• Korean Journal of Agricultural Science
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• v.18 no.2
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• pp.93-98
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• 1991

This research was undertaken to clarify derivation of resistance of Japonica type of rice varieties to rice strip virus. 1. The source of resistance to the rice strip virus in rice cultivars of Nagdongbyeo, Hwaseongbyeo, Gwangmyeongbyeo, Yeongdeogbyeo, Dongjinbyeo, Gyehwabyeo, Hwacheongbyeo, Suweon 362, Iri 390, Milyang 64, Milyang 96 and Milyang 101 was derived from rice cultivar of Modan. 2. The resistance of rice cultivars Donghaebyeo, Sinseonchalbyeo, Palgongbyeo, Hwajinbyeo and Somjinbyeo to the rice strip virus was derived from cultivar Milyang 23 and/or Nangdongbyeo. 3. The resistance of cultivars Jinjubyeo, Tamjinbyeo and Yongsanbyeo to the rice strip virus was derived from cultivar HR 769 and/or Milyang 20. 4. The resistance of cultivar Daecheongbyeo to the rice strip virus was deriverl from cultivar Nagdongbyeo and/or HR 769.

• Research in Plant Disease
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• v.18 no.3
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• pp.245-249
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• 2012

The small brown planthopper (Laodelphax striatellus) is one of the most important rice pests in Republic of Korea because it damages rice plants not only by sap-sucking but also by transmitting Rice stripe virus (RSV). Outbreaks of RSV are closely related to outbreaks of the small brown planthopper (SBPH). Therefore, it is very important to control SBPH for the management of RSV. Mass-migrating SBPH collected by aerial net traps in June 2011 at Taeanup, Geunheungmyon and Gonammyon in Taeangun were examined for virus carrier status and effects of the pesticide, 'Myungtaja', on the control of RSV. Among 1,217 SBPH trapped, about 7.7% were detected as RSV positive and 4.4% were positive for Rice black streak dwarf virus (RBSDV) by RT-PCR. After the mass migration, pesticide 'Myungtaja' was sprayed once or twice on rice fields and compared to untreated fields. The incidence of RSV was not affected by the frequency of spraying 'Myungtaja' but was influenced by the time of pesticide treatment. Myungtaja' treatment within 5-7 days after mass migration resulted in the most efficient RSV control, resulting in RSV incidence decreased by 87.6% compared to the control. Therefore, we conclude that pesticide spraying for RSV control was most effective when it was done within 5-7 days after mass migration.

• Korean Journal Plant Pathology
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• v.3 no.2
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• pp.93-99
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• 1987

Six rice cultivars showing various types of resistance or susceptibility to Pyricularia oryzae in the field were used to study the relationship between susceptibility and contents of carbohydrates, amino acids and phenolics at different plant maturities and leaf ages under controlled environmental conditions. No consistent differences between the susceptible cultivars and adult-plant-resistant cultivars were found in terms of the contents of individual carbohydrates, total amino acids and phenolics in rice leaves throughout the plant development. Only the adult-plant-resistant cultivar Dobong had lower contents of inositol throughout the plant development than the other cultivars. The amounts of sucrose, inositol, glucose, and fructose increased in all tested cultivars at eight leaf stage than those at five leaf stage, but slightly decreased at twelve leaf stage. In contrast, total amino acids and phenolics gradually decreased during plant development. With increasing age of rice leaves, the amounts of total soluble amino acids and phenolics gradually increased in healthy fifth leaf tissues, although there were no significant differences between the cultivars. In particular, a high level of phenolics existed in old fifth leaves of the cultivar Dobong. These results suggest that increased resistance to blast of matured rice plants and old leaves may be the two different phenomina derived from the physiological changes occurring during plant development and leaf senescence, probably functioning differently in P. oryzae development.

• Korean Journal of Organic Agriculture
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• v.18 no.1
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• pp.75-82
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• 2010

The purpose of this study is to investigate an occurrence rate of rice stripe virus disease under different rice transplanting time and different rice cultivars. After final harvest, the yield of rice infected by rice stripe virus was obtained on Wangchal cultivar compared to uninfected rice. The results obtained as following: 1) Yield of rice infected by rice stripe virus was decreased by 64% with reduction of culm length, pancile length, number of spike, number of spikelet, and grain filling compared to uninfected rice, 2) An occurrence rate of rice stripe virus disease under different rice planting season was high as order of May 30 > June 15 > July 1. In additional, to reduce a rice stripe virus disease on higher disease occurrence region and susceptible cultivars, rice planting season will be accepted on and after June 15, and 3) Eighteen cultivars were resistance cultivars such as Hwayeongbyeo, Onnuri, Ilmibyeo, Nampyongbyeo, Dongjin2ho, Hopumbyeo, Hwangkeumnuri, Malgeumi, Saenuri, Pungmi1ho, Haechanmulgyeo, Hwangkeumnodeul, Chilbobyeo, Dongjinbyeo, Younganbyeo, Junambyeo, Samkwangbyeo, and Nakdongbyeo. Twenty-one cultivars were susceptible cultivars such as Odaebyeo, Unkwangbyeo, Shinungbong1ho, Manabyeo, Hopyongbyeo, Borami, Damibyeo, Hwangchalbyeo, Sulgengbyeo, Nongrim6ho, Sasanishigi, Yunishigari, Chungmubyeo, Dongjin1ho, Huknambyeo, Guromy, Shanghehanghulna, Heukchalbyeo, Heukhwangbyeo, and Aranghwangchalbyeo.

• Korean Journal of Environmental Agriculture
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• v.15 no.1
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• pp.19-24
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• 1996

To investigate the alterations of ultrastructure of leaves by acid rain, 10mm of SAR(Simulated Acid Rain, pH 2.0, 2.5, 2.7, 3.0, 6.0) were applied to 4 crops(rice, soybean, barley, and radish) at the two day interval. The symptoms of leaf damage by SAR were observed by naked eyes and SEM(Scanning Electron Microscope). The results are summarized as follow: Visible leaf injury were more serious in dicots than monocots such as rice and barley with the order of bean, radish, rice, barley. With the SAR treatment of pH 2.0, histological perturbation of trichome were developed in bean and radish. And with the SAR treatment of pH 2.5, stomata of all tested crops except rice were deshaped.

• Research in Plant Disease
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• v.21 no.2
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• pp.103-106
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• 2015

Isolates of the rice blast fungus show a range of tissue-specificities infecting leaves, nodes, neck and panicles. Although neck and panicle blast cause significantly greater yield losses than the leaf blast, virulence tests of the blast isolates have been performed only rice leaves instead of neck and panicles. In this study, we have developed a virulence test method for neck and panicle blast. We selected three representative isolates from each of leaf, neck, and panicle blast. We observed that severe disease lesions developed on the neck and the panicles when the infected rice plants were incubated in a dew chamber for 48 h instead of 24 h when tested on leaves. Unlike the leaf blast, a typical lesion on the neck and panicles appeared after 14 days post-infection as opposed to 7 days with leaf blast. This method will be applied to examine tissue-specificity of the rice blast fungus isolates.

• Journal of Life Science
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• v.8 no.5
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• pp.492-496
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• 1998

Intact measurement of leaf water content was attempted using the transmission of beta radiation. Prior to the experiments, two tested plants, rice and soybean, were grown in 1/5000a wagner pot. The moisure ratio of plant leaves were measured with the beta radiation transmission method using a G-M detector and $^{99}$ Tc as the beta ray sou-rce. Beta radiation transmission showed a tendancy to increase with the passage of time after leaf cutting. However, it showed a tendancy to decrease with water supply for the lack of water. A positive correlation was found between the leaf water content and beta radiation transmission. The mutiple regression analysis about leaf water content was obtained that the coefficient of partial regression for beta radiation transmission was much higher(rice; -0.863, soybean; -0.904) than that for specific leaf area(rice; 0.007, soybean: 0.004).

• The Bimonthly Magazine for Agrochemicals and Plant Protection
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• v.5 no.1
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• pp.70-72
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• 1984

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.1-5
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• 1980

Comparisons were made between pubescent and smooth leaved cultivars or lines for the brown planthopper feeding preference, adult emergence percent, nymphal period, grain yield and brown rice recovery percent, and found that there were no significant differences of the traits tested between smooth and pubescent.

• Korean Journal Plant Pathology
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• v.1 no.1
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• pp.61-66
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• 1985

Seventy-one strains collected from Korea were classified into three serovars (designated A, B-I and B-II) by using agar gel diffusion test with the antisera produced against Xanthomonas campestris pv. oryzae isolates Q7472 and Q7502. Of 71 isolates tested, 65 isolates belonged to serovar A, 5 isolates were serovar B-I, and one isolate was serovar B-II. The isolates of serovar B-I and B-II could be distinguished clearly from those of serovar A showing marked autoagglutination. Xanthomonas campestris pv. oryzae was serologically diagnosed in rice leaves by agar gel diffusion tests, possibly being distinguished from Xanthomonas campestris pv. olyzicola and E. herbicola. The pathogen could be also serologically detected from the extracts of diseased leaves, squeezed immediately, heated at $100^{\circ}C$ or incubated in PSA. Serological detection of Xanthomonas campestris pv. oryzae is a more reliable and less time-comsuming method.