• Korean Journal of Weed Science
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• v.9 no.2
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• pp.168-173
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• 1989

In the characteristics of intra-specific competition according to bulrush density, the intra-specific competition in plant height began at 5 and 15% per pot in mixed culture and bulrush monoculture, respectively. The intra-specific competition in the shoot began at 5 plants per pot in both mixed culture and bulrush monoculture. The competition in dry matter weight began at 15 plants per pot in monoculture, and at 10 plants in mixed culture. On the rice density, the plant height, and numbers of shoot and dry matter weight in rice were rapidly increased up to 2.6, and 2.5 plants per pot, respectively, And then the increments were slow, The critical intra-specific competition of bulrush with rice was 2.5 to 3 plants per pot in their traits of rice, and especially the number of shoots and dry matter weights per pot showed significant decrements. In the different transplanting time in rice, the plant heights in both rice and bulrush elongated longer in mixed culture than in monoculture. The plant height of bulrush became shorter but the height of rice longer with late transplanting. The ratio of shoot number in rice to the number in bulrush was about 1 : 3 in all plots, and shoot numbers became less by late transplanting. The dry matter weight in both species were decreased by late transplanting, and the decrements were more prominent in bulrush than in rice.

• Korean Journal of Weed Science
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• v.14 no.3
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• pp.212-222
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• 1994

Thiobencarb retarded the growth of new leaves in only barnyardgrass under dry condition while under water condition the shoot growth of broadcast rice, and both shoot and root growth of barnyardgrass was considerably inhibited. Root elongation of rice and barnyardgrass was severely inhibited only under water condition, while that of transplanted rice was slightly inhibited. Inhibition of shoot and root growth in broadcast, drilled rice and barnyardgrass under water condition was much higher than that under dry condition, whereas the inhibition was less in transplanted rice than direct seeded rice. Microscopically, thiobencarb severely inhibited shoot growth and development of barnyardgrass by inducing tubular-like leaves. The cells of the shoot apices of treated barnyardgrass seedling under dry condition was vacuolated and irregularly arranged. Under water condition, leaf primordia of broadcast rice was constricted, barnyardgrass showed tubular-like leaves, inhibited apices elongation and vacuolated cells(visually lack cytoplasm).

• Korean Journal of Weed Science
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• v.12 no.2
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• pp.89-101
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• 1992

In this study, various physiological and biochemical experiments were conducted to know whether the selectivity between rice and barnyardgrass treated with bleaching herbicides containing diphenyl ether compounds was also partly based on their basic physiological proterties such as peroxidation ability, membrane stability or antioxidant system. It seemed to be partly based on the differences of their physiological characteristics that barnyardgrass was commonly more susceptible to most of the bleaching herbicides than rice. The scenescence of intact leaf segment was more rapid in barnyardgrass than in rice, indicating that barnyardgrass is weak at early stage. Also pigment metabolic ability, antioxidant enzyme activities(peroxidase, catalase, superoxide dismutase, glutathione reductase) and antioxidant content (tocopherol, ascorbic acid, glutathione, carotenoids) were lower in barnyardgrass on the basic of fresh weight. However, lipoxygenase activity and the content of unsaturated fatty acid which is vulnerable to oxygen radicals were higher in barnyardgrass, suggesting that barnyardgrass seedling bave a properties easy to be peroxidized. The differences of PPIX (protoporphyrin IX) or carotenoid content, which are the primary substances inducing herbicide activity, were not related to the selectivity between rice and barnyardgrass.

• Korean Journal Plant Pathology
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• v.12 no.1
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• pp.58-65
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• 1996

한국의 수도 재배 지대에서 문제가 되는 다년생 논잡초 올방개에 자연상태에서 기주특이적으로 기생하여 올방개 줄기를 고사시키는 병원균인 Epicoccosorus nematosporus를 우리나라에서 처음으로 분리, 동정하였으며, 이 병을 올방개 지문무늬병(Finegerprint stem blight disease of water chestnut)으로 명명하였다. 분생포자는 분생자층 위에서 형성이 되며 무격막, 단핵이며, 44.5~72 $\mu\textrm{m}$ 크기의 양끝이 뾰족한 선충 모양이다. 갈색의 병반상에서 흑색의 분생자층은 발달하여 특이한 지문무늬를 형성하는 것이 특징이다. 이 병균은 전국의 올방개가 자라는 논에서 분포하며 매년 발생한다. 온실 접종시 초기의 병징은 접종후 4~5일만에 바늘끝 모양의 회흑색의 반점으로 나타나며 시간이 경과하면서 병반은 급속도로 진전하여 접종후 10~15일 정도 후 약 10mm 내외의 갈색병반이 형성이 되어 올방개 줄기를 감싸고 그 줄기 전체는 고사하게 된다. 분생포자 현탁액(3.2$\times$10\ulcorner conidia/ml)을 온실 조건하에서 분무접종 하였을 때 20일 이내에 약 78.0~93.3% 정도의 고사율을 나타내었다. 올방개 지문무늬병균의 분생포자 현탁액(3.2$\times$10\ulcorner conidia/ml)을 온실 조건하에서 벼 등 31개 작물과 피 등 15개 잡초의 유묘에 접종하였을 때 올방개를 제외한 어떤 식물에도 병원성이 없었다.

• Weed & Turfgrass Science
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• v.3 no.2
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• pp.86-94
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• 2014

Survey was carried out in paddy fields to investigate the dominance of weed species and weed occurrence on 200 fields of southern Gyeonggi region in Korea during the year 2013. We observed 3 species of grass, 5 species of sedge, and 11 species of broadleaf and other weeds. The most dominant weed species was Eleocharis kuroguwai, followed by Echinochloa crus-galli, Sagittaria trifolia, Monochoria vaginalis, Scirpus juncoides and Bidens tripartita. The dominance value of E. kuroguwai and B. tripartita decreased compared to the survey results performed in 2005 but that of M. vaginalis, S. juncoides, S. trifolia and E. crus-galli increased. Weed occurrence increased from 2.83 g in 2005 to 3.51 g in 2013 based on weed dry weight per $m^2$. Occurrence ratio of annual weeds to perennial weeds changed from 45.2% : 54.8% in 2005 to 45.8% : 54.2% in 2013. If we analyze dominance of weed species based on the rice transplanting timing, E. kuroguwai and E. crus-galli were the most dominant weed species at mid-May transplanting, and M. vaginalis and S. juncoides were the most dominant weed species at late- May transplanting, and M. vaginalis and E. kuroguwai were the most dominant weed species at early-June transplanting. Since paddy weeds resistant to sulfonylurea herbicides are expected to be continuously increased, the regular monitoring of their occurrence and efficient control methods should be considered in future.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.853-858
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• 2011

The cultivation methods are important for determining crop yield of green manure. The effect of cultivation methods of green manure crops (GMC) on biomass and rice yield was investigated. This experiment was conducted at Sinheung series (fine loamy, mixed, nonacid, mesic family of Fluvaquentic Endoaquepts from Oct. 2007 to Oct. 2008 at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Korea. Seven GMC (hairy vetch, barley, Chinese milk vetch, rye, crimson clover, oats, rattail fescue) were cultivated and incorporated on paddy soil by broadcasting before rice harvesting (BBRH) and partial tillage seeding (PTS). Among the three leguminous GMC, the biomass and N production were the highest at the hairy vetch of PTS. Among the four gramineae GMC, the biomass and N production tended to be higher in the rye of BBRH and barley of PTS. The C/N ratio (56.5~74.2) of rye was high compared with hairy vetch (14.1). Among the GMC, the incorporation of hairy vetch increased $NH_4$-N contents in rice paddy soil at 14 and 42 days after transplanting. These results showed that hairy vetch had no significant to rice yield compared with conventional fertilization. Therefore, hairy vetch seems to be the most efficient green manure crop as an alternatives to chemical N fertilizer in the central regions of Korea.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.122-134
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• 2010

We investigated the levels of resistance and accumulation of terapyrroles, reactive oxygen species, lipid peroxidation, and antioxidative enzymes for reasons of growth reduction in herbicide-transgenic rice overexpressing Myxococcus xanthus, Arabidopsis thaliana, and human protoporphyrinogen oxidase (Protox) genes. The transgenic rice overexpressing M. xanthus (MX, MX1, PX), A. thaliana (AP31, AP36, AP37), and human (H45, H48, H49) Protox genes showed 43~65, 41~72 and 17~70-fold more resistance to oxyfluorfen, respectively, than the wild type. Among transgenic rice lines overexpressing Protox genes, several lines showed normal growth compared with the wild type, but several lines showed in reduction of plant height and shoot fresh weight under different light conditions. However, reduction of plant height of AP37 was much higher than other lines for the experimental period. On the other hand, the reduction of plant height and shoot fresh weight in the transgenic rice was higher in high light condition than in low light condition. Enhanced levels of Proto IX were observed in transgenic lines AP31, AP37, and H48 at 7 days after seeding (DAS) and transgenic lines PX, AP37, and H48 at 14 DAS relative to wild type. There were no differences in Mg-Proto IX of transgenic lines except for H41 and H48 and Mg-Proto IX monomethyl ester of transgenic lines except for MX, MX1, and PX. Although accumulation of tetrapyrrole intermediates was observed in transgenic lines, their tetrapyrrole accumulation levels were not enough to inhibit growth of transgenic rice. There were no differences in reactive oxygen species, MDA, ALA synthesizing capacity, and chlorophyll between transgenic lines and wild type indicating that accumulated tetrapyrrole intermediate were apparently not high enough to inhibit growth of transgenic rice. Therefore, the growth reduction in certain transgenic lines may not be caused by a single factor such as Proto IX, but by interaction of many other factors.

• Applied Biological Chemistry
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• v.38 no.1
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• pp.90-94
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• 1995

Post emergence herbicidal activities$(pI_{50})$ of X-substituted phenylvinylsulfone derivatives(S) in-vivo against rice(Oryza sativa L.), Barnyard grass(Echinochloa crus-galli) and Pickerelweed(Monochoria vaginalis Presl) were measured by the pot test under paddy conditions. The (S) showed herbicidal symptom rapidly with lower activity(average $pI_{50}=2.0$) as proherbicide, which was excellent tolerance to rice. The structure activity relationships(SAR) were analyzed using such a physicochemical parameters as hydrophobic$({\pi})$ and molecular orbital(MO) quantity by the multiple regression technique, and discussed with quantum pharmacology. The herbicidal activities were related to the hydrophobic$({\pi})$ effect of X-substituent and orbital(HOMO & LUMO) energy. In case of Pickerelweed, the effect was rationalized by parabolic function of ${\pi}$ constant, where the optimal value of ${\pi}$ was 1.10. An increase in hydrophobicity and negative orbital energy by the electron attracting X-substituent may contribute to the herbicidal activity. Based on results proposed from SAR analysis, the mode of herbicidal action could be assumed.

• Korean Journal of Weed Science
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• v.17 no.4
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• pp.421-430
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• 1997

This experiment was conducted to detect the presence of allelopathic substances in the leaves of Ginkgo biloba L. Water extracts from G. biloba leaves which collected at different season markedly inhibited the germination and growth of O. sativa, E. crus-galli, D. sanguinalis, and L. sativa, indicating the presence of biological substances. Linolenic and palmitic acid were the major fatty acids of G. biloba leaves. The biochemical substances such as salicylic arid, p-coumaric acid, catechol, hydroquinone, orchinol, ferulic acid, phloroglucinol, and umbelliferone etc., belonging to the phenolic, compounds were, detected in a large amount, which may be responsible for exhibition inhibitory effects. The common phenolic compounds were detected in the early-harvested and late-harvested G. biloba leaves were salicylic and p-coumaric acid. All these compounds were related to the allelopathic activities in G. biloba leaves.

• Korean Journal of Weed Science
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• v.32 no.1
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• pp.25-34
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• 2012

Characteristics related to grain quality and physiochemical components such as mineral, total amino acid, free amino acid, and free sugar composition were investigated in Protox inhibitor resistanttransgenic rice (MX, PX, and AP37) and its nontransgenic counterpart (WT). Head rice, palatability, protein, and whiteness (except for MX and AP37) of milled transgenic rice were high or similar to those of the non-transgenic counterpart. Immature rice, unfilled grain, and cracked kernels (PX and AP37) of milled transgenic rice were lower than those of its non-transgenic counterpart. However, there were no significant differences in damaged grain between the transgenic rice lines and its counterpart. Potassium content in PX and copper contents in PX and AP37 were only low compared with their non-transgenic counterparts, but other mineral contents in transgenic rice lines were high or showed no significant differences compared with non-transgenic counterparts. Contents of most total amino acid composition in transgenic rice lines were high or similar to those in non-transgenic counterparts, but the content of isoleucine in AP37 was only low compared with its non-transgenic counterpart. On the other hand, free amino acid, leucine and tyrosine in PX and AP37, and total free amino acid in PX were low compared with their non-transgenic counterparts. However, the content of free amino acid in other kinds in transgenic rice lines were similar to those in their non-transgenic counterparts. Contents of sucrose in MX and PX were low compared with non-transgenic counterpars, but contents of fructose, glucose, and maltose in transgenic rice lines were high or similar compared with their non-transgenic counterparts. This results indicated that Protox genes had no negative affect on the nutritional composition of rice.