• FLOWER RESEARCH JOURNAL
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• v.19 no.1
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• pp.15-21
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• 2011

This study investigated the effect of soil mulching materials and methods on weed occurring for the growth and flowering characteristics in Gypsophila plants cultivation. For mulching materials were used black polyethylene (PE) film, black polypropylene (PP), and green polypropylene, and these were mulched in both ridge and furrow (BRF) or only furrow, respectively. The weed was occurred total $146.2g/m^2/yr$ as dry weight in non-mulching, but $4.1{\sim}4.2g/m^2/yr$ in BRF mulching by black or green PP. Also weed control were yearly required 27.9 persons/10a in non-mulching, whereas 2.4 persons/10a in BRF mulching by black or green PP. Flower budding and blooming were roughly delayed in non-mulching and furrow mulching. Flowering characteristics such as flower stalk length, primary branches number, and stem firmness were remarkably improved in BRF mulching of black or green PP. Cut flower yield was increased on black BRF mulching or green PP in summer cultivation, while green PP BRF mulching showed better yield in in autumn cultivation. Mortality rate of Gypsophila plants after summer season was lowest as 12.4% in furrow mulching with black PP, followed by about 19.0% in green PP mulching, but highest as 39.0% in BRF mulching with black PE film. Rosette formation rate was lower in furrow than BRF mulching, and was lowest as 13.1% in BRF mulching with green PP, followed by 15.2~15.8% in BRF mulching with black PE film or black PP. So it was thought that BRF mulching with green PP was highly effective in weed control and improvement of yield and cut flower quality in Gypsophila plants cultivation.

• Weed & Turfgrass Science
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• v.7 no.1
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• pp.15-21
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• 2018

Since sulfonylurea (SU) herbicide-resistant Monochoria korsakowii in Seosan reclaimed land in 1998 was reported first, herbicide-resistant weed species and their area of occurrence have been steadily increasing. In recent years, Sagittaria trifolia resistant to SU herbicides has been reported in Gimhae, Gyeongnam province. While collecting S. trifolia for constructing barcode database of major weeds we were suspicious by the continuous variation in the leave morphology of the species. In order to identify the S. trifolia from S. aginash we barcoded the species collected from domestic using ITS and compared the sequence variation with the ITS sequences of S. aginash downloaded from NCBI. As a result, it was found that the plants collected from the domestic did not have any variation among individuals although they showed wide morphological variation. On the other hand, interspecific variation between S. trifolia and S. aginash was 4.6%. Plants that are difficult to identify using morphological characters can be identified quickly and accurately using the barcode technique. Herbicide-resistant weeds may require different management practices depending on the species even in the same genus. Domestic herbicide-resistant weeds are steadily increasing. Therefore, accurate identification of these species must be preceded for effective weed control.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.390-395
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• 2010

This study was conducted to predict reduction of soybean yield as affected by different densities of Cuscuta pentagona. All data were fitted to Cousens' rectangular hyperbola model to estimate parameters for predicting soybean yield loss. The yield of soybean in the various densities (1 to 48 plants $m^{-2}$) of C. pentagona reduced by 80.3 to 99.7%, respectively. Among yield components, number of pods was the most significantly influenced by weed interferences. The prediction model for soybean yield as affected by weed competition was as follows: Y= 274.6783/(1+4.3522X), $r^2$=0.999 in C. pentagona. Economic threshold levels calculated using cousens' equation was 0.004 plants $m^{-2}$ in C. pentagona.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.289-293
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• 2011

Field experiments were conducted to predict rice yield losses caused by Echinochloa crus-galli (L.)P. Beauv., Bidens frondosa L. and Aeschynomeme indica L. at a range of plant densities under machine transplanted rice cultivation in different regions of Korea in 2006, and to determine their economic threshold levels (ET). All data were fitted to Cousens' rectangular hyperbola to estimate parameters for predicting rice yield loss. The rice yield loss models of Bidens frondosa L. was predicted as y=5.43/(1+0.0113x), $R^2$=0.963, A. indica was y=5.47/(1+0.0332x), $R^2$=0.976 and E. crus-galli y=5.43/(1+0.01552x), $R^2$=0.950. The mean competitivities represented by the parameter, whose reciprocal ($1/{\beta}$) is a weed density reducing crop yield by 50%. Those of E. crus-galli, B. frondosa and A. indica were 0.01552, 0.01113 and 0.0332 in normal-season machine transplanting of Korea, respectively. Single year mean economic thresholds (ET) of A. indica were 0.5, 0.6 and 0.7 plant $m^{-2}$ with the application of flucetosulfuron, flucetosulfuron+imazosulfuron GR and flucetosulfuron+imazosulfuron+carfentrazone GR herbicides, respectively. Meanwhile ET values of 1.6, 1.9 and 1.9 plants $m^{-2}$ for B. frondosa, 1.2, 1.4, and 1.4 plants $m^{-2}$ for E. crus-galli.

• Weed & Turfgrass Science
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• v.4 no.1
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• pp.26-34
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• 2015

Korean Poaceae includes approximately 80 species of the agricultural weeds. Precise species identification is the first step for more effective weed management in the agricultural fields. However, the identification of species in Poaceae is not easy without the assistance of taxonomists or identification experts although they are relatively easy to distinguish from the plants of the other family by the unique characteristics of caryopsis. Thus, DNA barcode was suggested as an alternative powerful technique for species identification by using short sections of DNA from a specific region of the genome. Two standard barcode markers of vascular plants, chloroplast rbcL and matK, and a supplementary nuclear ribosomal Internal Transcribed Spacer (ITS) region were used for barcode of major Korean Poaceae weeds, 403 individuals of 84 taxa. All the barcode markers revealed a good level of sequencing success with the lowest 73.7% for matK and the highest 88.8% for rbcL. The barcode sequences were deposited to the National Center for Biotechnology Information (NCBI) database for public use. Combined matK and ITS showed very high resolving power with 92.9%. Besides the identification of weeds for weed managment, the generated DNA barcode data could be used for many other applications such as rapid biodiversity assessment and conservation prioritization.

• Korean Journal of Medicinal Crop Science
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• v.3 no.2
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• pp.146-150
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• 1995

Weed control in the Korean ginseng(Panax ginseng C.A. Meyer) garden is more difficult than in other crops because the ginseng is a perennial crop and has to be cultivated under the artificial shading. As hand weeding is the only practical means to control weed after crop establishment, a selective herbicide would greatly simplify the control of weed in ginseng garden. In an exploratory experiment, the hervicide Fluazifop-butyl was found to be selectively safe for the Korean ginseng plants. Various rates of Fluazifop-butyl were sprayed on 2-, 3-, and 4-years old ginseng plants as a foliar spray to detect crop injury and to difine their critical concentration. No apparent injury to the ginseng plant was noticable even the doubled application rate of Fluazifop-butyl the based on recommended dosage. Neither abnormal foliar change nor any inhibition in leaf and stem growth was resulted for 2-, 3-, and 4-years old ginseng plants treated with Fluazifop-butyl tripled the recommended usage. The foliar treatments of Fluazifop-butyl did not influence the photosynthesis ability but inhibited the respiration of the ginseng leaf.

• Journal of Plant Biotechnology
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• v.38 no.2
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• pp.105-116
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• 2011

Transgenic zoysiagrass (Zoysia japonica Steud.) expressing the bar gene inserted in the plant genome has been generated previously through Agrobacterium tumefaciens-mediated transformation. The GM zoysiagrass (event: JG21) permits efficient management of weed control of widely cultivated zoysiagrass fields, reducing the frequency and cost of using various herbicides for weed control. Now we have carried out the environmental risk assessment of JG21 prior to applying to the governmental regulatory agency for the commercial release of the GM turf grass outside of test plots. The morphological phenotypes, molecular analysis, weediness and gene flow from each test plot of JG21 and wild-type zoysiagrasses have been evaluated by selectively analyzing environmental effects. There were no marked differences in morphological phenotypes between JG21 and wild-type grasses. The JG21 retained its stable integration in the host plant in T1 generation, exhibiting a 3:1 segregation ratio according to the Mendelian genetics. We confirmed the copy number (1) of JG21 by using Southern blot analysis, as the transgenic plants were tolerant to ammonium glufosinate throughout the culture period. From cross-fertilization and gene flow studies, we found a 9% cross-pollination rate at the center of JG21 field and 0% at distances over 3 m from the field. The JG21 and wild-type zoysiagrass plants are not considered "weed" because zoysiagrasses generally are not dominant and do not spread into weedy areas easily. We assessed the horizontal gene transfer (HGT) of the transgene DNA to soil microorganisms from JG21 and wild-type plants. The bar gene was not detected from the total genomic DNA extracted from each rhizosphere soil of GM and non-GM Zoysia grass fields. Through the monitoring of JG21 transgene's unintentional release into the environment, we found no evidence for either pollen mediated gene flow of zoysiagrass or seed dispersal from the test field within a 3 km radius of the natural habitat.

• Korean Journal of Plant Resources
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• v.26 no.2
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• pp.289-302
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• 2013

Surveys were conducted to study nationwide distribution and identify habitats and host plants of Cuscuta pentagona Engelm. as a parasite. The major habitat types were arable land near agricultural waterways (54.3%), open field near roadside (41.3%) and artificial grassland (4.3%). The investigated host plants of Cuscuta pentagona consist of total 130 taxa: 10 varieties, 1 subspecies, 119 species, 95 genera, and 37 families. Among them, 30 taxa were alien plants. As for the useful plants, there were 59 taxa of edible ones (45.4%), 54 taxa of medicinal ones (41.5%), 13 taxa of ornamental ones (10%), 13 taxa of industrial ones (10%), and 9 taxa of pasture ones (6.9%). On arable land, it caused damage particularly to the growth of agricultural crops such as Oryza sativa L. (Rice) and fruits such as Malus pumila Mill. (Apple) etc. Its growth and distribution may cause economic loss for crops because of the close location of the arable land.

• Weed & Turfgrass Science
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• v.6 no.3
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• pp.196-202
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• 2017

This study was conducted to investigate the change of yield and quality according to seeding time and planting density and to determine effective weed control method in wet-hill-seeding use black colored rice. The most effective weed control system was application of bromobutide thiobencarb five days before seeding followed by bensulfuron mefenacet thiobencarb 12 days after seeding (barnyardgrass at 2.5-3.0 leaf stage). The seedling stand by seeding time and planting density increased with the delay seeding time and high planting density. The heading dates were delayed as the seeding time became late but no difference was found between planting density. The anthocyanin content of black colored rice was higher at late seeding time and lower planting density. The yield of full colored rice was high 80 plants per $3.3m^2$ in seeding on May 30 and June 10. This information could be useful for spreading rice direct seeding by inducing stabilization of wet-hill-seeding use black colored rice.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.159-169
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• 2012

Hormesis is a dose-response phenomenon that is characterized by low-dose stimulation and high-dose inhibition. This biphasic dose-responses have had a long and extensive history in the fields of chemical toxicology, radiation biology and pharmacology. Hormesis has been found from bacteria, fungi, plants and animals, but hormesis in plants has received relatively little attention. Thus principles, occurrence, factors affecting the expression of hormetic responses, and their mechanisms in plants induced by herbicides are reviewed to provide the potentials for crop enhancement. Bromacil, bromoxynil, chloramben, propachlor, terbacil, EPTC, MSMA, and glyphosate at low doses showed stimulatory response in growth. Subtoxic dose of glyphosate increased sucrose content in sugarcane that is used worldwide in sugarcane production. Low dose of protoporphyrinogen-inhibiting herbicides induced increased pathogen defence, and low dose of triazine herbicides improved nitrogen metabolism and increased protein content in some crops. Further researches on potential benefits and risks of hormesis and its mechanism are needed for application of crop enhancement in agriculture.