• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.264-268
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• 2006

This study investigated the effect of self-incompatibility control substance 'Apple plus' in improving self-fertilization and quality on apple. Results showed that the rate of fruit setting of disc florets of Fuji apple in the open field increased from 17.2% in 2004 to 44.4% in 2005 for the treated plots and from 0.5% in 2004 to 3.0% in 2005 for the control. In the case of using net covering, the rate of fruit setting increased from 3.3% in 2004 to 5.2% in 2005 for the treated plots and from 0.4% in 2004 to 0.1% in 2005 for the control. For the quality of apple fruits, results showed that there was no significant difference on the fruit L/D and firmness for both control and treated plots. However, the number of seeds was affected by the different substances which produced the following average number of seeds: control, 0.9; IS-1, 1.2; IS-2, 1.2; IS-3, 1.5 and IS-4, 0.7. The SSR genetic analysis showed that the rate of self-fertilization was highest for IS-1 (100%), followed by IS-2 (73%), IS-3 (68%), IS-4 (62%) and control (0%).

• Horticultural Science & Technology
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• v.32 no.6
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• pp.912-916
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• 2014

Japanese apricot (Prunus mume Siebold and Zucc.) is a deciduous tree of the family Rosaceae, and it has long been used as a folk remedy for cough and dyspepsia. A new cultivar 'Okjoo' was developed from a cross between 'Gyokuei' and 'Rinsyu' carried out at the National Institute of Horticultural & Herbal Science in 1993. It w as s elected for good shape, large size and high yield capacity in 2006, and then it was granted official patent No. 4556 in 2013. It blooms 4 days and 2 days earlier than 'Gyokuei' and 'Rinsyu', respectively. Its flower petal color is pink, and the pollen amount is negligible. Its S-genotype, determined using Polymerase Chain Reaction with a S-RNase gene-specific primer pair, is $S_3S_6$. The average optimum harvest time of 'Okjoo' is late June. The fruit is round in shape and its suture is shallow. Average fruit weight is 18.5 g, and it contains total soluble solids $7.66^{\circ}Brix$ and titratable acidity at 4.81%. Fruit skin color is green. Sometimes only the light side of the fruits seems to develop blush. The incidence levels of scab (Cladosporium carpophilum Thumen) and bacterial shot hole (Xanthomonas arboricola pv. Pruni) are quite low. Consequently, 'Okjoo' seems to be a promising new cultivar for Japanese apricot growers.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.655-661
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• 2016

To develop scab-resistant pear (Pyrus spp.) varieties with fruits that are as crisp and juicy as Asian pears, a cross was made between 'Whangkeumbae' and 'Bartlett' varieties (P. pyrifolia ${\times}$ P. communis) at the Pear Research Institute of the National Institute of Horticultural & Herbal Science, Rural Development Administration, in 1994. Among the 285 seedlings, 'Greensis' was first selected in 2006 for its good eating quality and named in 2012 after regional adaptation tests in nine regions and ten experimental plots from 2007 to 2012. The tree showed a vigorous growth habit and semi-spreading characteristics, like 'Whangkeumbae'. The optimum fruit harvest date was also around Sept. 26 and fruit was round in shape and green in skin color at maturity. Average fruit weight was 470g, and the soluble solids content was $12.4^{\circ}Brix$. The flesh was very crisp and juicy, and had good eating quality. Its' leaf size was similar with 'Bartlett' and smaller than 'Whangkeumbae'. The average of full bloom date of 'Greensis' was determined as Apr. 26, which was six days later than 'Whangkeumbae' and similar with 'Bartlett'. S genotypes of 'Greensis' were identified as $S_4S_e$ by S-allele PCR product sequencing analysis. It seems that the $S_4$ allele was inherited from 'Whangkeumbae' and the Se allele from 'Bartlett'. 'Greensis' displayed strong resistance to scab disease caused by Venturia nashicola, similar to European pear cultivars like 'Beurre Hardy' and, 'Conference'. 'Greensis' was also highly resistant to black leaf spot (Alternaria kikuchiana) in the field

• Horticultural Science & Technology
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• v.34 no.6
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• pp.959-965
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• 2016

In 1994, a new cultivar 'Joyskin' was created from a cross between the cultivars 'Whangkeumbae' and 'Waseaka' at the Pear Research Institute of the National Institute of Horticultural and Herbal Science, Rural Development Administration. In 2006, the 'Joyskin' was selected from among the 317 seedlings resulting from the cross for its skin and taste qualities. Regional adaptation tests were conducted in nine regions and in ten experimental plots from 2006 to 2011. The cultivar was named in 2011. 'Joyskin' showed a vigorous growth habit and semi-spread characteristics similar to 'Whangkeumbae'. The average full bloom date for 'Joyskin' was April 21st, which was also similar to 'Whangkeumbae'. The optimum fruit ripening time was September 6-8th, which was six or eight days earlier than 'Whangkeumbae'. The fruit was round in shape and the skin was a golden yellow color at maturity. The average fruit weight was 320 g and the flesh firmness was $2.5kg/8mm{\varphi}$. The firmness of the fruit skin determined by a blade-type plunger of texture analyzer was 22.9 N, which was significantly different from that of 'Whangkeumbae' 29.9N. Stone cell analysis of 'Joyskin' by phloroglucinol-HCl, showed that 'Joyskin' stone cells were small in size and few in numbers cpmpared to those of cultivars of was 'Manpungbae', 'Niitaka', and 'Whangkeumbae'. The patent application for 'Joyskin' was submitted in April, 2012 (Grant No. 2012-337). In 2016, 'Joyskin' (Grant No. 5895) was registered as a separate record, with uniformity and stability per Korean Seed Industry Law.