• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.5
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• pp.442-448
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• 1992

In order to determine the critical seeding date in dry paddy field at southern plain area of Gyeongbug province, dry seeds of three different rice cultivars was sown April 25 to June 20 at 15 or 10-day intervals. The number of days from seeding to emergence decreased in late seeding date : from 32 days at April 25 to 7 days at June 10 sowing. The number of seedlings showed 121-154 plants per square meter were not much differed among the varieties and seeding dates. Culm length, panicle length and ripened grain ratio decreased in late seeding date, but number of panicles per square meter, 1,000 grain weight and spikelets number per panicle were similar among the seeding dates. The cumulative effective temperature(mean air temperature-15$^{\circ}C$) from emergence to heading was very constant having 655$\pm$9$^{\circ}C$ in Keomhobyeo, 771$\pm$9$^{\circ}C$ in Donghaebyeo and 801$\pm$3$^{\circ}C$ in Milyang 95, respectively. Grain yield of Dong Haebyeo seeded in June 20 and Milyang 95 seeded in June 10 were much lower compared with other seeding dates and increased green kernel in late seeding date of Donghaebyeo and Milyang 95.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.2
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• pp.166-172
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• 1997

This experiment was carried out to clarify the effect of the deep water irrigation on dry-seeded rice cultivation at the three different water managements-deep continuous flooding(DCF), water saving irrigation(WSI), ordinary irrigation(OI). The highest tillering numbers per $m^2$ of rice were 551, 466 and 455 in OI, WSI and DCF, respectively. The tillering number of rice plants were significantly reduced in DCF. Heading date was delayed and the total chlorophyll content in leaf after heading was higher in DCF than those in other irrigation methods. For the characteristics associated with lodging, the culm length in DCF was slightly elongated and the diameter of culm in DCF was thicker than that in WSI and OI. The breaking weight and bending moment in DCF also were higher than those in others. As the result, although the culm length in DCF was long, the lodging index was comparatively low. The panicle length in DCF was longer than in OI and WSI. The spikelet number per $m^2$ and 1,000-grain weight were the most in WSI, while panicle number, ripened grain ratio and grain weight were not significantly different. Longer panicle length and more spikelet number resulted in higher yielding capacity in DCF.

• Korean Journal of Medicinal Crop Science
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• v.7 no.4
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• pp.308-313
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• 1999

Direct seeding is a cultivation method of Korean ginseng which can cut down production cost and increase productivity. This study was conducted to obtain detailed information about this method and to aid the development of it in Korea. Major pre-crops before ginseng cultivation were rice, corn and rye, and organic matters, such as rice straw, rye straw and poultry feces were used for basal fertilization. In direct seeding of the ginseng field, seeding density was 196 to 210 seeds per $3.3m^2$ and germination ratio was 67%. Survival ratio of 4-year-old ginsengs which were products of direct seeding was 51%, and more than 100 plants per $3.3m^2$ survived. The most critical diseases in the directly seeded ginseng field were grey mold, damping off, and stem diseases including stem spot disease. Plant growth of the ginseng cultivated by the direct seeding method was not different from the ginseng cultivated by transplanting method. But the root of the ginseng cultivated by the direct seeding method took the shape of a shorter main root compared to the ginseng cultivated by the transplanting method. Root yield per $3.3m^2$ of the direct seeding ginseng field was larger compared to the field of the transplanting cultivation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.2
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• pp.124-127
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• 1998

Since weedy rice problems have emerged with the recent advent of direct seeding cultivation in Korea, the establishment of effective control strategies for weedy rice is considered to be one of the urgent issues to be solved for widely practiced direct seeding rice cultivation. A three year experiment was conducted to investigate the occurrence pattern of weedy rice in four different rice cultivation practices: high ridged dry seeding, wet drill seeding, water seeding, and machine transplanting. The highest weedy rice occurrence of 11.0% was observed in high ridged dry seeding practice followed by 9.6% in wet drill seeding, 6.4% in water seeding practice, and 0.2% in machine transplanting practice, respectively. The same trend was observed when we examine the occurrence of contamination of panicle and rice grain by weedy rice. More contamination was observed in high ridged dry seeding than any other practices. It was also found that the possible emergence depths from the soil surface was deeper in both in ridged dry seeding and wet drill seeding practice (0-5 cm from the soil surface) than those in water seeding (0-4 cm), and machine transplanting practice (0-3 cm). The highest yield reduction of 19.5% was observed in high ridged dry seeding practice followed by 13.0% in wet drill seeding, 6.3% in water seeding practice. The reduction may have occurred to the competition between weedy rice and cultivated rice, These findings suggest that among the four cultural practices examined, the machine transplanting practice is the most effective method to control and reduce the weedy rice occurrence and weedy rice seed in soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.191-196
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• 1999

In rice-barley cropping systems, efficient utilization of barley straw is essential, both to improve the soil fertility and to conserve the environment. In order to identify the effects of barley straw mulch rates in rice cultivation, a rice cultivar, 'Gancheogbyeo', was directly seeded on a no-tillage field synchronized with barley harvesting with five barley straw mulch rates, i.e., 0, 2.5, 5.0, 7.5 and 10.0 ton h $a^{-1}$ and agronomic characters of rice and soil nitrogen were determined. The increasing of barley straw mulch rates. Dominant weed species, chestnut, occurred in large amounts in no mulching or lower mulch rates than in higher mulch rates. The content of N $H_4$$_{＋}$-N in soil applied with high barley straw mulch rates was lower during the month after seeding, and then it was higher at heading date, compared with lower mulch rates or no mulch plot. As the barley straw rate increased, maximum tillering stage was delayed, and plant height was reduced. Although the lodging of rice plants was seldom observed in all plots, the breaking strength of the culm was significantly higher in the mulch rate of 10.0 ton h $a^{-1}$ . With an increase of barley straw mulch rate, the effective tillering rate and spikelet number $m^{-2}$ decreased while ripened grain ratio increased. The rice grain yield was slightly decreased with an increase of barley straw mulch rate, although significant differences were not found all barley straw mulch rates. These results suggest that there is no significant yield loss although the total barley straw production, approximately 5.0 ton h $a^{-l}$ in the present study, apply in the paddy for the following rice cultivation by no-tillage direct seeding.ect seeding.

• Korean Journal of Weed Science
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• v.14 no.4
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• pp.245-251
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• 1994

The initial growth and herbicidal responses of Scirpus planiculmis were examined under both laboratory and greenhouse condition. Initial growth of S. planiculmis at two different soils(soil A and B), was compared with the growth at normal paddy soil, and growth rates at two soils were 32% and 86% as compared to the growth rates at normal paddy soil. Two different soils were soil A(rice-uncultivable) and soil B(rice-cultivable). Transplanted(2.5 leaf stage) and direct seeded rice(Dongjinbyeo) could not grow at soil A. The growth of transplanted rice at soil B was almost same as the growth at normal paddy soil, but the growth of direct seeded rice was 50% of the growth at normal paddy soil. S. planiculmis among the perennial weeds was most tolerant to NaCl, and Cyperus serotinus, Eleocharis kuroguwai, Sagittaria pygmaea, Sagittaria trifolia, Potamogeton distinctus were followed. The intial growth rate of S. planiculmis was more rapid than C. serotinus. Cutting types and times of corm reduced 20-40% of the initial growth of S. planiculmis. During the initial growth of S. planiculmis, the growth of S. planiculmis was severly inhibited by the earlier removal of corm from seedlings, and it represents that the corm plays an important role in the initial growth of this species. Bentazone among 14 commercialized herbicides showed the best safety on direct seeded rice and the highest control effect agaist S. planiculmis.

• 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.

• Weed & Turfgrass Science
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• v.3 no.4
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• pp.323-328
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• 2014

This study was conducted to find out the effects of aerial application by unmanned helicopter (AAUH) on controlling weeds under water-seeded rice cultivation. Foliar herbicide (bentazone sodium + fenoxaprop-P-ethyl) was applied with diluted 8-times (standard concentration pest control) as AAUH. Foliar herbicide treatment with standard and two times amount were little damage, but with more than three times amount showed great damage in rice growth. Six annual and two perennial weeds were major weeds occurred in the experimental paddy field. On foliar herbicide treatment 25 days after direct seeding, AAUH showed high control values against weeds (96.3% for annual weeds and 99.8% for perennial weeds). There was no significant difference in weed control values between AAUH and conventional application. There was no spray injury against rice plants with aerial application. In the experiment for good spray timing (15, 20 and 25 days after direct seeding) 15 days showed highest weed control values with 98.5% to annual weeds and 99.8% to perennial weeds and no spray injury.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.236-242
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• 1999

To examine the seedling stand and growth as affected by early seeding dates of dry direct seeded rice in the Honam plain area of Korea, Dongjinbyeo was seeded at six seeding dates from early March to late April in rice fields of silty loam soil(Jeonbuk series) at the National Honam Agricultural Experiment Station (NHAES) for two years, 1996 and 1998. Seedling stand decreased slightly. with an early seeding date, but it produced more than the optimum seedling number except for the seeding of 25 March in 1996. Days to emergence was significantly longer, as seeding date was earlier, and days to emergence by early seeding was shortened only by 8 days because the mean air temperature was lower in 1996 than average, while in 1998, the reduction effect was nine to twenty five days because the mean air temperature was higher than average. In early seeding, various weeds occurred at the emergence date of rice and dominant weeds were Alopecurus aequailis, Ludwigia prostata and Rorippa islandica. NH$_4$$^{+}$ -N content in the soil at the 5th leaf stage and maximum tillering stage were lower, as the seeding date was earlier when nitrogen was split applied as basal and top dressed in 1996, while it was not significantly different among seeding dates when nitrogen was intensively applied as a top dressing in 1998. Tiller number at the maximum tillering stage and panicle number/m$^2$ were more, as seeding date was earlier in 1996, while it was not different in 1998. Filled grain rate and 1,000 grain weight was not different among the seeding dates. Milled rice yield was significantly decreased in the seeding before the middle of March, but in the seeding after late March, it was not varied when compared with the normal seeding date in 1996, while in 1998, there was no difference among seeding dates. From the above results, in consideration of seedling stand, weed occurance, rice growth and milled rice yield, the critical optimum early seeding time in the southern plain area may lie in early April. But it was suggested that when soil moisture is proper for seeding practices, seeding amount is increased and nitrogen is applied after plumule emergence of rice, milled rice yield may not be reduced in the seeding of middle or late March, compared with the seeding in April.l.

• The Korean Journal of Pesticide Science
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• v.3 no.1
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• pp.1-12
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• 1999

Herbicidal activities of newly synthesized experimental compound, KSC-13906 [Erythro N-{(4,6-dimethoxy pyrimidin-2-yl)aminocarbgnyl}-2-(2-fluoro-1- hydroxy-n-propyl)benzenesulfonamide, US Patent 5,461,025], were investigated in greenhouse and field for development as a paddy herbicide. KSC-13906 exihibited excellent weeding effects and selectivity to rice under submerged paddy condition in geenhouse. At the application rate of $2.5{\sim}5$ g ai/ha treated on surface of water, KSC-13906 effectively controlled three annual weeds such as Echinochloa crus-galli var. oryzicola. Scirpus juncoides, and Monochoria vaginalis as well as five perennial weeds such as Cyperus serotinus, Sagittaria pygmaea, Eleocharis kuroguwai, Potamogeton distinctus, and S. trifolia. However, there was no effect on Aneilema keisak and Lindernia procumbens. Especially, KSC-13906 effectively controlled Echinochloa crus-galli var. oryzicola at growth stages ranging from pre-emergence to 3-leaf stage. Antagonistic interaction was found between pyrazosulfuron-ethyl and mefenacet, but not between KSC-13906 ana mefenacet. KSC-13906 had high selectivity to transplanted rice, but caused phytotoxic effect on direct-seeded rice when treated before 3-leaf stage. Herbicidal activity of KSC-13906 on the Echinochloa crus-galli var. oryzicola was 7-folds greater than that of pyrazosulfuron-ethyl in terms of relative dose ratio of the herbicides. These results suggest that KSC-13906 possesses selective herbicidal potency in rice.