• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.169-176
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• 2016

Although chemical fertilizers have a quick effect and broad applicability to agricultural fields, they have caused many problems like increasing soil acidity or decreasing soil organic matters. Environmental-friendly agriculture has been attempted in various ways such as organic agriculture, natural farming, low input and sustainable agriculture. The common interest of all environmental-friendly systems is to decrease burden to agricultural environment by low input of agricultural labor and materials. This study was conducted to estimate overwintering capacity and genetic distance among Chinese Milk Vetch (Astragalus sinicus, CMV) collections based on morphological characteristics and AFLP (Amplified fragment length polymorphism) analysis. Furthermore, the effect of CMV as green manure was observed in mix-cultured paddy fields with rice, sesame and sweet-potato. An another objective of this study was also to compare the pattern of weed occurrence in paddy fields with or without CMV and different rice transplanting times. The CMV collected from Paju district in central region of Korea was successively occurring through self-reseeding without artificial management. However, there was no noticeable difference in growth habit between Paju native CMV and introduced CMV from China which is currently used in farm fields. On the basis of multi-dimensional scaling and tree analyses, there are no significant difference of agricultural growth characteristics among Paju and chinese collections only excepting leaf angle and root length. The flowering time of Gurye collection was fast for 1 week as compared to other collections. AFLP that was commonly used for plant classfication, was applied to exam the genetic variation of CMV collections. Total 579 PCR products and 336 polymorphic fragments were generated using 8 primer pairs.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.2
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• pp.117-121
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• 2001

This study was carried out to investigate the effects of rice cultivation of no-tillage seeding on the physicochemical properties and rice yield in the paddy soil of Milk vetch (Astragalus sinicus L.) established. The number of Milk vetch establishment was 256 per $m^2$ in the before experiment but 440 per $m^2$ in the after experiment. The seed numbers of Milk vetch were sufficient that Milk vetch seed were not sown again in the next year. Soil physicochemical properties of the plot of Milk vetch cultivation were similar to the conventional plot. The amount of weed occurrence was 87g dry weight per $m^2$ in the conventional but not occurrence in the sowing of Milk vetch establishment. Rice yield was 4.9ton per ha in the conventional and 4.5 ton per ha in the soybean seeder sowing of Milk vetch establishment.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.111-111
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• 2003

Several fungal isolates were isolated from diseased monochoria(Monochoria vaginalis, weed of paddy field), which has an resistance to sulfonyl urea(S.U.) herbicide, and were evaluated in the laboratory and greenhouse as potential mycoherbicide. Eight fungi, Alternaria sp., Colletotrichum sp., Curvularia sp., Paenicillium sp and etc. were observed in the isolates. Pathogenicity testing were done on the monochorias in the greenhouse. Monochorias were inoculated with suspensions containing conidia of each isolate at the rates of 1.0 ${\times}$ 10$\^$5/ conidia/ml and 0.1％ Tween 80 with hand-gun sprayer. Curvularia sp. and an unidentified fungal isolate caused 90-95％ mortality on the monochorias 15∼20 days after inoculation. However the other isolates induced slight symptom of disease on the monochorias. In the early stage of disease development sun-burn appearance was shown at the infected site and the last infected leaves and stems were withered to death. Subsequently the pathogenicity on the rice was evaluated with above two effective isolates. From the test an unidentified isolate showed pathogenicity on the rice but Curvularia sp., named as DBB2003, didn't. Now the mass production and formulation using Curvularia sp. DBB2003 are in progress and the field test will be followed. Combination product with Curvularia sp. DBB2003 and chemical herbicide will be more effect to control the monochoria resisted on S.U. herbicide and need to be further tested.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.191-196
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• 1999

In rice-barley cropping systems, efficient utilization of barley straw is essential, both to improve the soil fertility and to conserve the environment. In order to identify the effects of barley straw mulch rates in rice cultivation, a rice cultivar, 'Gancheogbyeo', was directly seeded on a no-tillage field synchronized with barley harvesting with five barley straw mulch rates, i.e., 0, 2.5, 5.0, 7.5 and 10.0 ton h $a^{-1}$ and agronomic characters of rice and soil nitrogen were determined. The increasing of barley straw mulch rates. Dominant weed species, chestnut, occurred in large amounts in no mulching or lower mulch rates than in higher mulch rates. The content of N $H_4$$_{＋}$-N in soil applied with high barley straw mulch rates was lower during the month after seeding, and then it was higher at heading date, compared with lower mulch rates or no mulch plot. As the barley straw rate increased, maximum tillering stage was delayed, and plant height was reduced. Although the lodging of rice plants was seldom observed in all plots, the breaking strength of the culm was significantly higher in the mulch rate of 10.0 ton h $a^{-1}$ . With an increase of barley straw mulch rate, the effective tillering rate and spikelet number $m^{-2}$ decreased while ripened grain ratio increased. The rice grain yield was slightly decreased with an increase of barley straw mulch rate, although significant differences were not found all barley straw mulch rates. These results suggest that there is no significant yield loss although the total barley straw production, approximately 5.0 ton h $a^{-l}$ in the present study, apply in the paddy for the following rice cultivation by no-tillage direct seeding.ect seeding.

• The Korean Journal of Pesticide Science
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• v.11 no.1
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• pp.52-58
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• 2007

ALA (5-aminolevulinic acid) has been proposed as a tetrapyrrole-dependent photodynamic herbicide and insecticide by the action of the protoporphyrinogen IX oxidase (Protox IX). The present study was conducted to determine growth responses of plant and insects to ALA, biodegradable biopesticidal substance. In the paddy condition experiment, plant height and shoot fresh weight of barnyardgrass (Echinochloa crus-galli) was more reduced by ALA than rice plants, even though both plant species show great phytotoxicity. Hairy crabgrass (Digitaria sanguinalis), a monocot weed, was more sensitive to ALA at 5mM under upland condition when ALA applied on the foliage, compared with soybean (Glycine max) as a dicot crop. ALA solutions were tested for their insecticidal and larvicidal activities against Spodaptera exigua (Hubner) and Tetranychus urticae Koch. by foliar application and leaf-dipping method. The result showed higher insecticidal activity of ALA at 10mM and its mixture with insecticide luferon against S. exigua. Strongest insecticidal activity against T. urticae was observed from the ALA solution at 10mM 72 days after application. This results show that ALA solution had potent herbicidal and insecticidal activities against agricultural pests even though their activities were lower than those of synthetic pesticides.

• Research in Plant Disease
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• v.17 no.1
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• pp.82-85
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• 2011

Bakanae disease symptom were observed in barnyard grass in paddy field in Heanam, Jeonnam. The infected plants were blighted and white mass of spore were formed on the stem. Fusarium species were isolated from infected stem and the isolates were identified as Fusarium fujikuroi based on their morphological and molecular characteristics. The isolates of F. fujikuroi were assigned to reference of F. fujikuroi among related Fusarium species based on the translation elongation factor 1-alpha gene sequence. Pathogenicity of the fungal isolates was confirmed on seedlings of rice and barnyard grass by artificial inoculation. The results indicated that barnyard grass can be inoculum source of Bakanae disease on rice. Thus, effective weed management is necessary to Bakanae disease control and healthy seed production.

• Plant Resources
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• v.1 no.1
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• pp.43-48
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• 1998

The objective of this study was to determine how elevated $CO_2$ and temperature affected early growth and competition between direct seeded rice (Oryza sativa) and a common paddy weed (Echinochloa glabrascens). By using temperature gradient chambers. Rice and E. glabrescens were grown for 5 weeks at ratios of 1:0. 3:1 and 0:1 at three temperatures ($16.4^{\circ}C,\;19.8^{\circ}C,\;and\;22.2^{\circ}C$) and either in ambient (361ppm) or elevated (566ppm) $CO_2$. For both species. elevated $CO_2$ had no effect on mainstem leaf number while air temperature had a slight positive effect which was greater in E. glabrescens than rice. With elevated $CO_2$ rice leaf area index and plant height increased alightly in all species combinations but no increases were observed for E. Glabuescens. For rice in all combinations. elevated $CO_2$ tended to increase the rot and total biomass much more than any other growth parameters: the increases in root and total biomass resulting from elevated $CO_2$ ranged from 16% to 40%. depending on air temperature. At the lowest temperature, the decrease in rice biomass in combination with E. glabrescens was significantly greater at elevated $CO_2$ (18%) than ambient $CO_2$ (3%). At the highest temperature, however, the decrease in rice biomass at elevated $CO_2$ (22%) was less than that at ambient $CO_2$ (36%). The competitive ability of rice as measured by the decrease in biomass when grown in combination with E. glabrescens depended strongly on root growth and/or allocation. These results suggest that at higher temperatures elevated $CO_2$ could enhance the competitive ability of direct seeded rice during early growth. However, at lower temperatures. the competitive ability of E. glabrescens seems to be greater.

• Journal of Microbiology and Biotechnology
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• v.20 no.12
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• pp.1744-1749
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• 2010

The role of endophytic fungi in plant growth and development is well documented. However, endophytic fungi with growth promotion capacity have never been isolated from weeds previously. In the current study, we isolated 8 fungal endophytes from the roots of Monochoria vaginalis, a serious weed of rice paddy in Korea. These isolates were screened on Waito-C, in order to identify plant growth promoting metabolites. Two fungal isolates (M5.A & M1.5) significantly promoted the plant height and shoot length of Waito-C during preliminary screening experiments. The culture filtrates (CFs) of M5.A and M1.5 also promoted the shoot length of Echinocloa crusgalli. Gibberellins (GAs) analysis of the CFs of M5.A and M1.5 showed that these endophytic fungi secrete higher quantities of GAs as compared with wild-type G. fujikuroi KCCM12329. The CF of M5.A contained bioactive GAs ($GA_3$, 2.8 ng/ml; $GA_4$, 2.6 ng/ml, and $GA_7$, 6.68 ng/ml) in conjunction with physiologically inactive $GA_9$ (1.61 ng/ml) and $GA_{24}$ (0.18 ng/ml). The CF of M1.5 contained physiologically active GAs ($GA_3$, 1.64 ng/ml; $GA_4$, 1.37 ng/ml and $GA_7$, 6.29 ng/ml) in conjunction with physiologically inactive $GA_9$ (3.44 ng/ml), $GA_{12}$ (0.3 ng/ml), and $GA_{24}$ (0.59 ng/ml). M5.A and M1.5 were identified as new strains of Penicillium sp. and Aspergillus sp., respectively, based on their 18S rDNA sequence homology and phylogenetic analysis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.1
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• pp.61-69
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• 1977

The affect of perennial weeds to rice yield and rice growing was evaluated. Rice heading date was shortened 1-4days and rice culm length was shortened 5-10cm in heavy weed growing condition. The ratio of yield reduction were about 50% in Cyperus serotinus, about 57 in Potamogeton distinctus in both rice varieties and about 60% of Eleocharis kuroguwal in heavy perennial growing condition.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.21 no.2
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• pp.258-268
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• 1976

This study was conducted in order to know the ecology and to establish the control method of Potamogeton distinctus A. BENN. The tubers of Bog pond weed was almostly located at soil depth of 10 cm to 20cm, germination rates and number of formed tubers were different according to transplanting depth of soil. Effects of herbicides application on weeds were different according to leaf-stage of pondweed, and the pondweed were withered to death by absorption of Avirosan into the leaves. It was suitable to keep water depth at 3cm level until about a week after Avirosan application.