• Korean Journal of Weed Science
• /
• v.15 no.2
• /
• pp.131-140
• /
• 1995

This experiment was conducted to test the effect on germination and seedling growth of major industrial crops and weed control potential using alfalfa plant. When dried alfalfa residues were mixed into vermiculite, germination, length of shoot and root of crops, such as Perilla frutescens, Sorghum nevosum, Platycodon grandiflorum and weeds, Digitaria saguinalis, Setaria viridis, Siegesbechia pubescens, Ammaranthus lividus, and Solanum nigrum, were significantly inhibited as the dried residue concentration increased. More than 10% concentration of the dired residue caused 80% germination and growth inhibition. The fresh alfalfa exudation also inhibited the germination and seedling growth of crop, barley, rye, alfalfa, and sesame, and weeds, Echinochloa crus-galli, Siegesbechia viridis, and Portulaca oleracea. The degree of inhibition showed the different response according to the fresh exudation concentration, types of crops and weeds. Generally, as the exudation concentration increased, the germination and seedling growth of crops and weeds inhibited. The exudation of dried residue also exhibited the strong inhibition effect on germination and seedling growth of crops, alfalfa, Platycodon grandiflorum, barley, sesame, rye and weeds, D. sanguinalis, S. pubescens, S. viridis, P. oleracea, E. crus-galli, At the 10% concentrations, S. pubescens, and P. oleracea were not germinated and showed only 15% germination in the S. viridis. From this study, would conclude that alfalfa plant contained water soluble phytotoxic substances which were inhibitory to weeds and crops. This results suggest that alfalfa had some possibility to control some weed species using toxic compounds like natural herbicide.

• Korean Journal of Weed Science
• /
• v.12 no.2
• /
• pp.166-172
• /
• 1992

The identification on blue-queen algae which were collected from paddy rice fields of the whole nation was carried out in 1991. The blue-green algae identified were 20 species in 5 families including 7 species in the Chroococcaceae. 1 species in the Chamaesiphonaceae. 1 species in the Pleurocapsaceae, 6 species in the Nostocaeae and 5 species in the Oscillatoriaceae. Among the blue-green algae, 6 species in 4 genera including Cylindrospernum, Anabaenopsis, Anabaena and Nostoc were characterized by heterocysts concerning with nitrogen fixation capacity. A concentrated population of Oscillatoria spp. induced soil flakes with blue tint in paddy rice fields. The genera. Spirulina and Oscillatoria, showed their specific motility.

• Korean Journal of Weed Science
• /
• v.31 no.1
• /
• pp.112-117
• /
• 2011

A series of experiments was conducted to investigate the herbicidal activity of natural compound chrysophanic acid under the greenhouse condition in 16 weed species. Chrysophanic acid showed non-selective herbicidal activity. While chrysophanic acid exhibited severe injury by foliar treatment, little or no injury was found by the soil treatment. Among the tested weeds, the most effective activity was found in grass and broad leaf weeds, a lower significant difference in herbicidal activity was found in sedge. At early post-emergence, weeds appeared to be very susceptible to chrysophanic acid with $2,000{\mu}g\;mL^{-1}$. The higher the natural compound concentrations, the lower weed growth. At middle post-emergence, weeds appeared to be very effective to chrysophanic acid with $30,000{\mu}g\;mL^{-1}$.

• Weed & Turfgrass Science
• /
• v.5 no.4
• /
• pp.196-202
• /
• 2016

With increasing LM soybean import, the concern about unintentional gene flow from LM soybean to wild soybean and consequential weedy risk has been growing. Therefore, we conducted this study to characterize seed traits including germination of hybrids resulted from gene flow from LM soybean to wild soybean in comparison with their parents, LM soybean and wild soybean. Pollen-donor LM soybean seeds were much greater and heavier (about 15.0 g of 100 seed weight) than F2 hybrid (5.7 g), while pollen-recipient wild soybean and F1 hybrid seeds were smallest and lightest (about 2.5 g). F2 hybrid was brown, intermediate between yellow LM soybean seed and black wild soybean seed. These findings indicate that F1 hybrid seeds show similar characteristics with wild soybean, while F2 hybrid seeds show intermediate color and size between two parents. F2 hybrid seed showed intermediate traits between two parents in germination and dormancy rates, which were 35% and 65%, respectively. LM soybean showed no dormancy, while wild soybean showed greater than 90% dormancy. This finding indicates that F2 hybrid show intermediate characteristics in seed germination with high dormancy trait, suggesting a potential weediness of hybrids resulted from gene flow from LM soybean to wild soybean.

• Weed & Turfgrass Science
• /
• v.5 no.4
• /
• pp.236-240
• /
• 2016

Weeding measures is an important issue for cereal crop because weed is superior to crops in early growth stage and there are not many herbicides applicable to cereal crop. Since the concern about well-being and eco-environmental products are increasing, cultivation with polyvinyl chloride (PVC) is needed. Five treatments included as weed-free, control (not remove weed) and covering with polyvinyl chloride removed 20, 30, 40 DAS (day after seeding). At removing PVC, plant height did not differ depending on the growth stage. However, weed-free plot by weed competition were somewhat short. And, removing PVC accelerated the earlier by 2-3 day than weed-free plot. Soil moisture which removed from the control was higher than 20, 30, 40 DAS and weed-free, and it was kept low by evaporation. The chlorophyll meter of weed-free plot was 34.3, 30 DAS was 40.6 at heading time. Weed-free showed that increased in weed population $300.8g\;m^{-2}$. Weed control value of 20 DAS, 30 DAS, 40 DAS were 86.5%, 84.0% and 74.8%, respectively. In 30 DAS, yield of foxtail millet according to treatment of removing PVC were $355kg\;10a^{-1}$. At weed competition early in 30 DAS, the removing PVC was good for control. Thus, 30 DAS was judged to be suitable.

• Weed & Turfgrass Science
• /
• v.2 no.1
• /
• pp.38-46
• /
• 2013

With increasing environmental issues from synthetic chemical herbicides, microbe-originated herbicides could be a fascinating alternative in current agriculture. We isolated Streptomyces strains that produced herbicidal active metabolite(s) against a grass weed Digitaria sanguinalis. According to the result from 16S rDNA sequence comparison with the close strains, the best isolate (Code name MS-80673) was identified as Streptomyces scopuliridis KR-001. The closest type strain was Streptomyces scopuliridis RB72 which was previously reported as a bacteriocin producer. The optimal culture condition of S. scopuliridis KR-001 was $28^{\circ}C$, pH 7.0 and culture period 4 to7 days. Both of soil and foliar application of the crude culture broth concentrate was effective on several troublesome or noxious weed species such as a Sciyos angulatus in a greenhouse and field condition. Phytotoxic symptoms of the culture broth concentrate of S. scopuliridis KR-001 by foliar application were wilting and burndown of leaves, and stems followed by discoloration and finally plant death. In crops such as rice, wheat, barley, hot pepper and tomato, growth inhibition was observed. These results suggest that the new S. scopuliridis KR-001 strain producing herbicidal metabolites may be a new bio-herbicide candidate and/or may provide a new lead molecule for a more efficient herbicide.

• Korean Journal of Weed Science
• /
• v.11 no.3
• /
• pp.178-186
• /
• 1991

This study was conducted to evaluate the major weeds occurred in direct seeded rice and their compition with rice, and to establish the effective weed control method. The important weeds occurring in dry direct seeded rice were Echinochloa crusgalli, Cyperus amuricus, Rorippa islandica, etc. Among them, Echinochloa crusgalli was the most dominant weed species. In view of the Simpson's dominance index, the maximum number of the weeds was observed at 30 days after seeding, showing 0.26, but decreased as the time passed. In other hand, Simpson's dominance index of weed dry weight increased from 0.09 at 15DAS(days after seeding) to 0.28 at 60DAS indicating that particular weed such as barnyardgrass was dominating the fields. The plant height and the tiller number of rice in the dry direct seeded rice were not greatly affected by the time and duration of competition with weeds, but rice yield was greatly influenced by them. The yield reduction was observed when compition between rice and weeds were initiated at 20 to 40 DAS till the harvesting time. The highest weed control efficacy was observed at the treatment of systematic herbicide application such as soil applied Butachlor followed by Mefenacet/Bensulfuron-methyl/Dymron at 30 DAS after seeding, and soil applied Dimepiperate/Bensulfuron-methyl mixture as a preemergence type gave also an excellent control.

• Weed & Turfgrass Science
• /
• v.7 no.3
• /
• pp.181-190
• /
• 2018

This study was conducted to investigate the occurrence of an acetolactate synthase (ALS) inhibiting herbicide resistant weed on paddy at 289 sites by soil sampling in Chungcheongbuk-Do of Republic of Korea from February to April in 2017. The most dominant weed was Monochoria vaginalis and Echinochloa oryzicola on each city and county. ALS inhibiting herbicide resistant ratio and occurrence area were 80.6% and 28,272 ha, respectively, in Chungcheongbuk-Do which was 3 times than in 5 years ago. The herbicide resistant ratio, Okcheon-Gun was the highest at 93.8%, Chungju-Si, Boeun-Gun, Yeongdong-Gun, Jincheon-Gun and Geosan-Gun were over 80%, Cheongju-Si, Eumseong-Gun and Jeungpyeong-Gun were over 70%. The herbicide resistant area, Cheongju-Si had the largest at 6,957 ha, Chungju-Si was 4,277 ha, Jincheon-Gun and Boeun-Gun was 3,536 ha and 3,282 ha, respectively. By weed, ALS inhibiting herbicide resistant ratio and occurrence area, Monochoria vaginalis was 49%, 17,646 ha, Echinochloa oryzicola 44%, 15,617 ha, Schoenoplectiella juncoides 29%, 10,377 ha, respectively. In all cities and counties of Chungcheongbuk-Do, Monochoria vaginalis and Echinochloa oryzicola are more than 40% resistant to ALS inhibiting herbicides, intensive management is required. The use of sulfonylurea herbicides is increasing, most farmers use herbicides 10 days after transplanting, so management after transplanting is necessary and the occurrence of herbicide resistant weeds should be reduced by alternating herbicide application every year.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.13 no.2
• /
• pp.107-120
• /
• 2005

To study the development of solid waste compost to use sewage sludge and paper mill sludge for reclaiming damage soil in forest, the changes of temperature, moisture, chemical properties, heavy metals and harmful compound during the aerobic decomposition were investigated, and the compost decomposition of final products investigated the round paper chromatography method and G.I(Germination index) value. The results were summarized as follows. Temperature was changed a little during early 5days because of air temperature too low. That was rapidly increased to over $50^{\circ}C$ at 4days after first turning and then decreased gradually fallen to $40{\sim}50^{\circ}C$ at 15days after aerobic decomposition in A and C treatments. The second turning was conducted at 18 days after aerobic decomposition, and then the temperature was little changed. At the compare first with terminal product, The moisture content was decreased all treatments but the change was little in A and B treatments. pH was decreased to below 1 in all treatments. EC was increased to below 5dS/m. The content of total carbon, C/N ratio, $NH_4{^+}-N$ were decreased with 4~7%, below 8 and below 500mg/kg in all treatments, respectively. The content of total nitrogen, $NO_3{^-}-N$, CEC were increased with below 0.5%, below 173mg/kg and over $30cmol^+/kg$ in all treatments, respectively. The content of heavy metals and harmful compound were similar during aerobic decomposition and suited to standard of 가 grade in all treatments. The result of round paper chromatography method and G.I. value, The C treatment concluded well aerobic decomposition. Especially, the G.I. value in C treatment was 64.1 and 66.2 at cabbage and grass, respectively.

• Korean Journal of Weed Science
• /
• v.31 no.3
• /
• pp.279-288
• /
• 2011

To suggest the weed management technique for environment friendly rice cultivation, we investigated occurrence patterns of weeds, the actual condition of weed management, and rice yield at the environment friendly agricultural complex located in Honam and Chungnam regions. The practical performance of weed management was relatively satisfactory in decreasing order of agricultural technique with golden-apple-snail (GAS) > agricultural technique with duck (Duck) > agricultural technique with rice bran (RB) > agricultural technique with soft-shelled turtle (ST). In the rice fields employed by agricultural technique with GAS, the dominant weeds were Echinochloa crus-galli, Ludwigia prostrata, Monochoria vaginalis, Sagittaria trifolia, and Aneilema keisak. However, E. crus-galli, M. vaginalis, L. prostrata, Aeschynomene indica and Bidens frondosa were found as dominant weeds at the fields using the Duck and E. crus-galli, M. vaginalis, L. prostrata, Polyganum hydropiper and Eleocharis kuroguwai at the fields using RB. In comparison of rice yield ($5.2\;MT\;ha^{-1}$) obtained from the conventional cultivation using herbicides, about 93% was reached by Duck, about 91% by GAS, about 92% by RB, and about 78% by ST. When rice qualities obtained from environment friendly rice cultivation were compared with those from the conventional cultivation, the producing rates of perfect kernel, immature kernel, immature opaque kernel, cracked rice, and damaged kernel were lower in the former cultivation, whereas contents of protein, amylose, and fatty acid were similar in the two cultivation methods. The problems found in the environment friendly agriculture were poor plowing and harrowing, carless irrigation management, and geological poor condition as cultivation area with cold water. These have caused severe infestation of weeds, frequent incident of disease and insect pest, and rice lodging. This resulted in reduction of rice yield as high as about 32 to 79% as compared with the conventional cultivation using herbicides.