• Korean Journal of Weed Science
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• v.30 no.1
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• pp.34-42
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• 2010

Competitive ability, allelopathy, made the common ragweed (Ambrosia artemisiifolia var. elatior ) one of the most dangerous weeds in Korea. The aim of this research was to evaluate the role of common ragweed as test species under laboratory bioassay and glasshouse conditions. Inhibition effect of the leaf extract was higher than that of stem and root parts extracts on germination and seedling growth of weeds. The 5% concentration of leaf extract of common ragweed inhibited the germination rate of Echinochloa crus-galli, Digitaria sanguinalis and Cyperus microiria by 68.3, 74.6 and 87.3%, respectively, as compared to the control. Generally, increasing incorporation concentration inhibited seedling growth of weeds. Incorporation of 5% common ragweed residue significantly reduced the plant length of E. crus-galli, D. sanguinalis and C. microiria by 48, 63 and 68%, respectively, as compared to the control. Also, the values of dry weight were 72, 78 and 71%, respectively. Contrarily, the emergence rate of soybean and corn was not affected by the incorporation of 5% concentration of common ragweed residue. However, the dry weight was inhibited by 37 and 28%, respectively. These results suggest that common ragweed had the ability to control some weed species using toxic compounds like natural herbicide.

• Korean Journal of Weed Science
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• v.9 no.2
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• pp.123-129
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• 1989

1) Optimum temperature was $15^{\circ}C$ for C. bursa-pastoris, $20^{\circ}C$ for C. album, $30^{\circ}C$ for P. oleracea, A. lividus, E. crus-galli, D. sanguinalis, and 4 showed wide range of germination temperature. 2) Emergence of C. bursa-pastoris, and C. album was best at $14.8^{\circ}C$ of soil temperature, E. crus-galli at $23^{\circ}C$, E. indica, A. lividis and P. oleracea at $27.1^{\circ}C$ and A. retroflexus and D. sanguinalis at $31.1^{\circ}C$. 3) A. retroflexus and P. oleracea started to germinate at 30% water absorption stage and A. lividus, C. album, S. viridis, and D. sanguinalis at 40% and E. indica at 70%. 4) Germination of weed species was decreased as PEG 6000 induced osmotic potential lowered. C. album, P. oleracea, D. sanguinalis, A. lividus, and Solanum nigrum were germinated at -5.0 bar osmotic potential and C. album and P. oleracea were germinated at -7.0 bar.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.265-272
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• 1988

This experiment was carried to investigate the germination pattern in relation to temperatures and lights, and the emergence pattern in relation to seeding depths, lights and the alpha amylase activity of Youngia sonchifolia, Lactuca indica var. laciniata, Ixeris dentata var. albiflora and Ixeris polycephala. In Y. sonchifolia, the optimum germination temperature was $25^{\circ}C$, the optimum seeding depth to emerge was 0 mm and it could emerge in 0-5mm. In L. indica var. laciniata under cool storage, the optimum germination temperatures were $19^{\circ}C-28^{\circ}C$, the optimum seeding depth was 5mm and it could emerge in 0-20mm. In L. indica var. laciniata under room storage, the optimum germination temperature was $25^{\circ}C$ the optimum seeding depth was 5mm and it could emerge in 0-10mm. In I. dentata emerge was and 0mm and it could emerge in 0-5mm. In I. polycephla, the optimum temperatures were $16^{\circ}C-19^{\circ}C$, the optimum seeding depth to emerge was 0mm and it could emerge in 0-5mm. The alpha amylase activity was lower Y. sonchifolia, L. indica var. laciniata and I. dentata var. abiflora than barley cultivar Dongbor#1. And the increased pattern of alpha amylase activity was likely to it of germination rate.

• Korean Journal of Weed Science
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• v.8 no.1
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• pp.15-22
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• 1988

In this experiment, interactions between light and other factors such as chilling, alternating temperature, moisture, content, oxygen, and seed coat which affect germination of Oenothera lamarckiana Ser. seed were investigated to study the physiological effects of light on the germination. Light induced the initial stage of seed germination before radical protrusion by affecting embryo rather than seed coat even under anaerobic condition or low water potential (-18 bars). This light effect on germinability of seed was suppressed by blue light irradiation and the effect was increased with increment of blue light intensity and irradiation time. However, the blue light effect was reversible. Chilling, alternating temperature, softening of seed coat and light showed promotive interaction in the induction of seed germination. Irradiation of filtered light (monochrome), however, reduced chilling effect on germination. Hydrogen-ion concentration and gibberellic acid treatment had no effect on light or dark germination.

• Korean Journal of Weed Science
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• v.7 no.2
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• pp.130-138
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• 1987

The effects of light and storage conditions on the germination of Oenothera lamarckiana were investigated. Germination was induced by red light, but inhibited by green, blue or infrared. No germination occurred in the dark. Radicle was more photosensitive than other parts of the seed. The rate of germination was proportional to increase in Light intensity ranging from 10 to 3000 Lux. Photosensitivity occurred 6 hrs after water imbibition of air-dried seeds. Maximum photosensitivity was detected 1-2 days after seeding under the light condition at 300 Lux. Germination was almost completed 3 days after seeding. When seeds stored in the chilling and wetting condition were kept at constant temperature in the dark, they germinated well. Air-dried seeds, however, didn't germinate. Whereas, the seeds which kept at alternating temperature had the tendency that seeds stored at room temperature (25$^{\circ}C$) germinated better than those stored at low temperature (4$^{\circ}C$).

• Korean Journal of Weed Science
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• v.16 no.3
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• pp.200-209
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• 1996

It is assumed to be an efficient method for keeping a germinability of weed seeds as long as possible, if a secondary dormancy is not induced by transferring the seeds of which dormancy was broken in wetting condition into drying condition. To investigate its validity, two experiments were carried out on seeds of 9 weed species ; to find out the most effective storage condition in breaking the dormancy of each weed species and to know whether there is a decrease in the germinability by transferring into drying storage condition. The dormancy of Chenopodium album and Stellaria aquatica was released well under the drying condition, but that of Echinochloa crus-galli var. oryzicola by soaking in water. Other weed species were released from dormancy by storage in wetting condition. When the seeds stored in the wetting or soaking condition, are air-dried and then restored at room or low temperature, a decreasing tendency of germinability which might cause a trouble in using them practically, was not observed except on the seeds of Persicaria vulgaris. In the case of Persicaria vulgaris, the low germination since 3 month-storage seemed not to be caused by drying, because a decrease of its germinability was observed with increasing storage period in all of the storage conditions. In contrast, high germination was induced as the seeds of Echinochloa crusgalli var. oryzicola, which were not germinated during the storage in low temperature and wetting condition, were transferred into the room temperature and drying condition. These results suggest that this approach can be one of the efficient methods for keeping a good germinability as long as possible in most weed seeds.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.749-758
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• 2023

An understanding of safety problems pursuant to environmental release of GM (Genetically Modified) crops is considered important. Among the recognized safety problems, the possibilities of weediness and ecosystem invasion are constantly being validated. We herein compared the growth characteristics and germination rate of soybeans formed by hybridization with vitamin A-enhanced soybeans carrying an introduced gene that increases β-carotene content. We also examined overwintering, survival, and weed competitiveness to evaluate hybrid ecological impact on long-term unmanaged cultivatable land. These studies revealed that the hybrid soybeans exhibited intermediate growth characteristics and germination rate compared with the vitamin A-enhanced soybeans and wild soybeans, or exhibited traits similar to those of the maternal strain. Overwintering experiments were conducted by planting seeds at depths of 0, 5, 10, and 20 cm and recovering them after three or five months. After five months, all seeds at depths more than 5 cm lost viability. Among seeds recovered after three months, only wild soybeans retained viability at depths of more than 5 cm. Survival and weed competitiveness were assessed by sowing each type of seed and performing no irrigation, or pest or weed control. Quantitative assessment of numbers of individual soybean plants that appeared in the experimental plot revealed that all plants germinated after sowing, but only wild type plants survived overwintering. These studies suggest that both GM soybeans and hybrid soybeans cannot survive in uncultivated land even if they are released into the environment, which indicates less possibility of ecosystem invasion and weediness.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.2
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• pp.68-75
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• 1991

A series of tests was carried out to determine the purity and germination of pasture plant and forage crop seeds imported in 1986 and 1987 at the grassland and forage laboratory, College of Agriculture, Seoul National University, Suweon. At the same time, the results obtained were compared with the National Livestook Cooperatives Federation(NLCF1's seed standards as a guide for determining seed quality. 1. The germination percentages of Potomac orchardgrass, Fawn tall fescue, Aquila Ky bluegrass and California ladino clover among grasses and legumes tested were lower than those of the N1,CF's standards, but the germination percentages of forage crops were higher than those of the NLCF's standards. 2. The purity of Potomac orchardgrass and Aquila Ky bluegrass were relatively lower than those of the NLCF's standards. 3. The percentages of other crop seeds in Potomac orchardgrass, Fawn tall fescue, Aquila Ky bluegrass and Cayuse oats were lower than those of the NLCF's standards. 4. Percentage of inert matter in the seeds was lower compared with the NLCF's standards except Akela ' forage rape. 5. The seeds of Potomac orchardgrass, NK 367 sorghum hybrid and sorghum x sudangrass hybrids such as NC+855, G83F and TE Haygrazer were contaminated with one or more weed seeds. Rumex spp. was by far the most common weed in the seeds imported. The other weeds occurred at a low level were Rumex acestosella, Senecio jacobaea, Cirsium arvense and Cuscicta spp. 6. There were many variations in 1,000 seed weight among different species. A thousand seed weight of Aquila Ky bluegrass was 0.263g, but that of Tetrone Italian ryegrass, Akela forage rape and Pioneer 3160 sorghum x sudangrass hybrid was 3.875, 3.476 and 242.4578, respectively. 7. According to the fluorescence test of ryegrass seed, Tetrone Italian ryegrass was known as a true annual type, but an unknown cultivar produced in Cheju was contaminated with 6% of perennial ryegrass seed.

• Korean Journal of Weed Science
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• v.12 no.1
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• pp.52-60
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• 1992

There was no significant difference in the final germination percentages(Experiment 1-3) as affected by sunflower root exudates between the control and the treated for the test species. In general(Experiment 1), however, germination onset was delayed the treated bottles. Germination rate was, also, reduced for both radish(Raphanus sativus L.) and rice(Oryza sativa L.). Therefore, the germination index was low in the treated bottles but germination gradually increased with time in the greated bottles in all test species so that the final germination percentages were similar between treatments. The root exudates of sunflower had significant inhibitory effects(Experiment 1-3) on the lengths of the shoots and roots of all the test species. Fresh weight was also significantly reduced in all test species. Sunflower seedlings(Experiment 3) in the treated(with the XAD-4 resin column) were larger and healthier than those in the control (without XAD-4 resin column) because of the removal of allelochemicals. The fresh weight of sunflower seedlings was markedly inhibited by sunflower root exudates. These mean that sunflower probably is an autotoxic crop.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.191-198
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• 2011

Herbicidal effects and crop selectivity of aqueous leaf extracts of sorghum (Sorghum bicolor L.) were evaluated against several weed species for developing sustainable weed management in organic farming. Aqueous sorghum leaf extracts were highly phytotoxic to different weed species. No broadleaf weeds were germinated in the concentration of 5 fold or higher concentrated sorghum leaf extracts and 90% of seed germination was inhibited within that range in grass species. Sorghum leaf extracts strongly inhibited the growth of different weeds by pre-emergence and foliar applications in greenhouse condition. Foliar application of sorghum leaf extracts had a higher inhibitory effect than the pre-emergence application. Broadleaf weed species were more susceptible than grasses to the application of sorghum leaf extract in foliar applications than grasses. Galium spurium, Erigeron candensis, and Rumex japonicus were completely killed at the highest concentrated sorghum leaf extract both in pre-emergence and foliar application. Most broadleaf weed species were inhibited more than 80% at pre-emergence application at 50 fold concentrated sorghum leaf extract. G. spurium, E. candensis, R. japonicus, Eclipta alba, Plantago asiatica and Portulaca oleraeea were most susceptible to sorghum leaf extract in foliar application. Growth of most broad leaf weed species was suppressed by greater than 90% at 50 fold concentrated sorghum leaf extract. Most crop species were tolerant to sorghum leaf extract but shoot growth was slightly reduced by the application of 40~50 fold concentrated extracts, Sorghum leaf extract may used to control weeds in organic fanning without affecting the growth of crop.