. Based on the electrospray ionization mass spectrometry and nuclear magnetic resonance data, the two isolated compounds were identified as quercetin 3-O-${\beta}$-D-glucopyranoside (1) and 3,5,6,7,8,3',4'-heptahydroxyflavan [(-)-dulcisflavan, 2]. Compounds 1 and 2 were isolated and identified for the first time from Asian pears and pears, respectively.

• Journal of Plant Biotechnology
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• v.40 no.4
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• pp.203-209
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• 2013

Genetic manipulation of pear (Pyrus pyrifolia Nakai) breeding is still difficult due to lack of reliable regeneration system. The aim of this research is to establish shoot regeneration system from leaf explants for pear (P. pyrifolia cv. Niitaka) using various concentrations of plant growth regulators and carbon source supplemented to medium. The highest regeneration rate of about 20% was found on a medium containing 4.4 g/L of Murashige and Skoog (MS) without vitamins, Linsmaier and Skoog (LS) vitamins were added separately. Leaf explants of pear were cultured on MS medium containing 7 g/L of Daishin agar supplemented with various concentrations of NAA (0.01, 0.05, 0.1, 0.5 mg/L) in combination with BA(3, 5, 10 mg/L) for shoot regeneration. In medium with 5 mg/L of BA and 0.01 mg/L of NAA, adventitious shoot regeneration rate was higher than others treated. The optimal results were observed using MS medium supplemented with 30 g/L sorbitol as carbon source on regeneration system. Sorbitol is considered better carbon source than sucrose for shoot regeneration of pear (P. pyrifolia cv. Niitaka). In order to increase of shoot regeneration in pear (P. pyrifolia cv. Niitaka), plant agar and Daishin agar used as gelling agents, Daishin agar is more efficient in shoot regeneration.

• Korean Journal of Agricultural Science
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• v.44 no.1
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• pp.23-29
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• 2017

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' (126 g/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.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.174-179
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• 2013

Three low-molecular compounds were isolated from methanol extracts of pear (Pyrus pyrifolia N. cv. Chuhwangbae) fruit peels using solvent fractionation, various types of column chromatogrphy (Diaion HP-20, Sephadex LH-20, and silica gel), and high performance liquid chromatography with an assay guided by 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity. The isolated compounds were identified as 2-carboxyl-4(1H)-quinolinone (kynurenic acid, 1) from butanol fraction, cis-p-coumaric acid (2) from ethyl acetate-acidic fraction, and vanillin (3) from the ethyl acetate-phenolic fraction, respectively. These isolated compounds were confirmed on the basis of the spectroscopic data of electrospray ionization mass spectrometry and nuclear magnetic resonance. This is the first time that compounds 1-3 were isolated and identified in pear.

• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.64-71
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• 2017

The study was performed on the effects of crop load of pear (Pyrus pyrifolia Nakai) trees on shoot growth, reserved nutrients, and fruit production for two years, as well as regrowth of cuttings treated with various cold temperatures in 2012 and 2013. Crop load adjustments included three levels of fruiting; 54 (60%), 90 (100%), and 126 fruits per tree (140%). As increasing crop load from 60% to 140%, water sprout growth decreased, and one-year old shoot resulted in declined concentrations of total carbon, macro-nutrients, and free sugar. The 140% of crop load greatly increased fruit yield of approximately 35 tons per ha in both 2011 and 2012 but slightly reduced weight, size, and soluble solid contents in fruit. However, 140% of crop load increased annual production income to approximately over 10 million won compared to the 60% and 100% of crop load. Germination rates in the cuttings did not rapidly decrease up to $-20^{\circ}C$ in a growth chamber condition. The 140% of crop load decreased germination rates less than 70% of cuttings grown under $-30^{\circ}C$. Amounts of electrolyte leakage in the cuttings under various cold temperatures were not significantly different among the adjustment of crop load.

• Korean Journal of Plant Resources
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• v.37 no.1
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• pp.62-70
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• 2024

Fruit thinning rate and characteristics were investigated for three years on seven promising pear (Pyrus pyrifolia Nakai) cultivars, which were treated by lime-sulfur as an eco-chemical thinning substance. Lime-sulfur was treated twice at the second and third days after full bloom by cultivar. Most of pear cultivars were significantly thinned by lime-sulfur compounds. Especially 'Whangkeumbae', 'Supergold' and 'Hanareum' exhibited high flower thinning rates, 41.5%, 40.1% and 39.9%, respectively. As weather conditions at the lime-sulfur treatment, insolation and cloud amount were correlated with flower thinning rate but not significant (r = 0.49 and r = -0.45, respectively). These results suggest that lime-sulfur is suitable for reducing labor force for flower thinning of Korean pears but flower thinning effects of lime-sulfur can vary depending on other factors such as environmental conditions. This information will provide useful data for low labor force cultivation of Korean pear cultivars.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.759-771
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• 2016

We compared the fruit set and the quality of the 'Niitaka' pear (Pyrus pyrifolia Nakai) among flowers pollinated by two bee species (Apis mellifera and Bombus terrestris) and pollinated artificial. The artificial pollination rate was 1.3 to 1.9 times higher than the bee pollination rate. Moreover, the artificially pollinated flowers produced fruit that was 5 to 10% higher in weight, 2 to 3% larger in size, and had a higher fruit shape index (L/D) than fruit pollinated by the bees. On economic analysis, net profit from insect pollinator was 93.5 to 97.1% of net profit from artificial pollination. Therefore, artificial pollination is more efficient than bee pollination in 'Niitaka' pear. However, regarding fruit quality and net profit, these results suggest that bee pollination can be an good alternative to artificial pollination in 'Niitaka' pear.

• Journal of Bio-Environment Control
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• v.11 no.1
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• pp.1-4
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• 2002

The occurrence rate of russet in 'Whangkeumbae' pear showed significant difference by years because the russet occurrence is greatly affected by the amount of rainfall. This study was conducted to analyse the relationship between rainfall and russet occurrence by artificial treatment of high humidity. Under high relative humidity condition, stomatal resistance decreased and average fruit weight was higher since the increased net photosynthesis rate accumulation accelerated fruit growth. The russet occurrence began on July 25, when the growth speed of fruit weight and fruit surface is the most fast. Russet occurrence rate was higher in high relative humidity condition because the fruit growth was accelerated. Since the fruit calcium concentration change is extreme in late July, it is assumed that the deceased calcium content is related to the occurrence of russet in 'Whangkeumbae' pear, When the high relative humidity condition is maintained after rainfall, the amount of net photosynthesis rate increase and fruit growth is accelerated. Therefore, the unbalance in the amounts of transferred photosynthesis assimilation product, water and mineral elements would be one of the reasons for the russet occurrence in 'Whangkeumbae' pear.