• The Korean Journal of Ecology
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• v.9 no.1
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• pp.1-7
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• 1986

plastochron index was used as a measure for the nitrate reductase activity (NRA) in Amaranthus retroflexus, Chenopodium album var. centrorubrum and Glycine max. The material plants treated with $NO_3$-N had higher NRA than those treated with ${NH_4}^+$-N. High NRA were found in young tissues which have low PI or LPI in both A. retroflexus and C. album. These results indicated that this enzyme decreased with increasing plastochron index of the extracted tissues. High level of NRA was detected in Glycine max leaves at PI 4.0. On the other hand, there were no significant differences for PI among $NO_3$-treated, ${NH_4}^+$-treated and control in both stems and roots.

• The Korean Journal of Ecology
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• v.8 no.3
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• pp.127-132
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• 1985

In this study, the competitive development of leaf in Amaranthus and Chenopodium were invesitgated by the complemented plastochron index. The value of PI for Amaranthus was not varied with competional ratios, while for Chenopodium it was varied. Namely in Chenopodium, the plastochron 1 was increased as competitional combinations, the plastochron 2 was decreased. These results indicated Amaranthus had advantage in competition over Chenopodium. It is surmised that these results were exhibited differences in photosynthetic pathway between Amaranthus (C4 plant) and Chenopodium (C3 plant). The linear patterns were clearly demonstrated by the differences in leaf arrangement between Amaranthus (alternate type) and Chenopodium (opposite type). From these resultss, use of plastochron seems to a useful means of evaluating plat response to various environments.

• Korean Journal of Veterinary Research
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• v.24 no.2
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• pp.173-181
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• 1984

This paper dealt with the histopathological observations of the perirenal edema in pigs and rabbits administered with Amaranthus retroflexus, based on the clinical and pathological observations of the porcine perirenal edema naturally occurred in Korea. The results observed are summarized as follows; In the natural case, clinical signs were trembling, weakness and incoordination of the hindquarters, followed by sternal recumbency, coma and death. Death usually occurred within 24 hours after the signs of illness appeared. In gross findings, the grayish yellow fluid in the perirenal area was observed in each case. In some cases, the amount of fluid in the thoracic and abdominal cavities was increased and the yellowish red color of the hydrothorax and ascites was seen. When the renal capsule was incised, the kidneys were enlarged and congested and petechiae on the cortical surface and blood clots on the capsule appeared. In microscopical findings, there were cloudy swelling, hyaline droplets and necrosis of the convoluted tubules containing proteinaceous casts and a few oxalate crystals. In addition, interstitial and perivascular edema, distention of the Bowman's space and the convluted tubules and hemorrhages were recognized. In the weanling pigs and the adult pig fed various weeds, including Amaranthus retroflexus, Euxolus blitum and Portulaca oleracea, the pigs fed Amaranthus retroflexus appeared clinical signs and pathological findings of perirenal edema usually seen in the pigs of natural cases. In the pigs fed Euxolus blitum or fed Portulaca oleracea, neither clinical signs nor pathological changes were seen. It was regarded that this disease was affected with Amaranthus retroflexus, but there was no sensitivity in the adult pigs.

• Korean Journal of Plant Taxonomy
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• v.44 no.2
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• pp.132-135
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• 2014

A newly naturalized plant, Amaranthus powellii S. Watson was found Jail-dong, Uijeongbu-si, Gyeonggi-do, Korea. This species is native to Southwestern USA and Northern Mexico, and it is also naturalized in worldwide of temperate regions. This species was distinguished from the related species, A. patulus Bertol. and A. hybridus L., by leave blades broadly elliptic, rhombic or lanceolate, petals unequal, without conspicuous green mid-veins, and utricle gradually narrowed toward the stigma. Korean name was given as 'Min-teol-bi-reum' to A. powellii S. Watson, based on the character, it was hairy less than the three related species, A. patulus Bertol., A. hybridus L. and A. retroflexus L., conspicuously. Descriptions for mophological characters, photographs, illustrations and keys to allied taxa were provided.

• Korean Journal of Agricultural Science
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• v.14 no.1
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• pp.38-50
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• 1987

The purpose of this comparative study is to investigate the differences of growth behaviors (height, weight, yield capacities etc.) and germination characters (induced photo-dormancy) among the three different species of Arnaranthus sp. The results obtained are summarized as follows. The growth of the cultivar of A.hypochondriacus was more vigor than that of the wild plant of A.retroflexus during the whole life cycle. The fresh weight, dry weight, yield capacity of A.hypochondriacus were much more higher than those of the others two species (A.retroflexus and A.Cruenthus). There are very different germinability formation and induced dormancy patterns between the cultivar and wild plant during seed formation periods. The cultivar of A.hypochondriacus was not induced primary dormancy in the any seed formation stages but wild plant of A.retroflexus was induced deep true dormancy. We suggested that these differences occured by the sum of different absorption of solar energy spectrum by the different seed colors between the cultivar (white color seed) and wild (black seed). And we confirmed the different absorption spectrum of the three different Arnaranthus sp. seeds.

• The Korean Journal of Ecology
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• v.8 no.1
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• pp.1-5
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• 1985

The plastochron index (PI) provides possibility on studies of the effects of various environmental factors on morphological and physiological development of plants. The PI of Erickson and Michemlini(1957) could be used merely when leaf n is longer an leaf n+1 is smaller than the references length at any time. If both the lengths of leaf n and n+1 are smaller or longer than the reference length, it could not estimated. In this study, the PI of Erickson and Michelini was complemented and the linear patterns according to leaf arrangement was represented, PI is n-(lnLR-lnLn)/(lnLn-lnLn+1). And when both the lengths of leaf n and n+1 are longer than the length of reference, PI is n+1+(ln Ln+1-lnLR)/(lnLn-lnLn+1). The linear model of PI is changed by the various environmental factors and the linear patterns are different according to leaf arrangement. According to leaf arrangement, the equation of the general regression lines is Yin-(i-j)=a-(n-1)(q1+...+qi-1)-(q1+...+qj-1)+rt+$\varepsilon$. Where Y:the logarithmic of the leaf length in question, i:leaf number hang on the one node, n:the number counting from base, q:spacing on the Y-axis, j:0, 1, 2, ..., r:slope, t:time, $\varepsilon$:error.

• Journal of Ecology and Environment
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• v.33 no.4
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• pp.317-323
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• 2010

Nutrient availability is a critical component of agroecosystems, and is relevant to both above- and below- ground interactions. The principal objective of this study was to determine how the cessation of fertilization affects the communities of weeds and soil organisms in a corn/wheat field. Changes in dominant weed species, substrate-induced respiration, and the population density of nematodes and microarthropods were evaluated. Microbial substrate-induced respiration (SIR) and the population density of microarthropods decreased following the cessation of fertilization and were partly correlated with the aboveground weed biomass. The cessation of organic fertilizer application but continuing application of inorganic fertilizer reduced the population density of nematodes. In response to the cessation of fertilization, weed communities were dominated by species with little dependency on fertilization. Amaranthus retroflexus was identified as the most dominant species in the corn field; however, it was replaced by Digitaria ciliaris after the cessation of fertilization. In the wheat field, the cessation of fertilization led to a rapid reduction in the biomass of most weeds, except for Vicia angustifolia, supposedly as the result of symbiotic nitrogen fixation. Additionally, the fact that weed biomass was partially correlated with SIR or the population density of microarthropods may reflect a mutual feedback between soil organisms and weeds. The results indicate that the cessation of fertilization alters communities of weeds and soil organisms through changes in weed biomass and interactions with symbiotic microorganisms.

• Korean Journal of Plant Taxonomy
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• v.35 no.3
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• pp.201-209
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• 2005

Two new naturalized species, Amaranthus hybridus and Crepis tectorum, are reported here. Descriptions and illustrations of the species and comparison of morphology with related species are provided. Amaranthus hybridus was first found at Nanjido, Seoul and is widely distributed in the central and southern part of Korean peninsula. New Korean name is given as "Ginteolbireum". It is well distinguished from the related species, A. retroflexus and A. patulus, by its late flowering time (September to October), sparse hair on the leaves, similar length between tepal and fruit, and long inflorescence without division. Crepis tectorum was first found at the entrance of Weoljeongsa Temple in Pyongchang-gun, Gangwon-do and spreads rapidly to other areas. New Korean name is given as "Nadomindulle".

• Korean Journal of Organic Agriculture
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• v.22 no.2
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• pp.303-319
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• 2014

The study researched germination of the plants and growth of experimented bacteria according to concentration of water extract in order to provide basic data for developing natural agricultural resources by using naturalized plants including Solidago altissima, Amaranthus retroflexus and Sida spinosa. As concentration of water extract increased, most of test plants showed a decrease in relative germinability. Sida spinosa(r=-0.540, p<0.01), Physalis wrightii(r=-0.693, p<0.01), Amaranthus retroflexu(r=-0.724, p<0.01), Solidago altissima(r=-0.728, p<0.01) and Eclipta prostrata(r=-0.779, p<0.01) showed tendency of decrease in relative germinative power in order, respectively. For average germination period, as concentration of the processed group increased, the time for germination increased (r = 0.769, p<0.01) and according to donor plants and test plants, there was a little difference. Also, as concentration of water extract of donor plant, length of above-aerial part(r=-0.587, p<0.01), length of underground part(r=-0.741, p<0.01), fresh weight(r=-0.574, p<0.01) and generation of root hair decreased. An then, for growth of test fungi according to concentration of water extract of donor plants, growths of Botrytis cinerea(r=-0.266, p<0.05), Diaporthe citri(r=-0.323 p<0.01), Colletotrichum gloeosporioides(r=-0.512, p<0.01), Pythiumultimum(r=-0.581, p<0.01) and Rhizoctonia solani(r=-0.806, p<0.01) were repressed in order, respectively. For total amount of content of phenol with herbicidal and Antifungal activities, S. altissima $17.3{\pm}0.5mg/g$, A. retroflexus $13.1{\pm}0.3mg/g$, P. wrightii $12.0{\pm}0.4mg/g$, S. spinosa $9.5{\pm}0.1mg/g$ and E. prostrata L. $4.1{\pm}0.1mg/g$ showed in order, respectively. As these results are summarized, donor plants which were naturalized, have competitive advantage because they release phenolic compounds with allelopathic effect and affect on germination, growth and fungi growth on underground flora compared to native plants and they have eligibility for natural herbicide and germicide.

• The Korean Journal of Ecology
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• v.24 no.5
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• pp.309-313
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• 2001

This research was conducted to test cadmium tolerance by five speices of native herbs for screening cadmium tolerance plant. We examined germination rate, root and shoot growth rate of seedling, fresh biomass of native herbs exposed to cadmium solution for 14 days. Especially, germination rate of Abutilon avicennae and Amaranthus retroflexus was over 90% in all concentration, but germination rate of Aeschynomene indica, Echinochloa crus-galli var. oryzicola and Echinochla crus-galli var. frumentacea began to decrease when they exposed to 15 mgCdSO₄ /L. The higher the Cd concentration, the length of root, shoot grew lower. The fresh biomass of Echinochloa crus-galli var. oryzicola, Echinochla crus-galli var. frumentacea and Amaranthus retro-flexus were not so different from each control, but those of Abutilon avicennae and Aeschynomene indica began to decrese greatly when exposed to 60 mgCdSO₄ /L. EC/sub 50/(Effective Concentration 50%) of Abutilon avicennae, Aeschynomene indica and Amaranthus retroflexus was 44.6∼77.5 mgCdSO₄ /L for root growth, 38.6∼114 mgCdSO₄ /L for shoot growth, 60∼107.5 mgCdSO₄ /L for fresh biomass. Among the native herbs, sensitivity of cadmium ordered as root length > fresh biomass > shoot length. These results indicate that Abutilon avicennae is a tolerant species for cadmium.