• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.199-214
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• 1977

These studies were conducted to obtain basic information of the rice blast resistance in comparision with blast occurrence patterns in the blast nursery test in Korea. One hupdred and twenty nine rice varieties including several blast differential varieties and 30 combinations of pedigree lines were tested at six different locations, Suweon, Chulweon, Chuncheon, Iri, Jinan, Imsil, and Milyang, in 1976~1977. The results obtained are summarized as follows: 1. When blast resistance was tested using three sets of differential varieties at six locations, prevalent races were different depending on the location and differential variety set tested. 2. There were regional differences in blast disease reation among Japonica rice varieties and among Indica${\times}$Japonica crosses. 3. At Suweon blast disease reactions of pedigree lines were different from that at Imsil. 4. Three varietal groups were made depending on the develpment of rice blast in the nursery test. 5. In general, highly resistant varieties to rice leaf blast were also resistant to neck blast, but there were exceptions.

• Research in Plant Disease
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• v.21 no.1
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• pp.20-23
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• 2015

A sequential planting method was developed to screen rice plants with durable resistance against rice blast in a short time, and applied for several years in Korean rice breeding program. In this study, we showed the advantages of a sequential planting method compared to other pathogenicity tests. The correlation analysis among three pathogenicity tests and other factors demonstrated that durable resistance depended on the average of diseased leaf area and the number of compatible pathogens. Significant correlations were found in the nursery test but not in the field test result. In addition, we traced changes in the pathogen population during sequential planting stages through re-isolation of the pathogen. The portion of compatible pathogens was increased during sequential planting. Through this study, we provide an effective sequential planting method and direction of durable resistance in a breeding program.

• Korean Journal Plant Pathology
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• v.2 no.2
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• pp.69-81
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• 1986

Thirty two rice cultivars which have been cultivated or used as breeding materials in Korea were tested for screening rice cultivars resistant to leaf blast at adult-plant stages in the blast nursery hill plots. When compared on the basis of disease severities in individual leaves at different growth stages of rice plants under natural field infection, the 16 indica-japonica hybrids tested were highly resistant but the 16 japonica cultivars tested showed various degrees of resistance to leaf blast. With aging of rice plants, the quantitative levels of resistance to leaf blast increased in all the cultivars, although the levels of resistance to leaf blast varied according to rice genotypes. The leaf position of rice plants in which changed from susceptible to resistant reactions varied also with rice genotypes. The susceptible reactions of the rice cultivars to Pyricularia oryzae were distinctly changed to a resistant reaction on upper leaves of rice plants. The rice cultivars, in which the quantitative level of resistance to leaf blast was higher, were resistant on the lower leaves of rice plants. The cultivars Akibare, Palkeum, Jinheung, Olchal, Dobong and Ginga which drastically decreased blast infection at late growth stage were evaluated as adult-plant-resistant to leaf blast in the field. The adult-plant-resistant cultivars became resistant to leaf blast, both qualitatively and quantitatively, as rice plants matured.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.11a
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• pp.95-97
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• 2000

• Korean Journal of Breeding Science
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• v.42 no.4
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• pp.390-396
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• 2010

A weedy rice, Ganghwaaengmi 11, shows high level of leaf blast resistance. The chromosomal number and locations of genes conferring the leaf blast resistance were detected by QTL (quantitative trait loci) analysis using SSR markers in the 120 RILs (recombinant inbred lines) derived from the cross between Nagdongbyeo and Ganghwaaengmi 11. Ganghwaaengmi 11 expressed compatibility with 20 of the 45 inoculated blast isolates, in contrast to Nagdongbyeo with 44 compatible isolates. To identify QTLs affecting partial resistance, RILs were assessed in upland blast nursery in three regions and inoculated with selected nine blast isolates. QTLs for resistance to blast isolates were identified on chromosomes 7, 11 and 12. Three QTLs associated with blast resistance in nursery test at three regions were also detected on chromosomes 7, 11 and 12. The QTL commonly detected on chromosome 12 was only increased blast resistance by Ganghwaaengmi 11 allele. This QTL accounted for 60.3~78.6% of the phenotypic variation in the blast nursery test. OSR32 and RM101 markers tightly linked to QTL for blast resistance on chromosome 12 might be useful for marker-assisted selection (MAS) and gene pyramiding to improve the blast resistance of japonica rice.

• Korean Journal of Agricultural Science
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• v.16 no.2
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• pp.129-137
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• 1989

This experiment was undertaken to clarify derivation of resistance of Tongil type of rice varieties to rice blast in Korea and to classify Tongil type of rice varieties on the basis of their rice blast reactions in th blast nursery test. 1. The resistance of Tongil, Josaengtongil, Yeongnamjosaeng, Hwanggeumbyeo, Honamjosaeng, Noupung, Milyang 21, Milyang 22, Milyang 23, Raekyung, Manseogbyeo, Yongmunbyeo and Yongjubyeo to rice blast was derived from IR 8 or IR 24. 2. The resistance of Milyang 20, Nampungbyeo and Milyang 42, and Samseongbyeo, Seogwangbyeo, Pungsanbyeo and Shingwangbyeo to the rice blast was derived from IR 946 and IR 1539, and IR 1545, respectively. 3. The resistance of Palgwangbyeo, Sujeongbyeo, Hangangchalbyeo, Baegunchalbyeo, Samgangbyeo and Weonpungbyeo, and Taebaegbyeo and Chupungbyeo, and Kayabyeo to the rice blast was derived from IR 2061(IR 29), IR 747 and IR 32, respectively. 4. Cheongcheongbyeo, and Jungweonbyeo and Namyeongbyeo, and Changseongbyeo to the rice blast was derived from IR 2035, IR 5533, and HR 2797 and HR 1671, respectively. 5. Tongil type of rice varieties was classified into Tongil group, Milyang 30 group, Baegyangbyeo group and Taebaegbyeo group.

• Korean Journal of Breeding Science
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• v.40 no.4
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• pp.394-400
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• 2008

Blast resistance of one hundred and thirty-one rice cultivars bred in Korea was tested with thirty Korean isolates and twenty-two Philippines isolates using three screening methods. In the blast nursery conducted in Korea and in the Philippines, average disease index of rice cultivars were 4.6 and 2.2, respectively. Seventy-nine cultivars showed different resistance reaction in Korea and in the Philippines, and 19 cultivars showed the same resistant reaction in two locations. In the seedling test, Korean blast isolates displayed different levels of virulence. 93-093, a Korean isolate, was compatible with 90 cultivars whereas 97-057 showed a compatible reaction with 13 cultivars. Twenty-three cultivars showed high level of resistance against Korean and Philippines isolates but Chucheongbyeo, Heugnambyeo, and Manmibyeo showed susceptible reaction to all blast isolates. Through the sequential planting test in Korea and in the Philippines, Palgongbyeo and Seomjinbyeo displayed durable resistance, and Nagdongbyeo and Gihobyeo showed high level of disease infection over the planting time. These results indicate that blast isolates collected in two countries have different genetic background and number of compatible isolates should be considered in definition the durability of rice cultivar to rice blast.

• Korean Journal of Breeding Science
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• v.40 no.4
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• pp.408-413
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• 2008

Rice blast resistance is considered one of the most important traits in rice breeding and the disease, caused by Magnaporthe grisea Barr, has brought significant crop losses annually. Moreover, breakdown of resistance normally occurs in two to five years after cultivar release, thus a more durable resistance is needed for better control of this disease. We developed a new variety, Keumo3, which showed strong resistance to leaf blast. It was tested in 2003 to 2007 at fourteen blast nursery sites covering entire rice-growing regions of South Korea. It showed resistance reactions in 12 regions and moderate in 2 regions without showing susceptible reactions. Durability test by sequential planting method indicated that this variety had better resistance. Results showed that Keumo3 was incompatible against 19 blast isolates with the exception of KI101 by artificial inoculation. To understand the genetic control of blast resistance in rice cultivar Keumo3 and facilitate its utilization, recombinant inbred lines (RIL) consisting of 290 F5 lines derived from Akidagomachi/Keumo3 were analyzed and genotyped with Pizt InDel marker zt56591. The recombination value between the marker allele of zt56591 and bioassay data of blast nursery test was 1.1%. These results indicated that MAS can be applied in selecting breeding populations for blast resistance using zt56591 as DNA marker.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.361-370
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• 1982

The effects of climatic factors on organisms lire variable and complex, and it, however, can be interpreted in terms of those on the distribution and those on the population densities. The distribution of an organism may largely be determined by the temperatures, except some temporal organisms which are depended on the air mass movements. Population density of an organism is determined by various climatic factors, such as previous winter temperature, temperature of growing season and rainfall. The start of growing season of the rice plants has been shifted to earlier since last decade in Korea. This may mean that the overall climatic condition during the growing season might be considerably different from those in past years, and such a difference in climatic conditions might have close relation with the recent status of the diseases and insect pests through direct effects on the physiology and population dynamics of the organisms, as well as through on the biotic associations of the pest organisms. The white back planthopper and brown planthopper have become the key insect pests in Korea in recent years. They are migratory and have high reproductive pontentials and more generations than average residential insects. The synchronization of the migrants and physiological condition of the rice plants seems to be the important factors in relation to the recent outbreaks of these insects; the high reproductive rate can be obtained with the growth stage of rice being 30-50 days after transplanting. The modication of the microclimate associated with high plant density and some other introduced new cultural techniques also have some relation with the outbreak. The key diseases of the rice are the blast disease, sheath blight and the bacterial leaf blight. For the rice blast, the seedling blast and leaf blast during the early growing season and the neck blast, have become more serious, the former may be related to hotbed nursery and the later may be related to the high humidity in early August, and synchronization of the heading time which has been shifted to early part from middle or late part of August. In general, for the rice diseases, the development of the new races have been the most serious which are largely resulted from the introduction of the new varieties, but it also seems to be related with the prolonged periods of the favorable condition associated with the shifted growing seasons. In general, the diseases and insect pest problems have become much more variable and complex, and control measures should be based on the thorough knowledge of the ecology of the pest organisms, that is, effects of various environmental factors on the disease cycle; spore release, spore deposition, infection, colonization and sporulation of the disease organisms, and those on the development, reproductive potentials, dispersal, age specific responses of the insects. The well organized real-time pest management systems, such as alfalfa weevil management system developed at the Purdue University in U.S., is the prime importance for the implementation of the pest management principles.

• Korean Journal of Breeding Science
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• v.43 no.6
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• pp.620-624
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• 2011

'Hwaweon 4' was developed from a cross between the African upland cultivar, 'Moroberekan' and 'Ilpumbyeo' based on marker-aided backcross selection. The recurrent parent 'Ilpumbyeo' is a high grain quality cultivar with medium to late maturity. 'Hwaweon 4' is nearly isogenic to 'Ilpumbyeo' except a small Moroberekan introgressed segment on chromosome 4 harboring the resistance gene for blast. The preliminary and replicated yield trial was conducted at Chungnam National University in 2006 and 2007. The local adaptability test was carried out by the National Seed Management Office (NSMO) from 2008 to 2009. This cultivar was registered to NSMO with a cultivar designated as 'Hwaweon 4'. This cultivar averaged 76 cm in culm length and has medium growth duration. Milled rice of 'Hwaweon 4' is translucent and the grain quality traits are comparable to those of the recurrent parent. It has low protein content. The yield potential of 'Hwaweon 4' in grain was about 6.31 MT/ha at the ordinary fertilizer level for two years. This variety showed highly resistance reaction at the blast nursery test at four locations and also at the sequential planting method. This resistance is due to the resistance gene designated as Pi45(t) on chromosome 4 introgressed from the donor parent, 'Moroberekan'. The Pi45(t) gene would be useful inenhancing resistance to blast in rice breeding program.