• Research in Plant Disease
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• v.18 no.4
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• pp.324-330
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• 2012

This study was conducted to investigate the association of race distribution of Pyricularia oryzae with rice cultivar and location. Races present in a given location were different in cultivars, and the races from a given cultivars were different by location. For precise study of race distribution, it needs to identify isolates by considering cultivation ratio and collection area. There are great differences between the resistant degree in the upland blast nursery and on the resistant degree of the leaf blast and panical blast in the paddy field. The number of virulent races in a rice cultivar was not related with the resistant degree in blast nursery or in paddy field.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.4
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• pp.297-301
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• 1990

The study was conducted to investigate the effects of diatomearth(pH 3 and CEC 20me/100g) on the adjustment of nursery soil pH and on the growth of rice seedling in the tray. The results are as follows ; 1. The soil pH and damping-off of rice seedling were decreased with increase in diatomearth application. 2. Ten to fifteen percent of diatomearth was required to adjuse the optimum soil pH range of 4.5-5.5. 3. Changes in nursery soil pH adjusted by diatomearth were less than those by sulfuric acid during the incubation period. 4. Diatomearth application increased dry weight and height of rice seedling.

• Korean Journal of Plant Resources
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• v.27 no.6
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• pp.687-700
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• 2014

Rice blast (Magnaporthe oryza B.) is one of the most important diseases in rice that causing great yield losses every year around the world. It is important to screen valuable genetic resources for improving blast resistance. This study was conducted to identify the blast resistance in 279 Korean rice landraces using blast nursery tests and isolate inoculum screening. The results showed that 11 landrace accessions found to be resistant to rice blast in blast nursery and inoculation screening tests and the degree of lesions in most accessions showed that they were susceptible to reactions. In order to find the distribution of blast resistant genes, a molecular survey was conducted to identify the presence of major blast resistance (R) gene in 279 Korean landraces. The results revealed that their frequency distribution was Pik-m (36.2%), Piz (25.4%), Pit (13.6%), and Pik (10%). Besides, the frequency distribution of Piz-t, Pii, Pik-m/Pik-p, Pi-39(t), Pib, Pi-d(t)2, Pita/Pita-2 and Pi-ta genes were identified as less than 10%. The results did not consist with the reactions against blast diseases between genotypes and phenotypic part of the nursery tests and isolate inoculation. For concluding these results, we used genome-wide SSR markers that have closely been located with resistance genes. The PCoA analysis showed that the landrace accessions formed largely two distinct groups according to their degree of blast resistance. By comparing genetic diversities using polymorphic information contents (PIC) value among the resistant, total and susceptible landraces, we found that PIC values decreased in four SSR markers and increased in six markers in the resistant accessions, which showed contrary to total and susceptible groups. These regions might be linked to resistance alleles. In this study, we evaluated the degree of blast resistance and the information about the distribution of rice blast resistant genes in Korean rice landraces. This study might be the basis for association analysis of blast resistance in rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.184-188
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• 2001

This study was conducted to find out the basic informations related to the rice cultivation using the infant seedlings. Infant seedlings with different nursery Periods were compared for the growth and grain yield of rice at the National Crop Experiment Station in 1997. The highest sound seedling ratio of 93.9% was observed in 8-day old seedling, followed by 88.9% of 12-day, 82.0% of 16-day, and 80.8% of 20-day, The endosperm remained 52.5% in the 8-day old seedling at transplanting and decreasingly with increasing nursery period. Missing hills at transplanting were more in 16-day and 20-day old seedling than in 8-day and 12-day old seedlings, 5.1-5.2% in 8-day and 12-day growing seedling, 6.7% in 16-day and 7.8% in 20-day old seedling. Rooting ability was observed highest in 8-day, followed by 12-day, 16-day and 20-day old seedling. The milled rice was lower by 5-16% in 12-day, 16-day and 20-day old seedling than in 8-day old seedling of 6.18 t/ha. It was found that the 8-day and 12-day old seedling provided more advantage for sound seedling ratio, endosperm remaining, missing hill during transplanting, rooting ability and grain yields than 16-day and 20-day old seedlings.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.144-150
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• 2000

A field case study was performed to investigate optimum cropping technique of direct seeded rice. In addition, an economic analysis was made to see the effect of this method. Field study was performed at a 2.1㏊ paddy field in Kimjae city, Chonbuk province from 1991 to 1999. Various direct seeding method such as dryland seeding, wetland seeding, and no-till wetland seeding were introduced. Optimum cropping techniques such as when and how to manage the rotary till, water supply, herbicide application, and ponding depth were developed for different cropping methods. Based on this study ￦640,000 per ㏊ can be saved by direct seeding due to no nursery cost, and ￦l,220,000 per ㏊ can be saved by no-till and no nursery cost. With further study these cropping techniques including the no-till direct deeding proves to be advantageous these can be adopted for the most of the paddy fields in Korea.

• Korean Journal Plant Pathology
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• v.1 no.2
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• pp.109-114
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• 1985

The experiments were conducted to clarify the influence of transplanting date on the occurrence of rice virus in field condition of 1984. The rate of RBSDV (rice black-slreaked dwarf virus) viruliferous vector, smaller brown planthopper (Laodelphax striatellus Fallen), was shown to be $13.6\%$ at the 2nd adult and that of rice stripe virus (RSV) viruliferous was $6.7\%$ at the 2nd adult. The vector in the field was begun to come from May 29, the maximum densities were 19.6 insects per hill on June 13 in cultivar Chucheongbyeo, 19.3 in Nagdongbyeo, 7.4 in Cheongcheongbyeo and 4.9 in Samgangoyes. The number of vectors per hill was inclined to increase by early transplanting. Although the infection of rice virus in nursery bed was not recognized until May 30 transplanting, the nursery infection could be seen from June 10 transplanting. The highest rate of nursery infection with RSV was $4.1\%$ at June 10 transplanting plot, and that of RBSDV was $14.2\%$at June 20 trans planting plot. The infection of rice virus in paddy field was the highest at May 20 transplanting plot, the lowest at July 10 plot. The earlier transplanting, the more severe occurrence of rice viruses. Occurrence of infected plants with RBSDV was shown to increase more rapidly at May 20 and May 30 planting plot than May 10 plots. However, the occurrence of infected plant with RSV was more rapid at May 10 transplanting plot than May 20 and 30.

• Korean Journal of Medicinal Crop Science
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• v.22 no.5
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• pp.363-368
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• 2014

This study was conducted to find out the optimum composition of nursery soil for raising seedling of ginseng (Panax ginseng C. A. Meyer). Total 9 kinds of raw materials were used such as peat-moss, perlite, leaf mould, rice bran, gull's guano, castor-oil plant bark, palm bark, cow manure and chicken manure for optimum composition of nursery soil in ginseng. Occurrence of damping-off in ginseng was lowered about 50% in nursery soil type 1, 2 and 4 than in other types nursery soil in June, and occurrence rate of rusty root also lowest in nursery soil type 1. As the salinity of nursery soil increased, so did the occurrence of physiological disorder in ginseng seedling. The cause of salinity increasing in nursery soil has closely relation to $NO_3-N$, $P_2O_5$ and $Na^+$ content. Plant height, root length, diameter and weight were longer and heavier in nursery soil type 1 (mixing ratio of peat-moss, perlite and leaf mould was 50 : 20 : 30 based in volume) than in other types of nursery soil. So nursery soil type 1 was selected for raising seedling of ginseng. pH and electric conductivity (EC) of selected nursery soil type 1 was 5.55 and 0.13 dS/m. Contents of $NO_3-N$ and $P_2O_5$ were 21.0 and 40.0 mg/L, and $K^+$ 0.36, $Ca^{2+}$ 3.38, $Mg^{2+}$ 2.01 and $Na^+$ $0.09cmol^+/L$, respectively.

• Current Research on Agriculture and Life Sciences
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• v.24
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• pp.23-27
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• 2006

Seedling characteristics of rice on nursery covered with different weight of polypropylene spunbonded fabric(PSF) were investigated to determine the optimum thickness of PSF for raising of healthy rice seedlings. Four different thickness of PSF 40, 60, 80 and $100g/m^2$ were used in the seedling nursery with a conventional polyethylene(PE) film. PSF and PE were taken off in 20 days after sowing(DAS) on April and in 10 DAS on June. Plant height of 20- and 30- day old seedlings in PSF covering nursery was slightly taller as the increase of PSF thickness from $40g/m^2$ to $100g/m^2$, but number of leaves and shoot dry-weight of the seedlings was reduced. Root solidity of seedlings grown in lighter PSF ($40{\sim}60g/m^2$) covering nursery was more favorable than that in relatively heavier PSF($80{\sim}100g/m^2$). The optimum thickness of PSF for the raising of healthy seedlings was $40{\sim}60g/m^2$ PSF at sowing on April 20 and April 30 for single cropping, and $40g/m^2$ PSF on June for double cropping based on the growth characteristics of seedlings investigated at seedling nursery covered with different thickness of PSF.

• Journal of Practical Agriculture & Fisheries Research
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• v.13 no.1
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• pp.19-26
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• 2011

The machine transplanted rice has highly extended in the Republic of Korea due to a wage rise since 1976 and thus rice seedling raising nursery method has shifted from field into polyethylene film house. The rice seedling grown under a polyethylene film house was weak and tall because of limited sunlight and wind and so there was so complained among rice growing farmers in terms of missing hill and broken seedling after machine transplanting. In recent iron-coated seedling has reported on healthier and stronger than that of polyethylene film house. These seedlings were more stiff and thus more easy to handle during transplanting and less missing hills. The Iron-coated seed was proven to more stiff like seedling height, root growth and weight of shoot and root growth. This was more convenient during transfer of seedling raising box im machine transplanting. Thus, this study was carried out to grow a stiff and healthy seedling growth and development for machine transplanting. There were a normal seed germination and sprouting after iron-coated seeds treatment and this seedling was smaller and stiffer than that of untreated control. The leaf number and root growth of seedling which was iron-coated seeds would be better and total seedling fresh weight was greater than that of untreated control.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.2
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• pp.196-202
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• 2008

To establish a cultivation system of Sedum sarmentosum using a rice nursery tray ($30{\times}60{\times}3\;cm$) in non-heating plastic film house, cuttings of two local strains (Wanju and Keumsan) were prepared and planted at different planting densities (40, 60 and 80 cuttings per tray) on September 7th, and subsequent growth and yield at pre- and post-winter season were investigated. When pre-wintering growth were measured at 60 days after planting, high planting density (80 cuttings/tray) decreased leaf length and lateral shoot number per plant compared to 40 cuttings/tray. When post-wintering growth were measured on April 20th, no significant growth differences as affected by planting density were observed in Keumsan strain, while decreased stem diameter, node number and leaf number were observed in Wanju strain planted at 80 cuttings/tray compared to 40 cuttings/tray. Fresh and dry weights were not significantly different as affected by planting density, but those were significantly increased in Wanju strain compared to Keumsan strain. When regrowth characteristics followed by the first harvest were measured on June 5th, significantly increased stem number was observed at 80 cuttings/tray compared to 40 cuttings/ tray. Fresh and dry weight were significantly increased in Keumsan strain planted at 80 cuttings/tray compared to 40 cuttings/tray, and dry weight were increased in Wanju strain compared to Keumsan strain. Wanju strain showed higher shoot yield, thicker stem, shorter node and larger leaf, and non-succulent stem under high planting density compared to Keumsan strain. Accordingly, the optimum density was 40 cuttings per tray, and Wanju strain was adequate for the cultivation system using a rice nursery tray.