• Journal of Crop Science and Biotechnology
• /
• v.10 no.2
• /
• pp.79-85
• /
• 2007

Rice bran application just after transplanting has been increasingly practiced as an herbicide-substitute for organic rice production in Korea. However, this practice is frequently reported to be unsatisfactory in weed suppression. An experiment with five treatments that combines flooding depth, rice bran application dose, and herbicide treatment was done in the paddy field to evaluate whether rice bran application under deep flooding can lead to a successful weed control in compensation for the single practice of rice bran application. Rice bran was broadcasted on the flood water surface just after deep flooding of 8 to 10cm that was started at seven days after transplanting. In the shallow flooding plot without herbicide six weed species were recorded: Monochoria vaginalis, Echinochloa crus-galli, Ludvigia prostrate, Cyperus amuricus, Aneima keisak, and Bidens tripartite. Among the first four dominant weed species, deep flooding significantly suppressed the occurrence of Echinochloa crus-galli and Cyperus amuricus while did not suppress the occurrence of Monochoria vaginalis and Ludwigia prostrate. On the contrary, rice bran application under deep flooding suppressed significantly Monochoria vaginalis and Ludwigia prostrate while didn't exert an additional suppression of Echinochloa crus-galli and Cyperus amuricus compared to deep flooding alone. Rice bran application and deep flooding suppressed complimentarily all the six weed species to a satisfactory extent except for Monochoria vaginalis of which suppression efficacy was 31.9%. Deep flooding reduced the panicle number substantially by inhibiting the tiller production, increased the spikelet number per panicle slightly, and leaded to a lower rice grain yield compared to shallow flooding with herbicide. Rice bran application under deep flooding mitigated the panicle reduction due to deep flooding, increased the spikelets per panicle significantly, and thus produced even higher grain yield in the rice bran application of 2000kg $ha^{-1}$ as compared to the shallow flooding treatment with herbicide. In conclusion, this practice applying rice bran under deep flooding would be promising to be incorporated as an integral practice for an organic rice farming system.

• Weed & Turfgrass Science
• /
• v.4 no.4
• /
• pp.295-307
• /
• 2015

Surveys of weed species in paddy fields were conducted to identify weed occurrence on July 2013. Total 237 sites of paddy fields in 9 City/Gun, Jeonnam Provinces in Korea were investigated. From the survey, 45 weed species in 18 families were identified and classified to 33 annuals and 15 perennials. Based on the occurrence ratio, the most weed species belonged to Poaceae (9 species) and 8 and 4 weed species belonged to Cyperaceae and Scrophulariaceae, respectively. These 21 weed species in the most four families accounted for 46% of total weed occurrence. The most dominant weed species in Korean paddy fields were Echinochloa spp. (18.5%), followed by Monochoria vaginalis (12.3%), Lemna perpusilla (8.2), Eleocharis kuroguwai (5.2%) and Scirpus juncoides (5.2%). The most dominant weed species in machine transplanting paddy fields were Echinochloa spp. (14%), followed by Monochoria vaginalis (12%) and in water seeded rice paddy fields were Echinochloa spp. (25%), followed by Monochoria vaginalis (11%). This information could be useful for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods in paddy fields.

• Weed & Turfgrass Science
• /
• v.6 no.4
• /
• pp.345-349
• /
• 2017

Herbicides are important weed control tools for increasing crop yields and the efficiency of crop production. As the use of herbicides increases, the occurrrence of herbicide-resistant weeds has been an increaing problem. In Korea, since the first occurrence of acetolactate synthase (ALS) inhibitor resistant Monochoria korsakowii was reported in the Seosan reclaimed paddy field in 1998, resistance has been reported in 14 weed species, including Echinochola spp. and their populations are gradually increasing. The objective of this study is to investigate the nationwide occurrence of ALS and Acetyl-CoA Carboylase inhibitor resistant Echinochloa spp. in Korea. In 2013, 2014, and 2015, we collected 594 accessions of Echinochloa spp. in Korean rice fields except for Jeonnam and Chungbuk provinces. They were then treated with the recommended rates of penoxsulam and cyhalofop-butyl. We harvested seeds from 45 accessions of E. oryzicola in the case of cyhalofop-butyl treatment. Also, 44 and 46 accessions of E. oryzicola and E. crus-galli survived and their seeds were harvested after penoxsulam treatment. Twenty accessions of E. oryzicola survived from both herbicides inferring possible multiple resistance. Two accessions out of 20 inferred from possible multiple resistance survived after cyhalofop-butyl treatment at a dose of $500ga.i.ha^{-1}$. Seeds of herbicide resistant populations will be provided and utilized for further research.

• Korean Journal of Weed Science
• /
• v.9 no.2
• /
• pp.108-115
• /
• 1989

An experiment was carried out at the International Rice Research Institute in 1987 to understand the seed germination and seedling development of rice and Echinochloa species. The percentage germination of rice cultivars(IR64 for lowland-type and UPLRi-5 for upland-type) was extremely high(>90%) regardless of temperature while that of Echinochloa species ranged from 10 to 80% depending on the species. Among these, E. crus-galli ssp. kispidula had the lowest germination with less than 20% at the high temperatures ($30^{\circ}C$, $35^{\circ}C$) and about 45% at the low temperature ($25^{\circ}C$). Original seed weight gradually decreased with time white root and shoot weight increased for both rice and Echinochloa species. However, increase in root and shoot weight did not compensate for the loss of stored carbohydrate during the experimental period. The root of E. glabrescens grew from the seed on the opposite side of the shoot while for rice it grew from the same side of the seed as the shoot. Echinochloa glabrescens had a leaf blade-like expanded first leaf that contained chlorophyll while rice had an incomplete first leaf that had no leaf blade and no chlorophyll. Due to this E. glabrescens could grow independently 2 to 3 days earlier than rice.

• Korean Journal of Plant Taxonomy
• /
• v.37 no.4
• /
• pp.545-563
• /
• 2007

The investigated vascular plants of Dok-do island were confirmed that consisted of 46 species, 1 subspecies, 1 varieties in total of 48 taxa growing spontaneously. 1 taxa of Pteridophyta, 36 taxa of Dicotyledon and 11 taxa of Monocotyledon identified. In 48 identified taxa in this study, total 13 taxa included Orobanche coerulescens Stephan, Fallopia sachalinensis (F. Schmidt) Rouse Decr., Lonicera insularis Nakai identified according to the Korean plant taxa for environmental assessment. Planting species were about 10 taxa included Pinus thunbergii Parl., Hibiscus syriacus L. and etc. Four species confirmed in this study such as between Chenopodium virgatum Thunb. and Chenopodium album L., Echinochloa crusgalli (L.) P.Beauv. and Echinochloa crusgalli var. oryzicola (Vasinger) Ohwi. were doubt on identification in taxonomic entity due to morphological characteristics. The dispersion type of Do-kdo plants were anemochore 31 taxa, zoodchore 8 taxa, hydrochore 2 taxa and the others by artificial means.

• Korean Journal of Weed Science
• /
• v.7 no.3
• /
• pp.247-256
• /
• 1987

The ability of three Echinochloa colona (L.) Link ecotypes to compete with rice (Oryza sativa L.) was evaluated. For all the ecotypes, E. colona was shorter and produced less leaf area and dry matter than rice at 15 days after seeding (DAS), whereas the reverse was observed from 30 to 60 DAS. Neither E. colona nor rice tillered during the first 15 DAS, but E. colona had greater accumulative tiller length than rice from 15 DAS. Rice absorbed more nitrogen than E. colona at 15 DAS. E. colona absorbed greater amounts of nitrogen, phosphorus, and potassium than did rice between 30 and 60 DAS and increase in its density decreased the nutrients uptake of rice. Differences in the competitive ability of the ecotypes were related to the growth characteristics of the ecotypes and the period of competition between the two species. At the early growth stages the Pangasinan ecotype, which increased plant size rapidly and had a shorter life cycle, was more competitive against rice than the Leyte and South Cotabato ecotypes, which had a longer vegetative growth period. However, the reverse was observed at the later growth stages of the ecotypes.

• Weed & Turfgrass Science
• /
• v.2 no.2
• /
• pp.164-169
• /
• 2013

Alternatives to commercial chemical herbicide are currently being searched and tested due to the numerous adverse effects of commercially available herbicides to the environment. Barnyardgrass (Echinochloa crusgalli) is an important weed species around the world, especially in paddy rice fields. This study focuses on the favorable effects of mixing pyroligneous acids with commercial liquid herbicides. Seedlings were transplanted and grown under greenhouse conditions. The effect of treatment time or leaf-stage on herbicide-pyroligneous acid efficacies was checked, coupled with isolation and quantification of biochemical compounds. Results revealed that herbicide treatment at early post emergence (2~3 leaf stage) of Echnochloa crus-galli leads to effective control. Both liquid herbicides affected fatty acid, protein, and amino acid syntheses as reflected on their contents. The influence of wood vinegar (WV) or rice vinegar (RV) on these compounds was not thoroughly verified due to lack of information on the pyroligneous products. We observed that mixing WV or RV with BCB (bentazone + cyhalof-butyl) gives more favorable results than BUC (butachlor + clomazone), mixed with WV or RV. The result would indicate the potential of mixing pyroligneous acid in reducing herbicide application rate.

• Plant Resources
• /
• v.1 no.1
• /
• pp.43-48
• /
• 1998

The objective of this study was to determine how elevated $CO_2$ and temperature affected early growth and competition between direct seeded rice (Oryza sativa) and a common paddy weed (Echinochloa glabrascens). By using temperature gradient chambers. Rice and E. glabrescens were grown for 5 weeks at ratios of 1:0. 3:1 and 0:1 at three temperatures ($16.4^{\circ}C,\;19.8^{\circ}C,\;and\;22.2^{\circ}C$) and either in ambient (361ppm) or elevated (566ppm) $CO_2$. For both species. elevated $CO_2$ had no effect on mainstem leaf number while air temperature had a slight positive effect which was greater in E. glabrescens than rice. With elevated $CO_2$ rice leaf area index and plant height increased alightly in all species combinations but no increases were observed for E. Glabuescens. For rice in all combinations. elevated $CO_2$ tended to increase the rot and total biomass much more than any other growth parameters: the increases in root and total biomass resulting from elevated $CO_2$ ranged from 16% to 40%. depending on air temperature. At the lowest temperature, the decrease in rice biomass in combination with E. glabrescens was significantly greater at elevated $CO_2$ (18%) than ambient $CO_2$ (3%). At the highest temperature, however, the decrease in rice biomass at elevated $CO_2$ (22%) was less than that at ambient $CO_2$ (36%). The competitive ability of rice as measured by the decrease in biomass when grown in combination with E. glabrescens depended strongly on root growth and/or allocation. These results suggest that at higher temperatures elevated $CO_2$ could enhance the competitive ability of direct seeded rice during early growth. However, at lower temperatures. the competitive ability of E. glabrescens seems to be greater.

• Korean Journal Plant Pathology
• /
• v.1 no.1
• /
• pp.38-43
• /
• 1985

A bacterial brown stripe disease new to Korea was noted for the first time on rice seedlings grown in the nursery pots and in a field nursery. Artificial hypodermic injection and pricking inoculation with isolates obtained from lesions of naturally infected plants produced symptoms similar to those occurring under natural condition. Among eleven species of ten genera of gramineous plants Echinochloa crusgalli, Digitaria sanguinalis and Setaria viridis were the new hosts for the pathogen. On the basis of bacteriological and biochemical tests of isolates from infected rice seedlings, the causal bacterium is considered to be Pseudomonas avenae Manns.

• Applied Biological Chemistry
• /
• v.37 no.6
• /
• pp.522-525
• /
• 1994

Fourteen 2-(1-anilinobutylidene)-5,5-dimethyl-3-hydroxy-2-cyclohexen-1-ones were prepared by condensation of 2-butanoyl-5,5-dimethyl-3-hydroxy-2-cyclohexen-1-one with various substituted anilines in good yield. These were tested for herbicidal activity against six different submerged paddy weed species. Most compounds showed significant activity against Echinochloa crus-galli and Sagittaria pygmaea with excellent tolerance to rice.