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Naju, South Korea

Choi J.-H.,Pear Experiment Station | Lee S.-H.,Chonnam National University
Journal of Applied Botany and Food Quality | Year: 2013

This study was conducted to microscopically verify the distribution and morphological changes occurring in stone cells during fruit growth in order to determine physiological changes occurring in stone cells in pear fruits. European pear (P. communis L. cv. 'Bartlett'), Chinese pear (P. bretschneideri Rehd. cv. 'Yali'), and Asian pear (P. pyrifolia Nakai cv. 'Niitaka') were collected from three trees of each cultivar for microscopic observation at 60 DAFB. Also, 'Niitaka' pear fruits were harvested at development stages of 30, 60, 90 and 150 DAFB. Stone cells were observed via light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The stone cells were found to be clustered less profoundly in the 'Niitaka' and 'Yali' pears than in 'Bartlett' pears, and the sizes of the clusters were smaller. Also, the stone cells were clustered closer to the epidermis in the 'Niitaka' and 'Yali' pears than in the Bartlett pears. Stone cells appeared in cluster structures beginning at 60 DAFB. The relative decrease in the quantity of stone cell clusters in the flesh was attributed to the fact that stone cells were no longer being generated, and the flesh cells increased dramatically in size. Developing and completed stone cells existed together within the same stone cell cluster. Source

Shin G.-H.,Jeollanam do Agricultural Research and Extension Services | Seo J.-B.,Jeollanam do Agricultural Research and Extension Services | Kim D.I.,Jeollanam do Agricultural Research and Extension Services | Seung-Koo Y.,Jeollanam do Agricultural Research and Extension Services | And 3 more authors.
Acta Horticulturae | Year: 2014

In the environment-friendly farming system, Fusarium wilt and crown brown rot occurred during the planting period and powdery mildew and gray mold during the harvesting. They have been causing serious damages at strawberry cultivation regions in Korea. Fusarium wilt caused by the soil-borne pathogen Fusarium oxysporum f. sp. fragariae Winks & Williams, was harmful at early growth stage of strawberry. Control of Fusarium wilt causing soil-borne disease was tried by soil drenching after addition of rice and wheat bran (1-2 t/10 a). The density of Fusarium wilt decreased and disease occurrence also decreased after strawberry plantation. Antagonistic microorganisms were tested with respect to the control of gray mold and powdery mildew on strawberry. Bacillus velezensis isolate successfully inhibited mycelium growth of gray mold. Liquid formulation of B. velezensis antagonist was treated three times (1/week) for three weeks on gray mold in the field, resulting in higher control efficacy (50.2%) than registered bio-pesticide. When B. velezensis antagonist was sprayed three times with 5-day intervals on powdery mildew in the field, the disease was successfully controlled with control efficacy of 88.7%. Source

Kim Y.K.,Pear Experiment Station | Kang S.S.,Pear Experiment Station | Cho K.S.,Pear Experiment Station | Hwang H.S.,Pear Experiment Station | And 2 more authors.
Acta Horticulturae | Year: 2011

Pear rootstocks affect the environmental adaptability as well as the nutritional status of the scion. In this research, we investigated the response of pear rootstocks to drought stress using polyethylene glycol (PEG) treatment to pear cultivars in vitro. Materials were obtained from the cultivars 'Chuhwangbae', 'Hwangkeumbae' (Pyrus pyrifolia Nakai), a Pyrus betulaefolia × Pyrus calleryana hybrid (PBPC), and open pollinated Oregon Pear Rootstock 195 (P. calleryana) (OPR195 OP) by shoot tip culture on MS medium supplemented with BA 1.0 mg/L and subjected to several concentrations of polyethylene glycol (PEG). In this experiment, PEG (0, 10, 15, 20, 25%, MW 6,000) inhibited shoot fresh weight and the total chlorophyll content of PBPC to the greatest extent at PEG 20% concentrations. Proline contents of PBPC and OPR195 OP were increased from 2.9 to 6.1 mg g -1 FW and from 6.2 to 10.8 mg g -1 FW, respectively, as PEG concentration increased. However, 'Chuhwangbae' and 'Hwangkeumbae' exhibited no increase in concentrations above 10 and 5%, respectively. Source

Yim S.H.,Pear Experiment Station | Kim Y.K.,Pear Experiment Station | Choi J.J.,Pear Experiment Station | Choi J.H.,Pear Experiment Station | And 3 more authors.
Acta Horticulturae | Year: 2015

Thinned pear fruit are thrown away as waste although they contain nutrients such as dietary fiber. For the investigation of possible use as functional materials, five Korean pear cultivars ('Chuwhangbae', 'Gamcheonbae', 'Manpungbae', 'Niitaka', 'Hanareum') were studied at unripe stage to determine the physicochemical properties and chemical compositions. The cultivars were picked at 30 days after full bloom, and all samples were analyzed for external and physicochemical properties. The size of the fruit from all five cultivars was compared, and it was determined that fruit from 'Gamcheonbae' and 'Manpungbae' were large, while fruit from 'Chuwhangbae' were small. The moisture content ranged from 71.5-75.0%, with those of 'Hanareum' being highest and 'Chuwhangbae' lowest. The contents of crude lipid (2.30-2.94%) and crude ash (4.57-4.89%) were significantly different among cultivars. Dietary fiber was 13.0-18.2%, significantly higher in 'Chuwhangbae'. The free sugar contents were 2.72-3.31% and were composed of sorbitol, fructose and glucose. Total phenolic and flavonoid content of 80% EtOH extract in 'Manpungbae' was higher than in other pears. Source

Choi J.H.,Pear Experiment Station | Kwon Y.H.,Pear Experiment Station | Choi J.J.,Pear Experiment Station | Yim S.H.,Pear Experiment Station | And 3 more authors.
Acta Horticulturae | Year: 2015

The present study was conducted to establish the proper harvest time of the Asian pear 'Manpungbae' through the changes in fruit quality at maturity and during storage. The peel of 'Manpungbae' fruit turned yellow, fruit increased in soluble solids concentration (SSC) as the harvest was delayed, however, firmness decreased and mealiness appeared after 170 days after full bloom (DAFB). The SSC increased but firmness did not change significantly during storage. Fruit SSC increased during storage of 5 weeks and fruit firmness decreased, however, the firmness remained higher than 12 N (N/5 mm ø) irrespective of harvest maturity. Considering fruit quality after storage, the proper harvest time was from 160 until 167 DAFB. The larger fruit (850 g) had a tendency to be higher in SSC than smaller fruit (550 g) at harvest and after storage. There was no difference in firmness between the larger and smaller fruit before storage. The firmness of smaller fruit did not change during storage, but for larger fruit it decreased by about 2.1 N. Source

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