• Korean Journal of Weed Science
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• v.9 no.1
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• pp.46-55
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• 1989

Stomatal variation was observed at the Yeongnam Crop Experiment Station in 1988 using 42 rice cultivars and 30 weed species. The shape, density or size of stomata was varied depending on the species. Two general trends, however, were found that more number of stomata was found at lower leaf epidermis than upper leaf epidermis and stomata number was negatively correlated with stomata size. Aneilema japonica and Portulaca oleracea had the least number of stomata having 17-20 stomata per $m^2$ for upper leaf epidermis and 17-54 stomata for lower leaf epidermis while Polygonum conspicuum had the greatest number of stomata (449 for upper leaf epidermis and 511 for lower leaf epidermis). Soybean, Aeschynomene indica, Ludwigia prostrata and Lactuca indica had the smallest in stomata size while the biggest stomata was found at P. oleracea and A. Japonica that had the least number of stomata. Cyperus species such as C. difformis, C. iria and C. serotinus had no stomata at upper leaf epidermis. The stomata were distributed only at lower leaf epidermis for these species. Potamogeton distinctus, on the other hand, had stomata almost at upper leaf epidermis and thus, hardly found the stomata at lower leaf epidermis. Among rice cultivars, Tongil-type had the greatest number of stomata followed by Indica-type and Japonica-type, in order. Cultivars released after 1960 had more stomata than cultivars released before 1960 for Japonica-type cultivars while stomata size had reversed trend. Jinheung had the least number of stomata (${\fallingdotseq}$ 150 per $mm^2$) while Yushin had the greatest number of stomata (350 for upper and 449 for lower leaf epidermis, respectively) among rice cultivars. Other cultivars having more than 350 stomata per $mm^2$ were Samgangbyeo, Milyang 23, Woonbongbyeo, etc.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.1
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• pp.77-86
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• 1980

Asking to change the cropping patterns to save the labor and capitals in paddy rice cultivation, the study was intended to know the weed problems under the various possible cultural systems; namely, direct seeding (in broadcast and row), machine transplanting and hand transplanting. Under the conditions as weedy check plots, paddy yields were significantly variated among cropping systems, and the functions of panicle No. and spikelet No. to the yield were neglected, among others. However, the yield and yield components were narrowed among cropping systems, and the function of spikelets number per area was comparatively improved to the others.

• The Korean Journal of Pesticide Science
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• v.6 no.4
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• pp.320-323
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• 2002

New and fast degradable sulfonylurea derivaties possessing N-methylureido group were synthesized and their herbicidal effects were tested under the upland in greenhouse. N-methylureido benzenesulfonylureas showed better herbicidal activity against grass weeds than broad leaf weeds under post emergence.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.166-173
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• 1983

To investigate the varietal differences of weed competitive functions under the three different seasons of transplanting, rice cultivars Milyang 23 and Sadominori were used with seven weeding methods, namely, weedy check, weed-free, once weeding at 3, 6, 9, 12 weeks after transplanting, and two times weeding at 3 and 9 weeks after transplanting, respectively. As a result, weeding stages and times for the proper weeding efficacies and reasonable rice productivities by respective weed group and total weed flora were estimated. Also, the constructive characteristics for yield formations under the different competitive conditions as affected by various cropping patterns were discussed.

• The Korean Journal of Pesticide Science
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• v.7 no.4
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• pp.239-247
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• 2003

This experiment was carried out to study the resistant mechanism of sulfonylurea(SU) herbicides to Monochoria korsakowii occurring in the rice fields of Korea. The activity of acetolactate synthase(ALS), absorption and translocation of $[^{14C}]$bensulfuron-methyl, and DNA sequence of ALS genes were studied. The apparent SU resiatance to Monochoria korsakowii was confirmed in greenhouse testes. Fresh weight accumulation$(GR_{50})$ in the resistant biotype was about 5- to 64-fold higher in the presence of six SU herbicides compared to the susceptible biotype. The ALS activity isolated from the resistant biotype to herbicides tested was less sensitive than that of susceptible biotype. The concentration of herbicide required for 50% inhibition of ALS activity$(I_{50})$ was 14- to 76-fold higher as compared to the susceptible biotype. No differences were observed in the rates of $[^{14C}]$bensulfuron uptake and translocation. However, the DNA sequence from the resistant biotype differed from that of the susceptible biotype by single nucleotide substitution at three amino acid each in the middle region excluding the ends of ALS genes. We found three point mutations causing substitution of serine for threonine at amino acid 168, arginine for histidine at amino acid 189, and a aspartic acid for phenylalanine at amino acid 247, respectively, in the resistant biotype.

• Weed & Turfgrass Science
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• v.6 no.3
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• pp.235-248
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• 2017

This study was initiated to investigate seed germinating vigor, germination speed, and establishment characteristics of Festuca species under natural conditions ($5-25^{\circ}C$). Germination rate was 62.0% in CRF 'Audubon' to 97.0% in TF 'Olympic Gold'. It was greater with TF over fine-type fescues, being TF>SF>CF, HF>CRF. The germination speed, measured as days to seed germination of 50% through 80%, was fastest with TF, medium to high with CF, medium with HF and SF, and slowest with CRF. However, it was approximately 4 days slower under natural conditions, as compared with that under alternative conditions ($15-25^{\circ}C$). Germination peak time was much faster with TF. It ranged from 0.73 to 1.84 days with TF, being 1.45 days in average. But it varied with 2.16 to 11.75 days among fine-type species. The peak time was longer in order of SFCF>SF>HF>CRF.

• Korean Journal of Weed Science
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• v.12 no.1
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• pp.39-45
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• 1992

This experiment was conducted to evaluate the effect of gibberellin biosynthesis retardants as used by rice lodging inhibitors on the gibberellin antagonism, auxin interation, ethylene evolution and growth of second crops. Results obtained can be summarized as follows. Inabenfide, paclobutrazol and uniconazole markedly inhibited the epicotyl elongation of mung bean. Inhibiting effect of epicotyl by these chemicals was markedly stimulated by gibberellic acid, thus showing clear antagonism between these chemicals and gibberellic acid. Significantly large number of roots were formed in the mung bean cuttings which were rooted in the paclobutrazol and uniconazol of 1 ppm. The higher the concentration, the more the number of roots forms. It was guessed that these effect was closely related with auxin. Ethylene evolution was a little stimulated in the leaf of rice under the treatment of inabenfide, paclobutrazol and uniconazole at earlier stage(5 DAT), however it was suppressed at later stage(10, 30 DAT) at higher concentration. The effect of gibberllin biosynthesis inhibitors to second crops retarded tomato plants without influencing the height of barley. The treatment of paclobutrazol and uniconazol which is triazole-type more severely inhibited than that of inabenfide which is isonicotinanilide-type. The more the concentration, the less the height of tomato plants.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.421-428
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• 2010

A foliage contact herbicidal substance was separated from ethyl ether fraction in n-hexane extract of Saussurea lappa roots and identified as dehydrocostus lactone [(3aS,6aR,9aR,9bS)-3,6,9-trimethylidene-3a,4,5,6a,7,8,9a,9b-octahydroazuleno[5,4-d]furan-2-one](DHCL). When DHCL at 4,000 ppm was foliage-applied to two grasses and two broadleaf plants, greater than 85% necrotic injury was obtained from large crabgrass, maize and soybean, whereas only about 40% necrotic injury appeared in black nightshade, indicating that DHCL has no gross morphological selectivity, but shows difference in contact response among the plant species tested. Conductivity in incubation medium of the leaf disks treated with DHCL increased as the incubation time continued. Relatively low contact injury in black nightshade as compared with the other three plant species tested was attributed to decrease in absorption of DHCL due to relatively high amount of cuticle. DHCL did not require light in the herbicidal action and there were no inhibitory effects on seed germination and cell elongation. Acetyl-CoA carboxylase activity was inhibited by 30% and 58% at $100\;{\mu}M$ and $1000\;{\mu}M$ DHCL, respectively. These results suggested that the herbicidal action of DHCL was related with inhibition of fatty acid synthesis which in turn caused to weaken cell membrane integrity.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.143-152
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• 2010

Herbicidal characterisitcs of natural product chrysophanic acid were investigated in a greenhouse condition. At early- and middle-stage post-emergence treatments, several grasses and broadleaf weeds appeared to be very susceptible to chrysophanic acid. However, any significant herbicidal activity treated by pre-emergence did not occur at concentration ranges from 31.3 to 1,000 ug $mL^{-1}$. Herbicidal activity of chrysophanic acid estimated by visual injury for large crabgrass was much higher when applied at 7 to 14 days after seeding than at 21 and 28 days after seeding. By post-emergence treatment, chrysophanic acid caused very considerable phytotoxicity on several grasses and broadleaf crops. In herbicidal interaction experiments determined by Colby's method, the effect of chrysophanic acid and caryophyllene oxide tank-mixture showed very high synergistic activity. Although chrysophanic acid did not give any pre-emergence effect, herbicidal spectrum tended to be very wide and strong when treated by post-emergence. These results suggest that chrysophanic acid possesses a possible potential to develop as a natural herbicide.

• Journal of Animal Science and Technology
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• v.45 no.5
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• pp.865-874
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• 2003

Red sorrel, as one of exotic weeds in Korea, was introduced along with imported cereals for concentrate feed or within the seed for forage production. The plant was dominated in grassland and reduced the quality of forage. In particular, this weed cause severe problem in alpine grassland. This study was carried out to investigate the effect and response of red sorrel and forage crops by foliar and soil applied herbicide application. Mecoprop(MCPP) and pendimethaline were selected by pre-field experiment trials and applied to control the red sorrel in grassland. Herbicidal activity of MCPP was 77.2% at 500$m\ell$/10a level and 82.8% at 750$m\ell$/10a level. However, seeds of red sorrel from bare land formed after foliar applied herbicide treatment were germinated and covered bare land. Pendimethalin was not reduced the rhizome growth grown from red sorrel root but retarded seedling growth of germinated red sorrel. The herbicidal activity of pendimethalin to the red sorrel seedling was 83.0%. 2 times application of MCPP at the rate of 750$m\ell$/10a was effective to control of red sorrel regrown from root and herbicidal activity was 93.2%. MCPP and pendimethaline treatment was not reduced growth of grass and have no herbicidal injury to forage crop seedling. Amount of MCPP and pendimethalin remained in grass plant was decreased from 20 days after herbicide treatment and could not be problem in livestock feeding.