• Korean Journal of Weed Science
• /
• v.15 no.4
• /
• pp.305-312
• /
• 1995

Weed communities in the dry-direct seeded rice(Oryza sativa L.), soybean(Glycine max(L.) Merr.), and dry-direct seeded rice-soybean rotation system from the transplanted rice field were investigated in order to identify a change in weed species by paddy-upland rotation. Echinochloa species was the most dominant species in the dry-direct seeded rice and their great increase was observed in the continued practices of dry-direct seeded rice. Echinochloa spp., Chenopodium ficifolium, and Digitaria spp. were identified as the major weeds in soybean cultivation in paddy field. Practice of soybean rotation in the dry-seeded rice reduced weed occurrence, particularly at the soybean after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr soybean compared to the continued cultures of rice or soybean. In addition, cultivation of dry-direct seeded rice or soybean culture in the paddy rice field seemed to be helpful for suppression of perennial weeds(Eleocharis kuroguwai, Cyperus serotinus, Scirpus juncoides) and aquatic weeds(Monochoria vaginalis, Sagittaria spp. Potamogeton distinctus).

• Korean Journal of Weed Science
• /
• v.12 no.3
• /
• pp.230-260
• /
• 1992

The paper was reviewed the research results on weed dynamics and effective control methods in direct-seeded rice crop. Direct seeding method resulted in drastic increment of weed growth compared to transplanting method and also changed in troublesome weed flora. Two to three fold more weeds were harvested at the direct seeded rice and weed flora of dominant species shifted toward $C_4$type grass weeds. Some of the important troublesome weeds in direct seeded rice were Echinochloa crus-galle, Oryza saliva ssp spontanea, Leptochloa chinensis. Setaria viridus. Digitaria adsendens, Sesbania exaltata, Aeschynomene indica, Algae, etc. Yield loss due to weed competiton was about 40-60% for water-seeded and about 70-100% for dry-seeded rice while these for transplanted rice were about 25-35% for mechanical transplanting and about 10-20% for manual transplanting, respectively. Integrated weed management concept was neede to approach weed control effectively. Several cultural technologies were very effective to suppress the weed growth. These were tillage operation, water management, seeding date and seeding rate. Crop residues of barley, rice, wheat, oat and italian ryegrass were also effectivly suppressed the paddy weeds particularly to Potamogeton distiuctus, a perennial broadleaf weed. A pathogen of Epicoccosorus nematosporus identified from Eleocharis kuroguwai was an excellent potential bioagent to control the most troublesome perennial sedge weed of E. Kuroguwai without arising any detrimental effect. The herbicidal efficacy of this pathogen was as high as bentazon herbicide. Plant growth regulator of paclobutrazol (pp-333) was another possible alternative to reduce the herbicide use. In current, herbicide exhibited the most conspicuous results to control weeds in direct-seeded rice even though the application technologies were not fully established. Recommendations for herbicide application were suggested for in both water-and dry-seeded rice in USA, Japan and Korea, respectively. To make better and comprehensive recommendations further studies on weed ecology and herbicide development were emphasized.

• Korean journal of applied entomology
• /
• v.36 no.2
• /
• pp.141-144
• /
• 1997

Studies were conducted to investigate the incidense of insect pests in transplanted and direct seeded paddy fields in southern region of Korea. Population dencities of the rice green leafhopper (RGLH: Nephotettix cincticeps Uhler) and rice leaffolder (RLF: Cnaphalocroch medinalh Guenee) were higher in machine transplanted than in direct seeded, but the brown planthopper (BPH: Nilaparvata lugens Stal) and smaller brown planthopper (SBPH: Laodelphax striatellus Fallen) were abundant in direct seeded. However, no significant difference was found between machine transplanted and direct seeded fields in the incidense of rice stem borer (RSB: Chilo suppressalis Walker), whiteback planthopper (WBPH: Sogatella furcifera Horvath), and rice stem magot (RSM: C'hlorops oryzae Matsumura). Occurrence of rice key pests were affected more by transplanting time than other cultural practices. Later transplanting induced higher populations of BPH, WBPH, SBPH, RGLH. However, RSB and RLF caused higher damage in earlier transplanted paddy field.

• Korean Journal of Weed Science
• /
• v.18 no.1
• /
• pp.12-19
• /
• 1998

The pattern of rice cultivation in Korea is changing from hand transplanting and machine transplanting into direct-seeding for low input and cost-down practices. However, there are still some obstacles to establish the direct-seeding cultural practices because of poor seedling stand, lodging, and weed infestation. In particular, there were much more and wide weed occurrence in direct-seeding rice as compared with the transplanted rice. Weed occurrence in terms of dry weight of weeds was highest in dry direct-seeded rice followed by sowing an puddled soil, sowing on submerged soil in order as compared with transplanting with infant rice seedling. Echinochloa crux-galli was a common dominant weed with 35~44% distribution in any direct-seeding methods. The dominant weed species were E. crux-galli, Cyperus difformis, C. serotinus, and Ludwigia prostrata in dry-seeded rice. The dominant weed species in water-seeded rice were E. crus-galli, Eleocharis kuroguwai, Scirpus juncoides, and Monochoria vaginalis. Yield loss of rice due to weeds at weedy condition was 96% in dry direct-seeded rice. In water-seeded rice, yield loss was 61%, whereas yield loss was 40% in machine transplanting with infant rice seedling.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.3
• /
• pp.352-356
• /
• 1997

In order to trace the survival route of weedy rice in Korean farmer's field, occurrence rate and position of weedy rice, number of weedy rice plants per $m^2$, in transplanted and direct seeded field were investigated. The highest occurrence rate of weedy rice in transplanted field was 5.5％. Number of weedy rice plants in direct seeded field was higher than that in transplanted field. In transplanted field, most of the weedy rice were grown within hills of cultivated rice and only a few was grown between hills of the cultivated rice, however in direct seeded field the number of weedy rice occurred between hills or rows of cultivated rice was higher than that occurred within hills or rows. Weedy rice occurrence rate in the field of .non-recommended rice variety was higher than that in the field of recommended variety. The main survival route of weedy rice in transplanted field was supposed to be mixture of weedy rice seeds with cultivated rice, and that in direct seeded field to be natural survival.

• Korean Journal of Veterinary Service
• /
• v.18 no.3
• /
• pp.1-12
• /
• 1995

To investigate effect of seeding on post-thaw motility and viability of canine spermatozoa, the semen from male dogs which had been proved to be fertile in the past were frozen and seeded during freezing process. Post-thaw motility and viability of canine sperm which were frozen and seeded were investigated according to different seeding temperatures of $-5^{\circ}C$, $-10^{\circ}C$, or $-l5^{\circ}C$ and also according to different concentration of glycerol of 2%, 5% and 10%. In addition, post-thaw motility of canine sperm frozen by direct freezing in a deep freezer or programmed freezing in a programmed cell freezer was investigated. Post-thaw motility of canine sperm was compared according to different seeding temperatures : The sperm seeded at $-5^{\circ}C$ showed considerably higher post-thaw motility than that of non-seeding, and that seeded at $-10^{\circ}C$, or $-l5^{\circ}C$, respectively, in 2% and 5% glycerol groups on both 2 and 7day after freezing(p<0.05). In 10% concentration of glycerol, the sperm seeded at each seeding temperature showed considerably higher post-thaw motility than that of non-seeding group on day 7 after freezing(p<0.01). Post-thaw viability of canine sperm was compared according to different seeding temperatures : The sperm seeded at $-5^{\circ}$ showed significantly higher post-thaw motility than that of non-seeding, and that seeded at $-10^{\circ}C$, or $-l5^{\circ}C$, in 5% and 10% glycerol groups on day 7 after freezing(p< 0.05). In comparison of post-thaw motility of canine sperm seeded according to different concentration of glycerol, 5% glycerol group and 10% glycerol group showed considerably higher post-thaw motility than 2% glycerol group without difference between those two groups in all seeding temperatures($-5^{\circ}C$, $-10^{\circ}C$ and $-l5^{\circ}C$) on day 2 and 7 after freezing(p<0.01). In comparison of post-thaw viability of canine sperm seeded according to different concentration of glycerol, 5% glycerol group and 10% glycerol group showed the same considerably higher post-thaw viability than 2% glycerol group on each thawing day(p<0.01). The canine sperm frozen and seeded by programmed freezing method showed considerably higher post-thaw motility than that frozen by direct freezing method in all different seeding temperatures($-5^{\circ}C$, $-10^{\circ}C$ and $-l5^{\circ}$). These results indicated that the higher post-thaw motility and viability was obtained in the spermatozoa seeded than that of non-seeding, that among different seeding temperatures of $-5^{\circ}C$, $-10^{\circ}C$ and $-l5^{\circ}C$, the sperm seeded at $-5^{\circ}C$ showed higher post-thaw motility and viability than the other temperatures, also among different concentrations fof glycerol of 2%, 5% and 10%, the sperm frozen and seeded in 5% and 10% concentration of glycerol showed higher post-thaw motility and viability than that in 2% of glycerol, and that the sperm frozen and seeded by programmed freezing method showed higher motility than that by direct freezing method.

• Korean Journal of Weed Science
• /
• v.13 no.2
• /
• pp.159-163
• /
• 1993

This research was conducted at the Crop Experiment Station to determine the changes of weed flora under direct seeded rice cultivation in dry paddy field from 1989 to 1992 and to establish an effective weed control strategy in direct seeded rice cultivation. With the continuous rice growing under direct seeded rice cultivation in dry paddy field, there were more occurrence in grasses and annual weeds while broadleaf and perennial weeds were diminished. The predominant weeds were aquatic weeds such as Eleocharis kuroguwai, Echinochloa crusgalli, and Monochoria vaginalis in machine transplanted rice paddy field while there were predominant of semi aquatic weed species such as E. crusgalli, Digitaria sanguinalis, Bidens tripartita, Aeschynomene indica, and Arthraxon hispidus in continuous direct seeded rice cultivation in dry paddy condition. Based on the vegetative analysis of weeds in terms of simpson index and community dominance, there was more distribution of weed species in direct seeded rice cultivation on dry paddy condition while only distributed with 1-2 weed species in machine transplanted rice paddy field. In similarity coefficient, there was a gradual increase up to 67% of weeds with the continuous direct seeded rice cultivation in dry paddy condition for 4 years starting from 41% of similarity coefficient.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.52 no.3
• /
• pp.249-258
• /
• 2007

Experiments were conducted with aims to (1) estimate the biomass yield potential, (2) characterize the biomass and digestible dry matter production, and (3) reveal the characteristic seedling establishment of a whole crop rice variety, Nogyangbyeo, in dry- and wet-seeded rice. Maximum aboveground total biomass of Nogyangbyeo was 18 t $ha^{-1}$ in dry-seeded rice and 20 t $ha^{-1}$ in wet-seeded rice. Biomass yield potential of Nogyangbyeo was lower than that of Dasanbyeo. Comparatively, Nogyangbyeo was straw-dependent and Dasanbyeo was grain-dependent for biomass accumulation. Percentage of digestible dry matter (DDM) was higher in panicles than straw. Digestible dry matter yield was determined mainly by biomass yield rather than DDM percentage. Number of seedling establishment in Nogyangbyeo was $73m^{-2}$ in dry-seeded rice and $109m^{-2}$ in wet-seeded rice. Poor seedling establishment of dry-seeded Nogyangbyeo in the field condition was the result of low seed germination under low temperature and poor seedling emergence by deep sowing. Low seedling emergence rate of Nogyangbyeo was attributed mainly to slow elongation growth by slow leaf development and partly to mesocotyl and 1st internode lengths, not to genetically defined leaf length. The slow elongation growth of Nogyangbyeo was the same even in the high daily mean temperature of $24^{\circ}C$. Results suggest DDM yield in rice can be improved simply by increasing biomass and whole crop rice varieties should be adaptable to direct-seeding.

• Korean Journal of Weed Science
• /
• v.15 no.4
• /
• pp.278-288
• /
• 1995

Weed species occurred in dry- and water-seeded rice were 14 (2 grasses, 8 broadleaves, and 4 sedges) and 12 species (1 grasses, 7 broadleaves, and 4 sedges), respectively. Dominant weed species in dry-seeded rice were Lindernia procumbens, Cyperus difformis, Cardamine flexuosa, and Cyperus serotinus in discending order. The species in water-seeded rice were Cyperus difformis, Scirpus juncoides, and Lindernia procumbens. The number of weed species emerged in direct-seeded rice was determined at about 45 days after seeding, and dry weights of weeds were increased up to 75~90 days after seeding. Timing for great increase of plant height varied depending upon weed species. Regardless of weed number emerged, the most dominant weeds until late stage of growth were Cyperus difformis, Bidens frondosa, Digitaria ciliaris and Echinochloa crus-galli in dry- seeded rice, and Cyperus difformis, Echinochloa eras-galli and Scirpus juncoides in water-seeded rice.

• Korean Journal of Weed Science
• /
• v.32 no.1
• /
• pp.57-69
• /
• 2012

This study was conducted to find the effective management of main weeds including herbicide-resistant Echinochloa oryzicola, Scirpus juncoides and Monochoria vaginalis in direct seeded rice on puddled paddy surface. The dominant dominances in direct seeded rice on puddled paddy surface were increased for three years between 2009-2011. In weed distribution in 2011, the occurrence density of S. juncoides decreased greatly, but it of E. oryzicola increased especially as compared with it of 2009. Benzobicyclon, mesotrione and pyrimisulfan were effective to sulfonylurea(SU)-resistant S. juncoides and M. vaginalis at 5 and 12 days after seeding, however, the efficacy of bromobutide to sulfonylurea-resistant M. vaginalis was decreased slightly at 12 days after seeding. And carfentrazon and pyrazolate were ineffective to S. juncoides. In direct seeded rice on puddled paddy surface which ACCase and ALS inhibitor-resistant E. oryzicola was not occurred, benzobicyclon+penoxsulam+pyrazosulfuron-ethyl ET, bromobutide+imazosulfuron+metamifop GR, and flucetosulfuron+mesotrione+pretilachlor GR showed the control effect over 94% to main weeds included sulfonylurea-resistant S. juncoides and M. vaginalis. The E. oryzicola dominating in direct seeded rice on puddled paddy surface were not any affected to the survival by treatment with recommended doses of cyhalofop-butyl and penoxsulam tested. The ACCase and ALS inhibitor-resistant E. oryzicola was effectively controlled by mefenacet and fentrazamide up to the 2nd leaf stage. In direct seeded rice on puddled paddy surface domiating coincidentally by herbicide-resistant E. oryzicola, S. juncoides and M. vaginalis, "one-shot herbicide" included with mefenacet, fentrazamide, penoxsulam and metamifop could't be used because of low control effect or rice injury. The sequential treatment of benzobicyclon+thiobencarb SE and bensulfuron+mefenacet+thiobencarb GR controlled effectively the herbicide-resistant E. oryzicola, S. juncoides and M. vaginalis in direct seeded rice on puddled paddy surface. The days required by the 3rd leaf stage of herbicide-resistant E. oryzicola, S. juncoides and M. vaginalis in direct seeded rice on puddled paddy surface seeded in May 20 shortened by 4 days as compared with it of June 10.