• Journal of the Korean Geographical Society
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• v.41 no.4 s.115
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• pp.404-417
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• 2006

In order to clarify some characteristics of hydrological cycle in the subalpine zone of Mt. Halla, water balance has been analysed using hydrological data of a first-order drainage basin around Mansedongsan and meterological data of Odeung AWS. The experimental basin extends from 1,595 m to 1,645 m in altitude and has an catchment area of 1.34 ha. It is largely underlain by trachybasalt and covered with sasa bamboo and sedges. Hydrological observations were carried out every 20 minutes from April 15 to September 19, 2004. The basin shows the total precipitation of 3,074 m that is 1.6 to 3 times of those in coastal and intermontane regions. Surface runoff amounts to 850 mm that is equivalent to 27.6% of the precipitation. By contrast, evapotranspiration only accounts for 14.2% of the precipitation, and the remnant of 1,790 m penetrates underground through a basement. The basin is located in the subalpine zone and then it has a high rainfall intensity as well as a large rainfall due to frequent orographic precipitation. But surface runoff usually dose not exceed 30% of the rainfall while Percolation demonstrates about 2 times of the runoff. Compared with granite or gneiss basins in Korea Peninsula, the experimental basin is characterized by a higher portion of percolation in water balance. And it is probably related to the highly permeable basaltic lavas in Jeju Island which are also overlain by porous volcanic soils.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.71-78
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• 2013

An exceptional case of inhabitation of a Sphagnum sp. was firstly confirmed at abandoned paddy terrace (APT) wetland in Ansan. Water sampling for analyzing of physicochemical conditions including nutrients such as NP, $Ca^{2+}$ and $Mg^{2+}$ was performed and the vegetation map for distribution of Sphagnum sp., topographical map, and flora list for companion species were made at field in June 2011. From the results, the Sphagnum sp. in the study site was identified as S. palustre and it covered about 8% of the wetland cover of 3,200 $m^2$. Most distributions of S. palustre were observed at tussock structures as micro-topography by sedges and grasses within a wetland (74%) and the shaded slope area under Pinus densiflora's canopy in wetland boundary (26%). Despite that APT in Ansan is relatively lower wetland in altitude than high moors, the contents of calcium ($0.45{\pm}0.2$) and magnesium ($1.48{\pm}0.6$) ion which are critical limiting factors for Sphagnum spp. were very low levels as well as NP ($PO_4$-P, $0.02{\pm}0.0$; $NO_3$-N, $0.25{\pm}0.3$; $NH_4$-N, $0.06{\pm}0.1$) and it could enable the inhabitation of S. palustre in lower APT.

• Korean Journal of Weed Science
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• v.31 no.4
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• pp.384-393
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• 2011

Sulfonylurea herbicide-resistant weeds are spreading widely and distributed about 106,951 hectare in paddy rice fields in Korea. Morever all biotype of Scirpus juncoides which were collected at 69 spots all over paddy rice fields in 2008 were identified biotype of sulfonylurea herbicide-resistant. Benzobicyclon is a p-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor, which is absorbed through root and basal stem of weeds so cause bleaching of newly developing leaves. Benzobicyclon was very effective to control Scirpus juncoides, Monochoria vaginalis, sedges and broadleaves weeds, so it have been developed various formulation like a suspension concentrate (SC), a water dispersible granule (WG), a granule (GR) and a DT (tablet for Direct application). During recently 6 years, benzobicyclon-mixtures herbicides have been registered over than 54 products in paddy fields. Herbicidal efficacy by formulations of benzobicyclon and its mixture herbicides were highest in DT, followed by SC and GR. Herbicidal efficacy of the kaolin and $CaCO_3$ carrier of GR was better and stable than that of talc and bentonite carrier. Growth and yield of rice were not affected much by formulations, application rates and rice cultivation methods.

• Weed & Turfgrass Science
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• v.2 no.2
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• pp.131-137
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• 2013

The study was carried out to obtain the basic information on distribution and occurrence of weeds including resistant weeds to sulfonylurea herbicides in paddy fields of Gyeongbuk province. In weed distribution on life cycle, annual weed was occupied by 91.8% and perennials were 8.2%, respectively. In morphological distribution of weeds, broad leaf weeds were 85.7%, sedges was 9.1%, and grass weed was 3.8%, respectively. Sulfonylurea-resistant weeds in paddy fields of twelve regions were widely occurred except for Yecheon region. The six sulfonylurea resistant biotypes occurred in paddy fields of Gyeongbuk province were Lindernia dubia, Eleocharis kuroguwai, Monochoria vaginalis and Ludwigia prostrata. It revealed that occurrence rate and area of sulfonylurea-resistant weeds were about 15.9 % and 22,420 ha in Gyeongbuk province.

• Journal of agriculture & life science
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• v.50 no.4
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• pp.59-71
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• 2016

The occurrence and growth of grass and sedge weed species were investigated in the transplanted rice fields that have different transplanting dates from Apr. 30 to Jun 19 with 10-day interval. The growth and yield of rice plant grown without weed control examined in each plot that has different transplanting dates. Both grass and sedge weeds showed greater plant numbers in the early transplanted plots(Apr. 30 and May 10) than late transplanted plots. Based on the occurring number and dry weight of weeds, the experimental plots were classified into two groups, early group and late group. Weed occurrence and growth were not dramatically different within a group even the occurrence was enhanced as delayed transplanting. Echinochloa spp. that was the most problematic weed showed higher dry weight in early-transplanted field until July, however, the greater dry weight was observed in the late-transplanted plots after August. Sedge weeds including Eleocharis kuroguwai and Scirpus juincoides showed persistently higher value of dry weight in early-transplanted plots than late plots over the experimental period. As the puddling was conducted earlier, emergences of grass and sedge weeds were occurred early and weed growth rate became greater. Therefore, growth and yield of rice that transplanted early decreased more strongly due to the strong suppression by grass and sedge weeds showing the enhanced weed growth rates in early-transplanted plots. Based on the weed growth rate, the adverse effects of grass weeds was maintained for longer period than sedge weeds that showed higher growth rates before heading date of rice plant.

• The Korean Journal of Quaternary Research
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• v.33 no.1_2
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• pp.59-68
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• 2021

The maximum upper limit of seawater inflow can be recognized by the acid-resistant dinoflagellate cysts and salt-marsh pollen encountered from surface samples in the lower reach of Jujin Stream facing Gomso Bay. Based on their relative yield ratio, the downstream area of Jujin Stream could be further subdivided into coastal marine, brackish-upper limit brackish, and freshwater environments. The abundance of dinoflagellate cysts from JJR-41 to JJR-36 sites reflects that this area is a coastal marine. In the section between JJR-35 and JJR-5 sites, dinoflagellate cysts associated with pollen derived from riparian or salt-marsh (e.g., reeds and sedges) appear to reflect the brackish environments. It may be indicated that dinoflagellate cysts appear up to the JJR-4 site, which is the maximum upper limit where seawater flows up to this point at high tide. This analysis is relatively well corresponding to the hypothetical inundation map showing the maximum flooding area where seawater can flow at high tide.

• Korean Journal of Weed Science
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• v.17 no.3
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• pp.269-280
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• 1997

Collated data from the 1995-1996 field surveys of weed seeds buried in the plough layer of peat soil in Selangor district were analysed to assess species-dominance and spatial pattern of distribution of weed seeds based on selected quantitative indices and index of dispersion. Forty five species within 14 families were recorded of which 24 were broadleaves, 12 grasses and 9 sedges. They comprised ca. 53.2, 31.2 and 15.6%, respectively based on total population counts. Total seed population was ca. $8.14{\times}10^7$ seeds/ha within the fast 25cm soil depth. Wide variabilities in population counts were registered among species ranging from < $7.0{\times}10^4$ seeds/ha for Amaranthus gracilis to ca. $5.64{\times}10^6$ seeds/ha for Heteropogon contortus. Seeds of Cleome rutidesperma was the most abundant(ca. $2.347{\times}10^7$ seeds/ha). Difference in seed population counts may be attributed to inherent variation in fecundity, population fluxes, their spatial distribution patterns and the agronomic practices prevailing in the areas of survey. The profile distribution of soil seed banks was skewed within the first 0 - 10cm depth, comprising ca. 69% of the total seed counts. Seed counts in the 10 - 15, 15 - 20 and 20 - 25cm soil profiles were in the order of 17.9, 8.6 and 4.0% of the total populations, respectively. Weed seeds of all species displayed different degree of aggregated pattern of distribution with variance-to-mean ratios of > 1 and Lloyd's mean crowding($m^*$) values from 1.244 for Cyperus iria, Phyllanthus debilis, Phyllanthus urinaria, Scirpus grosses and urinaria lagopodiodes to 9607.7 for Cleome rutidosperma. Lloyd's patch indices(Ip) ranging from 5.1 for Aeschynomene indica to 188.5 for Bracharia reptans were registered. Differences in the VMR, $m^*$ and Ip values among species suggested inter-alia inherent variabilities in their disposal capacity from seed source and different agronomic practices prevailing in the areas surveyed.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.147-156
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• 1997

The survey of weed population in apple orchard was conducted to investigate basic information on weed flora and its ecology at 27 locations in 1996. The weed species observed include 7 species of grasses, 60 species of broadleaves and 2 species of sedges, and the ratio of annual weed vs perennial weed was 64 : 36. Major dominant weed species by frequence were Chenopodium album, Capsella bursa-pastoris, Digitaria sanguinalis, Rorippa islandica, Alopecurus aequalis and Erigeron canadensis. While, on the basis of dry weight, the most dominant weeds were C. album followed by E. canadensis, A. aequalis, R islandica and R indica. The dominant weed species in middle-north Kyeongbuk region were C. bursa-pastoris, C. album, R indica and R islandica, were E. canadensis, Persicaria hydropiper, A. aequalis and Arenaria serpylliforia in Chungbuk region and were A. aequalis, E. canadenris and R islandica in Honam region.

• Weed & Turfgrass Science
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• v.7 no.3
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• pp.191-199
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• 2018

This study was to investigate the occurrence patterns of paddy weeds, their resistance levels to an ALS inhibiting herbicide, and to estimate the areas of resistance in these paddy fields. We used soil collected from 358 paddy fields of Jeonnam province in 2017. Based on their life cycles, weeds were 96% annuals and 4% perennial. Additionally, according to morphological classification, 59% were broad leaves, 28% were sedges and 13% were grasses. Different areas within Jeonnam province contained different numbers and occurrence rates of weed species. However, generally, we observed Lindernia dubia var. dubia, Monochoria vaginalis var. plantaginea, Ludwigia prostrata, L. procumbens, Cyperus difformis, Scirpus juncoides, Eleocharis Kuroguwai, Echinochloa oryzoides, and E. crus-galli var. echinata. We also observed seven weeds resistant to an ALS inhibiting herbicide. They were M. vaginalis, S. juncoides, C. difformis, L. dubia, Ludwigia prostrata, E. oryzoides, and E. crus-galli var. echinata. Although there were differences in the number and occurrence rate of resistant weed species to an ALS inhibiting herbicide among areas in Jeonnam province, the M. vaginalis, C. difformis, and S. juncoides occurred in 23 cities and counties in Jeonnam including Gwangju metropolitan city. Based on the rates (52%) of resistant occurrence to an ALS inhibiting herbicide in Jeonnam province, the area of weed resistant paddy fields was estimated to be 91,543 ha.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.221-228
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• 2011

Weed control is of fundamental importance when planting horticultural crops, particularly during the establishment phase. Weeds compete for nutrients, water and light, and can severely threaten the survival and early growth of newly planted crops. Failure to control weeds represents one of the single most important factors leading to crop loss. Knowledge on the existence of the diversity of weed species in greenhouses is of our main concern in this study in order to develop a most efficient and effective weed control strategies. Sixty-two greenhouses were surveyed in 3 cities and counties of Gyeongnam area in March to October 2009 to investigate the feature of weed occurrence in polyvinyl chloride (PVC) after harvesting of the main crops. Forty-one weed species were identified and classified to 18 families which were composed of 14 annual weeds, 18 summer annual weeds and 9 perennial weeds. On the other hand, broadleaf, grasses and sedges recorded with 30, 7 and 4 weed species, respectively. Asteraceae was the most dominant weed species (9 species) noted followed by Poaceae (7 species), Cyperaceae (4 species), Caryophyllaceae and Brassicaceae (3 species respectively) and other families have 1~2 species. The dominant weed species occurred in the greenhouse based on the summed dominance ratio. These weeds were Digitaria sanguinalis, Cyperus iria, Portulaca oleracea, Rorippa islandica, Mazus japonicas, Cardamine flexousa, and Eclipta prostrata and others. Weed occurrence in the greenhouse after horticultural crops consisted of summer annuals (4 species), winter annuals (3 species), and perennial annuals (1 specie). The dominant species occurred in tilled soil based on summed dominance ratio of weeds were Cardamine flexousa (88.1%), Eclipta prostrate (57.4%) and Portulaca oleracea (55.2%). Comparison of weed occurrence was thoroughly surveyed also in which field without PVC, weed species were Portulaca oleracea (55.2), Eclipta prostrata (57.9%) and Trigonotis peduncularis (25.1%) and field with PVC, the identified weeds were Portulaca oleracea (98.75), Trigonotis peduncularis (49.1%), and Eclipta prostrata (36.8%).