• Korean Journal of Weed Science
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• v.32 no.3
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• pp.256-262
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• 2012

This experiment was conducted to determine the agronomic characteristics for selection of the excellent barnyard millet and the herbicidal response for their weediness prevention in paddy rice. IT170609, IT195422 and EV2012 have produced more dry matter compared to other barnyard millets tested. In varietal characteristics by heading date, IT170609 showed medium maturing type and IT195422 and EV201 had late maturing type. The germination rate of IT170609, IT195422 and EV2012 on temperature was higher than Echnochloa oryzicola of native species, and it was definitely distinctive at 20 and $25^{\circ}C$. In the herbicidal response for their weediness prevention in paddy rice, imazosulfuron+benzobicyclone+penoxsulam SC showed control effect the extend of over 90% to IT170609, IT195422 and EV2012. Cyhalofop-butyl EC, penoxsulam SC and metamifop EC were very effective by 6~7 leaf stage of barnyard millets tested.

• 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.30 no.4
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• pp.380-389
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• 2010

Transgenic herbicide-resistant sweet potato plants [Ipomoea batatas (L.) Lam.] produced through a biolistic transformation were used in this study. The objective of this research was to find out a rapid and reliable assay method for confirming glufosinate-ammonium resistance. The techniques tested include whole-plant bioassay, one leaf bioassay, and leaf disk bioassay. Parameters investigated in this study were leaf injury and ammonium accumulation at 1 and 5 days after treatment of glufosinate-ammonium. In the leaf disk bioassay, leaf injury of the transgenic line 7171 was 1.9-fold less affected by glufosinate-ammonium than the wild type. The leaf injury of 7171 in one leaf and whole-plant bioassays was 59- and 92-fold less affected by glufosinate-ammonium, respectively, compared with that of the wild type. Leaf disk, one leaf, and whole-plant bioassays showed that ammonium accumulation of the 7171 was 2 to 20-, 4 to 43-, and 6 to 115-fold less affected by 0.5-5 mM glufosinate-ammonium than that of the wild type. All three bioassays successfully distinguished the resistance from the transgenic lines, but one leaf bioassay is the simplest and quickest. Leaf injury and ammonium accumulation were the same in leaves 1, 3, 5, 7, and 10 of 3 mM glufosinate-ammonium treated plants or nontreated plants. The one leaf bioassay was chosen as the standard procedure for future confirmation of resistance in transgenic sweet potato because it is a rapid and reliable assay.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.362-367
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• 2013

This study was conducted to develop an efficient control method for water foxtail in the field sowing barley and wheat seeds before rice harvesting. When thifensulfuron-methyl (75%) was applied 0, 5 and 10 days after rice harvesting, little phytotoxicity was observed on both barley and wheat. Percent of water foxtail control with thifensulfuron-methyl (75%) was more than 88% at three different application timing. When butachlor (5%) was applied 5 days before barley and wheat sowing, phytotoxicity on barley and wheat was severe. However, no phytotoxicity was observed on barley and wheat 5 and 10 days after rice harvesting. Percent of water foxtail control with butachlor 0 and 5 days after rice harvesting was 85-89%. However, it dropped to 74-80% when applied 10 days after rice harvesting. In the thifensulfuron-methyl treatment, the dry matter of barley and wheat was 96-108% and 100-108%, respectively when compared with untreated control. While, in the butachlor treatment, the dry matter of barley and wheat was 53-73% and 106%, respectively when compared with untreated control. Therefore, we recommend thifensulfuron-methyl (75%) 0-10 days after rice harvesting or butachlor (5%) 5 days after rice harvesting to provide efficient water foxtail control and safe barley and wheat production.

• Korean Journal of Weed Science
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• v.4 no.2
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• pp.204-210
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• 1984

For weeding on the after-barley cropping soybean, the tank-mix use of postemergence herbicides acifluorfen and haloxyfop-methyl was tested. Acifluorfen has shown the transient leaf-burn on the newly formed soybean leaves, but no growth inhibitions. Under the treatment of acifluorfen only, grassy weeds occurred successively and explosively. However, under the combinated spraying of both herbicides, the grassy weeds could be controlled in a slight antagonistic, the broadleaved weeds in additive, and the total weed species including sedges in synergic tendencies, respectively. Also, to achieve the full-season weeding efficacies for the prominent crop yields, both herbicides are suggested to be mixed with more dosages than 0.245 kg ai/ha of acifluorfen and 0.15 kg ae/ha of haloxyfop-methyl, respectively.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.215-224
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• 2010

A greenhouse experiment was conducted to determine the effects of medium components and shade treatment on the growth, contents of total phenolics and flavonoids, and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity of Youngia sonchifolia. Substrates combined with coco peat and perlite (ratio 70:30 or 50:50, v/v) showed higher plant length, leaf area, and fresh weight than single substrate (P<0.05). Shade treatment also significantly reduced plant height, root length, leaf areas, and fresh weight (P<0.05) with increasing of the degree. Shading treatment, however, increased contents of total phenolics [mg ferulic acid equivalents $kg^{-1}$ dry wt.] and total flavonoids [mg naringin equivalents $kg^{-1}$ dry wt.] in shoot parts of Y. sonchifoli, showing 110.2 to 119.2 and 128.3 to 146.7 mg $kg^{-1}$, respectively. The antioxidant potential of the methanol extracts from the plants dose-dependently increased DPPH free radical scavenging activity, and the activity was higher in shoots (50.2 to 80.8%) than in roots (47.7 to 49.8%), and in shading treatment than in no shade.

• Weed & Turfgrass Science
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• v.4 no.1
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• pp.35-43
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• 2015

To assess the dormancy associated weedy risk of the F1 hybrid generated by hybridization between Brassica juncea (maternal) and Brassica napus (paternal), seed germination, dormancy and longevity were examined sequentially after seed harvest. The F1 hybrids exhibited the intermediate characteristics of their parents in seed germination and dormancy with relatively high dormancy rate of 41.1%. In summer, F1 hybrid seeds buried in the 3 cm soil exhibited greater viability (52.4%) than those in the soil surface with greater seed longevity (74.6%) than its maternal (63.3%) and paternal (33.7%) parents at 100 days of over-summering in soil. In winter, F1 seeds buried in the soil surface were more viable than those in the 3 cm soil with greater seed longevity (83.5%) than its maternal (39.0%) and paternal (71.7%) parents at 100 days of over-wintering in soil. Therefore, it is concluded that F1 hybrid resulted from gene flow from OSR to mustard has high seed dormancy and longevity during summer and winter, suggesting its weedy risk potential. Further studies are required to examine the reproductivity and fitness cost of F1 hybrid to make a clearer conclusion of its weedy risk.

• Weed & Turfgrass Science
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• v.4 no.1
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• pp.18-25
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• 2015

A universal DNA barcoding for agricultural noxious weeds is a powerful technique for species identification without morphological knowledge, by using short sections of DNA from a specific region of the genome. Two standard barcode markers, chloroplast rbcL and matK, and a supplementary nuclear ribosomal Internal Transcribed Spacer (ITS) region were used to examine the effectiveness of the markers for Pooideae barcoding using 163 individuals of 29 taxa across 16 genera of Korean Pooideae. The rbcL and ITS revealed a good level of amplification and sequencing success while matK did not. Barcode gaps were 78.6% for rbcL, 96.2% for matK, and 91.7% for ITS, respectively. Resolving powers were 89.3% for rbcL, 92.3% for matK, and 79.1% for ITS. The matK obtained the best both barcode gap and resolving power. However, it should be considered not to employ matK for Pooideae barcode because of low rate of PCR amplification and sequencing success. As a single DNA marker, rbcL and ITS were reasonable for Pooideae barcode. Barcode gap and resolving power were increased when ITS was incorporated into the rbcL. The barcode sequences were deposited to the National Center for Biotechnology Information (NCBI) database for public use.

• Korean Journal of Weed Science
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• v.17 no.4
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• pp.382-389
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• 1997

Collated data from the 1995-1996 floristic surveys of weeds of arable peat in Selangor district were analysed to assess composition and dominance and spatial distribution pattern based on quantitative and dispersion indices. Forty eight weed species belonging to 19 families of which 31 were broad leaves, 10 grasses and 7 sedges were sampled and these ware translated as 77.8 and 15% of the total cover, respectively, The respective important values were 71.11 and 18%. Ten species in the onder of dominance were Fimbristylis acuminata, Murdannia nudiflora, Hedyotis corymbosa, Ageratum conyzoides, Asystasia gangetica, Cleome rutidosperma, Cyperus sphacelatus, Lindernia crustacea, Ludwigia hyssopifolia of spatial distribution based on variance-to-mean ratios, Llouds mean crowding or Lloyds patchiness indices. Other species were either random or regular in their spatial distribution. Differences in species-dominance and spatial distribution pattern may be attributed to inherent variations in patchiness and fecundity schedules of each weed species, crops, cropping patterns and agronomic practices prevailing in the area.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.279-287
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• 2015

The present research was carried out in order to investigate the occurrence of problematic weed species in Cnidium officinale Makino. Field in South Korea. Total 53 sites of the 3 different regions in S. Korea were investigated from May to October, 2014. In Cnidium officinale fields, the identified weeds were distributed in 35 families and 99 species. Total 5 communities that consist of Commelina communis, Eleocharis kuroguwai, Persicaria vulgaris, Chenopodium album-Acalypha australis, and Galinsoga ciliata dominated the appearance. The weeds occurred in Cnidium officinale fields were divided into three groups in principal component plot analysis (PCA). It was observed that in control weeds plots; 20 plants of Cnidium officinale fresh weight is 739.9 g while the uncontrolled plots have no Cnidium officinale plants. The current investigation could be useful for estimation of future weeds occurrence, weed flora dynamics and establishment of weed control methods in Cnidium officinale fields in Korea.