• Horticultural Science & Technology
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• v.34 no.3
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• pp.453-460
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• 2016

The parentage of the horticulturally important pear cultivar 'Niitaka' was confirmed by determining its S-genotypes based on the S-RNase and $PpSFBB^{-{\gamma}}$ genes, and genotyping using simple sequence repeat (SSR) markers. Previous reports suggested that the cultivars 'Amanogawa' and 'Imamuraaki' were the parents of 'Niitaka', although the cultivars 'Chojuro' and 'Shinchu' were also examined as candidate parents, along with two other cultivars. In the present study, the S-genotype of 'Niitaka' was determined to be $S^3S^9$. The $S^9$-RNase of 'Niitaka' was found to be likely inherited from the parent 'Amanogawa' ($S^1S^9$) and the $S^3$-RNase from 'Chojuro' ($S^3S^5$) or 'Shinchu' ($S^3S^5$). Based on the S-genotypes, the cultivar 'Imamuraaki' ($S^1S^6$) had no contribution to the parentage of 'Niitaka' ($S^3S^9$). A total of 67 polymorphic SSR markers were used to further confirm the parentage of 'Niitaka'. Discrepancies were found at several SSR loci between 'Niitaka' and the cultivars 'Imamuraaki' and 'Shinchu', whereas 'Niitaka' inherited alleles from 'Amanogawa' and 'Chojuro' at all SSR loci. Therefore, our findings established that 'Amanogawa' and 'Chojuro' are the parents of pear cultivar 'Niitaka', and not 'Imamuraaki' as previously reported.

• The Journal of Natural Sciences
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• v.10 no.1
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• pp.57-61
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• 1998

Postharvest dipping of vacuum infiltration treatments of 'Chojuro' pear fruit in $CaCl_2$ resulted in increased calcium content, especially in fruit peel and outer flesh such as just below peel. As $CaCl_2$ concentrations increaced from 2% to 8% in dipping treatment, calcium content became higher. But vacuum infiltration under 200-600 mmHg did not affect and dipping and vaccum infiltration did not have any difference in fruit calcium content. Decreasing of fruit firmness determined at 4 weeks during storage was slower in fruits with $CaCl_2$ treatment than control.

• 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.

• Korean Journal Plant Pathology
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• v.10 no.3
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• pp.169-174
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• 1994

A new unidentified pear leaf spot disease presumed to first occur in the late 1970's has recently become prevalent over the pear growing areas, and caused the greatest problem for pear production in Korea. The disease began to develop on pear leaves at mid- to late May, peaked at mid- to late une, but stopped further development until September in cool climate. Leaf lesions are 0.9∼2.5 mm in diam., oval or irregular to rectangular in shape, first appeared reddish purple, later changed to dark brown, and to whitish grey in the late season. Lesions were limited to appear only on the mature, hardened leaves, initially from leaf margin or near the leaf veins, and later scattered over the leaf surface. Individual lesions usually did not enlarge, but often coalesced each other, commonly causing shot holes and eventual early falling. The disease was most severe on the major pear cultivars Niitaka and Okusankichi ranged with 4 to 100% infections in trees, depending on the orchards, but not on the cultivar Chojuro. Damages from the disease included lower fruit weight, and higher acid and less sugar content in fruits, resulting in lowering the overall fruit quality. Etiology of the disease including identification of the causal organism is in a separate paper.

• The Journal of Natural Sciences
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• v.8 no.2
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• pp.175-179
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• 1996

The fruit soluble solids and acidity decreased during storage regardless of fruit size, fruit firmness decreased also, and the decreasing rate of the firmness in large fruit was higher than small. The ethylene production of fruit was increased during storage, and there was the peak of fruit respiration rate at 2 and 6 weeks after harvest. The calcium and magnesium content was the highest in peel, the lowest in flesh, and intermediate in core. Especially, the calcium content in the outer flesh was lower than in the inner flesh, and the magnesium content in the middle part of flesh was lower than in the other parts. The Ca/Mg ratio in the inner flesh and the K/Ca ratio in the outer flesh were higher than in the other parts.

• Horticultural Science & Technology
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• v.19 no.1
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• pp.60-65
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• 2001

'Shinil' pear cultivar (Pyrus pyrifolia Nakai) which was originated in a cross between 'Shinko' (non-patented, released in 1941) and 'Hosui' (non-patented, released in 1972) in 1978 was released as a middle season harvest variety. Its usual picking time coincided with 'Chuseok' season which is one of the most famous national holiday in Korea. The fruit showed high soluble solids content and good appearance. The cultivar was preliminarily selected in 1991, and its regional adaptability was evaluated in the name of 'Wonkyo Na-13' at 9 sites for four years from 1992, and finally selected and named in 1995. 'Shinil' is medium in tree vigor like 'Hosui' and spreading in tree habit as 'Niitaka', a leading cultivar in Korea, and consistently very productive. It has high resistance to black rot caused by Alternaria kikuchiana and pear necrotic spot caused by pear necrotic spot virus. Its full bloom is one day earlier than that of 'Niitaka' cultivar and harvest time is September 25 at Suwon area which is 3 days later than that of 'Hosui'. Fruit is round in shape with a deep medium stalk cavity and medium calyx basin and has attractive light yellow brown skin color. The fruit weight ranges between 300 and 400 g, which is similar to 'Chojuro', 'Shinko', and 'Hosui'. Soluble solid content is approximately at the level of 13-14 Brix, which is higher than that of 'Chojuro'. The flesh is cream-white, very juicy, and light grit with soft and fine texture.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.645-650
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• 2011

Pear cultivar 'Supergold' (Pyrus pyrifolia var. culta Nakai) was originated from the cross between 'Chuwhangbae' and 'Manpungbae' with the aims of improving the fruit quality of 'Chuwhangbae' cultivar at Pear Research Station of National Institute of Horticultural & Herbal Science, Rural Development Administration in 1994. 'Supergold' was preliminarily selected in 2002 and named in 2008. The tree shows a vigorous growth habit and semi-spread characters like as 'Manpungbae'. Furthermore, it has sufficient flowers and carries abundant pollen grains, so it can also be used as a pollinator. 'Supergold' is highly resistant to black leaf spot (Alternaria kikuchiana) in the field condition. The optimum harvest time is around Sep. 11th, which is ahead of 'Whangkeumbae' about 5 days in the harvest period. The fruit shape is oblate and fruit skin color is greenish-white at harvesting time. The average weight of fruit is 570 g, and the soluble solids content is $13.6\;^{\circ}Brix$. The flesh is very soft and juicy, and renders good eating quality. Shelf life is about 6 months under the cold storage condition. To determine the self-incompatibility (SI) genotype of 'Supergold' pear cultivar, it was crossed with other cultivars of which SI genotypes have already known. The result of cross-pollinations of 'Supergold' with other cultivars showed relatively high rates of fruit set from 64.5% to 91.0%, except for the cross with pollens of 'Nijisseiki' that represented only 28.8% of fruiting rate. Although sometimes the stigma of 'Supergold' crossed with 'Hayatama', 'Chojuro', and 'Nijisseiki' showed malformed pollen tube tips, 'Supergold' is generally supposed to have cross-compatibility with all other pollen donor cultivars. It is considered that the S-allele of 'Supergold' is $S_3S_4$, which is based on the result of PCR-RFLP.

• Horticultural Science & Technology
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• v.19 no.1
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• pp.66-70
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• 2001

'Mansoo' is a late-season pear cultivar with extra large and high quality fruit of long storability, which was released by National Horticultural Research Institute in 1995. The cultivar originated from the cross between 'Danbae' and 'Okusankichi' at Suwon in 1978, had been under regional adaptability test at nine areas in the name of 'Wonkyo Na-15' for 4 years since 1992. It was vigorous in tree growth and upright in tree shape. Its flower bud is easily maintained, resulting in higher productivity than 'Danbae' and 'Okusankichi'. It bloomed a day later than 'Niitaka', and showed cross-compatibility with 'Niitaka', 'Chojuro' and some other varieties. Harvesting time of 'Mansoo' is late October in Suwon. The fruit shape is oblate and skin color is light yellowish brown. The fruit weighed 600-700 g and has 12-13% soluble solids content. The flesh is soft, juicy, and has negligible grit. It is resistant to black leaf rot (Alternaria kikuchiana Tanaka).