• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.3
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• pp.172-181
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• 2020

Koshihikari has been one of the most popular rice cultivars with good eating quality since the 1960s despite its susceptibility to blast disease and lodging. To map the genes controlling blast resistance and to develop promising blast-resistant breeding lines inheriting Koshihikari's high eating quality, a recombinant inbred line (RIL) population was developed from a cross between Koshihikari and a blast resistance donor with early maturity, Baegilmi. A total of 394 Koshihikari × Baegilmi RILs (KBRIL), and the two parents, were evaluated for blast resistance and major agronomic traits including heading date, culm length, panicle length, and tiller number. A linkage map encompassing 1,272.7 cM was constructed from a subset of the KBRIL (n = 142) using 130 single nucleotide polymorphisms. Two quantitative trait loci (QTL) for blast resistance, qBL1.1 harboring Pish/Pi35 and qBL2.1 harboring Pib, were mapped onto chromosomes 1 and 2, respectively. qBL1.1 was detected in both of the experimental sites, Namwon and Jeonju, while qBL2.1 was only detected in Namwon. qBL1.1 and qBL2.1 did not affect agronomic traits, including heading date, culm length, panicle length, and tiller number. From the 394 KBRILs, lines that were phenotypically similar to Koshihikari were selected according to heading date and culm length and were further divided into the following two groups based on blast resistance: Koshishikari-type blast resistant lines (KR, n = 15) and Koshishikari-type blast susceptible lines (KS, n = 15). Although no significant differences were observed in the major agronomic traits between the two groups, the KR group produced a greater mean head rice ratio than the KS group. The present study provides useful materials for developing blast-resistant cultivars that inherit both Koshihikari's high eating quality and Baegilmi's blast resistance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.185-192
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• 2019

Early-maturing rice type is cultivated to produce rice before the Korean Thanksgiving Day. We investigated the flowering and ripening characteristics of major breeding lines in early maturing rice type. In Jeonju, field growth days (FGD) from transplanting to heading changed about 3.3 days by 10 days of transplanting days and about 2.5 days by the change of mean temperature during growth period. As the temperature during ripening stage, 1000 brown rice weight was changed 0.2 g, the rice quality of brown and milled rice was changed 5% and 6.5%, respectively. Baegilmi and Kittake showed early heading habit suitable for harvesting before Korean Thanksgiving. Joun and Pecos showed good ripening characteristics under high temperature during the ripening stage. We expect that these characteristics might be useful for breeding new rice cultivars for harvesting before Korean Thanksgiving.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.3
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• pp.190-200
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• 2021

The heading response of rice varieties, originated from South Korea, North Korea, and northern China, was examined under the temperature and day-length conditions of 10 low-temperature regions in North Korea. When 30-day-old broadcast tray-raised seedlings (BS) were used, only one or a few varieties reached the heading stage within the safe marginal heading date (SMHD) under the Hamhung, Pyonggang, Huichon, and Kanggye conditions. In the Yangdok and Sinpo environments, no varieties reached heading until SMHD. The South Korean varieties that reached the heading stage between SMHD and late marginal heading date (LMHD) were Jinbuol, Baegilmi, Joun, Jopum, Jinok, Jopyeong, Sanhomi, and Odae for the Hamhung, Pyonggang, Huichon, and Kanggye; Joun for Sinpo; and none for Yangdok, Kimchaek, Sonbong, and Chunggang environments. The number of days to heading (DTH) was positively correlated among all 10 regions. Reduced DTH in the 30-day-old pot tray-raised seedlings (PS), compared to BS, was not consistent with varieties and regions. Reduced DTH in PS, compared to BS, was the largest in Jinok and Sonbong9 among the South and North Korean varieties, respectively, whereas it was small in the northern Chinese varieties. The South Korean varieties that headed until SMHD in PS were Jinok for the Hamhung, Pyonggang, Yangdok, Sinpo, and Kanggye environments; and Jinbuol, Jopum, and Jinok for the Huichon condition. In the Kimchaek and Chunggang conditions, Jinok reached the heading stage within LMHD. With the use of PS for some responsive varieties such as Jinok, varietal adaptability could be improved to the conditions of low-temperature regions in North Korea. None of the PS or BS among the tested varieties reached the heading stage until LMHD for the Chongjin and Sonbong conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.3
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• pp.106-113
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• 2023

We examined the heading responses of rice varieties over two years in Dandong, China to select the varieties that are adaptable to the bordering northwestern plains of North Korea. Dandong had slightly lower mean temperature than Sinuiju, North Korea but slightly higher than Supung, but it had almost the same day-length as the two regions in North Korea. In the two experimental years and two transplanting-date treatments, eight varieties (Jinbuol, Baegilmi, Joun, Jinok, Jopyeong, Jinbu, Sanhomi, and Odae) from South Korea and five varieties (Olbyeo2, Sonbong9, Onpo1, Gilju1, and Pyongdo5) from North Korea reached the heading stage not later than the latest heading dates of Dandong domestic varieties and the safe marginal heading dates of Dandong. We examined the basic vegetative phase (BVP), photoperiod-sensitivity (PS), and thermo-sensitivity (TS) of rice heading in a phytotron study to characterize the heading ecotypes of rice varieties adaptable to Dandong. For the rice varieties grown in Dandong experimental field, number of days to the heading stage was highly positively correlated with PS and, except middle and mid-late maturing three varieties, it was significantly positively correlated with BVP. Two-dimensional distribution plotting revealed that both 35 days or less BVP and 25 days or less PS were the characteristic heading ecotypes of the rice varieties adaptable to Dandong.