• Korean Journal of Weed Science
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• v.3 no.2
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• pp.129-136
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• 1983

To study ecological characteristics of Sagitiaria pygmaea and Sagittaria trifolia occurring in Korea their propagules were collected from 3 locations (Sagittaria pygmaea: Chuncheon, Suweon, Milyang; Sagittaria trifolia: Suweon, Iri, Jeonju) in 1981, cultured and replanted 4 times (May 20, June 5, June 20, July 5) in 1982. Sagitraria pygmaea from Suweon flowered earlier than those from Chuncheon and Milyang in the plants planted on May 20, but this was reversed in another planting dates. Three storied inflorescence was observed newly in Sagittaria pygmaea. Sagittaria pygmaea from Iri and Jeonju had more number of tillers, but less number of tubers per tiller than those from Suweon. Sagittaria rrifolia from Chuncheon flowered earlier than those from Suweon and Milyang. Sagirtaria trifolia from Milyang was narrower in the upper leaf width and less in the number of tubers per plant than those from Chuncheon and Suweon. Each of local collections may be regarded as different ecotype based on the above differences.

• Korean Journal of Weed Science
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• v.9 no.2
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• pp.97-102
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• 1989

1. IAA showed no significant growth of root primordia and then lateral root emerged at 2 days after IAA treatment. BA treatment, however, strongly inhibited the formation of root primordia and a few lateral roots, if any, emerged about 5 days after treatment. 2. Treatment of BA and Indol-B on the water retaining ability sampled 1, 3, 5 days after chemical treatment was apparent on the soybean sprouts sampled 5 days after treatment while the difference among the treatments was negligible when sampled 1 and 3 days after treatment. 3. BA stimulated ABA content in the hypocotyl while inhibited ABA content in the root of soybean sprouts. ABA may relate with water retaining ability. 4. Soaking the soybean seeds to several seed disinfectant chemical solution had no effect on the growth and elongation of soybean sprouts. 5. It can be recommended that container of soybean sprouts should be shut tight during growing period except irrigation because the ethylene accumulation in the container may stimulate hypocotyl swelling and inhibit length of soybean sprouts.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.143-150
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• 1983

Red rice (local name "Sore") as a weed has been a serious threat to rice production in direct-seeded rice culture in Ganghwagun, Gyeonggi province. In the Ganghwagun 508 ha out of 1,420 ha in the Samsanmyeon area is infested with red rice. The average lowland rice yield is about 4,300 kg/ha in the Ganghwagun, but the average upland rice yield is about 2,000 kg/ha in infested area. This study was carried out in order to clarify the ecological characteristics of red rice and factors affecting the competitive ability of five red rice varieties, collected from Samsanmyeon in 1981, with rice cultivar. Five varieties-Monggeunsare, Salsare, Ginkaragsare, Galsaegsalsare, Galsaegkaragsare-showed the same morphological characteristics of cultivated Japonica type, Chuncheongbyeo, but red rice tillers more profusely, is taller and lodges more easily than Chucheongbyeo. It shatters easily about 10-15 days after heading date, and at this time the hull is discolored in yellow or dark brown. There are many types of red rice with short or long owns on the spikelet, occasionally with or without own on the spikelet in the same hill, and the grains are short or long. In red reice leaf blast occurs more severely than in cultivated Indica/Japonica type, Teabaegbyeo, particulary serious in Monggeunsare. When red rice invaded in direct-seeded rice, number of panicles of rice became reduced more than other yield components.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.156-165
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• 1983

This experiment was conducted to find out the effect of competitive duration and density of Cyperus serotinus Rottb. on rice growth and yield. In plant height of both rice and flatsedge, the compacter density of flatsedge, the higher was plant height. Rice in the 50 days competition with flatsedge had shorter culm than in other competition plots at all density. The panicle number was affected during the tillering stage. The spikelet number per panicle was influenced from 25 days to 50 days after transplanting. Grain maturity ratio and 1,000 grain-weight didn't decrease under competition before 50 days after transplanting. The competition during the tillering stage to the young panicle initiation stage decreased significantly rice yield. The rice competed with low density of flat sedge showed small decrement of yield and its components. The period reaching to maximum stem number of flatsedge become shorter as flatsedge density increased. Number of flatsedge tubers competed with rice produced was 40.1, 16.8 and 11.4 times as much in 1: 1, 1:3 and 1:5 density ratio of rice to flatsedge, respectively. Flatsedge dry matter weight and rough rice yield had the relationship of Y = 601. 95-$0.67x^{**}$.

• 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.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.174-189
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• 1983

Experiments were conducted to evaluate the herbicidal characteristics of pyrazolate [4-(2,4-dichloro benzoyl)-1,3-dimethylpyrazol-5-yl-p-toluene-sulphonate] in greenhouse and lowland rice field. Pyrazolate controlled effectively most of annual weeds and such perennial weeds as Sagittaria pygmaea MIQ., Potamogeton distinctus A. BENN, Sagittaria trifolia L., Cyperus serotinus ROTTB, and Scirpus hotarui OHWI., whereas Eleocharis kuroguwai OHWI. was tolerent to pyrazolate. Although pyrazolate was applied at 2 to 10 days after transplanting, there was no difference in weed control The weeding effect was not influenced by percolation, depth of water and soil type. No difference in crop injury of rice was found with various levels of seedling age, transplanting depth, percolation, depth of water, soil type and time of application. When combined with butachlor, the mixture gave the same effect on rice phytotoxicity and weed control as pyrazolate alone did. Pyrazolate moved 1 to 2cm downward in lowland soil regardless of soil type and percolation. The herbicidal activity of pyrazolate persisted in soil for 60 to 90 days, depending on soil type, percolation and presence of soil microorganism.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.190-198
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• 1983

To examine the possibility of enhancing activity of foliar applied herbicides by spray methods and additives, field experiments were conducted to evaluate the effects of surfactant, spray volume, and additions of ammonium sulfate or potassium chloride to glyphosate on toxicity to Digitaria sanguinalis or Artemisia princeps. Glyphosate toxicity increased as spray volume was decreased from 120 1/10a to 40 and 80 1/10a. Additions of surfactant in the spray solution increased toxicity of glyphosate to D. sanguinalis and usually more pronounced effect was obtained at glyphosate 30.5g a.i./10a. Additions of 1 and 5% (w/v) ammonium sulfate to glyphosate increased toxicity to A. princeps at glyphosate 30.5 and 61.5g a.i./10a. 10% ammonium slufate, however, had no effect or were antagonistic. Additions of potassium chloride at 1,2 and 3% (w/v) were also very effective to increase herbicidal activity to A. princeps at glyphosate at 30.5 and 61.0g a.i/10a. These results suggest that the practices for enhancement of herbicidal activity by improvement of spray method and additions of ammonium sulfate or potassium chloride to glyphosate can be employed to use lower herbicide levels while giving the same degree of weed control in orchards and non-crop lands.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.208-222
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• 1983

To control ideally the weeds in orchards and systematize the utility of herbicides, the mixing effect of oxyfluorfen and paraquat was evaluated. Combinations of oxyfluorfen with paraquat were increased the control efficacies at any treatment without giving damage to fruit trees and appeared a synergism. The control effects were reduced from 80-90% to 40-60% as the time advanced. However, the relative synergistic index was higher at 60 days after treatment in preemergence treatment and at 90 days after treatment in early and late postemergence treatment, respectively. Also the index was relatively higher at lower dosage of both herbicides.

• 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.3 no.2
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• pp.223-245
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• 1983

Nationwide weed survey of paddy rice field conducted in 1981 and 1971 was compared and determined major dominant weed community types distributed by province. Based on the similarity coefficients between 1971 and 1981 the floristic composition based on the degree of dominance was greatly dissimilar while kind of weed flora were not much differed. Degree of dominance were concentrated to perennial weeds in 1981 while these were at animal weeds in 1971. The moat important 10 weed species and their dominance in 1981 were Monochoria vaginalis Presl.(22.2%), Sagittaria pygmaea Miquel(17.5%), S. trifolia L.(9.0%), Poramogeton distinctus Benn.(9.0%), Cyperus serotinus Rottb.(8.5%), Rotala indica Koehne(6.0%), Aneilema japonica Kunth(4.4%), Lindernia procumbens Philcox(3.9%), Eleocharis kuroguwai Ohwi(3.4%) and Ludwigia proarrara Roxb(3.0%), respectively while these for 1971 were R. indica(34.5%), Eleocharia acicularis Roem, et Schult (11.9%), M. vaginalis(11.1%), Cyperua difformis L.(8.7%), Echinochloa crus-galli Beauv.(6.9%), L. procumbens(3.3%), P. distinctus(3.1%), A. Japonica (2.4%), E. kuroguwai(1.8%) and P. hydropiper(1.8%), respectively. Weed occurrence was also closely related with soil type, cropping pattern and cultural practices. Particularly, the occurrence of P. distincrus was negatively correlated with the degree of land utilization. Weed community types dafined by two-dimensional ordination analysis were 11 for Jeonnam province, 9 for Gyeoaggi, Gangweon, Chungbuk and Gyeongnam provinces, 8 for Jeonbuk and Gyeongbuk provinces, 7 for Chungnam province and 4 for Jeju province, respectively.