• Korean Journal of Weed Science
• /
• v.18 no.4
• /
• pp.341-347
• /
• 1998

This study was carried out to investigate the effect of U-Granule formulation of molinate(S-ethylhexaphdro-1H-azepine-1-carbothioate) mixtures in green house and paddy field, Five minutes were taken for U-Granule to spread out 7m in irrigated water of direct seeded on flooded paddy surface. The concentration of active ingredient of molinate in molinate U-Granule application was similar to molinate+simetryn U-Granule application. But weeding effect of molinate+simetryn U-Granule on Echinochlor crus-galli was 23% higher Than single application of molinate at 7m from application point. Bioefficacy of molinate+simetryn+imazosulfuron U-Granule on control of Echinochloa crus-galli was higher than that of molinzte+imazosulfuton U-Granule, but those effect on Eleochairs kuroguwai was not significantly different. Only slight rice phytotoxicity was observed at 5m and 2m from application point of U-Granule molinate+simetryn+imazosulfuron and molinate+imazosulfuron, respectively. So it is concluded that there is little phytotoxicity problem in practical application of U-Granule of molinate mixtures.

• Korean Journal of Weed Science
• /
• v.12 no.4
• /
• pp.335-351
• /
• 1992

The identification of green algae which were collected from paddy rice fields of the whole nation was conducted in 1991, and also the reproduction processes of three important green algae were investigated. The green algae identified were 46 species in 16 families including 4 species in the Volvocaceae, 4 species in the Palmellaceae, 3 species in the Ulotrichaceae, 3 species in the Oocystaceae and 6 species in the Scenedesmaceae. It was recognized that the algae which have caused a large injury to the flooded direct-seeded rice in Seosan reclaimed saline land was the genus Cladophora. The green water blooms on paddy water were induced mostly by the concentrated populations of suspended green algae such as the genera, Chlamydomonas and Stichococcus. A rapid propagation of Hydrodictyon was resulted from the asexual reproduction forming autocolony in each mother cell. The sexual and asexual reproduction processes of Oedogonium and the sexual reproduction process of Spirogyra were observed.

• Weed & Turfgrass Science
• /
• v.7 no.2
• /
• pp.166-169
• /
• 2018

Repeated use of ACCase inhibiting herbicides for a long time has resulted in increases of resistant Echinochloa oryzicola populations in paddy fields in middle west area of Korea. This study aims to investigate current status of herbicide resistant E. oryzicola in Gyeongsangnam-do, in which there is less information about herbicide resistance. For resistance frequency and dose-response study, seeds from 100 individual plants of E. oryzicola in Gyeongsangnam-do were collected and tested with cyhalofop-butyl. Seven percent of plants from Gyeongsangnam-do was resistant at a recommended rate of cyhalofop-butyl. $GR_{50}$ values (herbicide rates required to reduce plant growth 50%) for one representative resistant populations and five susceptible populations were $738g\;a.i.\;ha^{-1}$ and 66-234 (average 147)$g\;a.i.\;ha^{-1}$, respectively, indicating average 5 times difference in resistance. Although lower rate of frequency of herbicide resistance in Gyeongsangnam-do than in Jeollabuk-do, increases of herbicide resistance are expected in this area because of increases of direct seeded rice fields and increases of dependence on a specific herbicide. Therefore, it is necessary to monitor herbicide resistance regularly and conduct integrated herbicide resistance management in this area.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.39 no.5
• /
• pp.502-511
• /
• 1994

Investigated were the relationships between plumule elongation characteristics and seedling emergence of 98 varieties including native, improved and red rice varieties of Korea, and varieties from U.S.A., Italy, Japan, etc. under proper and excess soil moisture regimes. Under excess soil moisture condition the seedling emergence and establishment rates were much lower in most of the varieties and the seedling emergence rates were delayed substantially in all varieties employed. The seedling emergence rates were lowest in dwarf and some semi-dwarf varieties showing poor plumule elongation under proper soil moisture condition. The seedling emergence and establishment rates were significantly correlated with the length of mesocotyl, coleoptile and incomplete leaf under both soil moisture regimes, and with the lower first and second internode length under excess soil moisture condition. Average emergence duration showed significant negative correlation with the length of mesocotyl, coleoptile and incomplete leaf under both soil moisture regimes and significant positive correlations with the first and third lower internode length. Based on the standardized partial regression analysis only the variations of mesocotyl and coleoptile length contributed significantly to the varietal difference in seedling establishment rate, and so did the variations of mesocotyl and incomplete leaf length to the varietal differences in emergence speed. In conclusion varieties with greater elongation characteristics of mesocotyl, coleoptile and incomplete leaf are desirable for higher and speedy seedling establishment in dry-direct seeding.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.40 no.5
• /
• pp.562-568
• /
• 1995

Changes in rice yield and soil chemistry of dry seeded rice in double cropping of rice and barley were investigated at National Yeongnam Agricultural Experiment Station during 5 years (1990-1994). Barley straw added or removed dry seeding had safe rice seedling stand for good rice production. However, the coefficient of variation of seedling stand by year was higher than dry seeding in rice single crop. Rice seedling height was slightly reduced by barley straw incorporation. However, it recovered soon as rice growing progressed. Heading time delayed 4 days in flat seeding method but not in high-ridged seeding method which imply that. this is more safe seeding technology than flat seeding method. Comparing to rice single crop, barley straw added dry seeding increased rice yield by 2∼19%(Average of 5 years: 8%) from second year due to higher panicle and spikelet number. Contents of organic matter was 2.71% in 1990. In 1994, it decreased 2.61% for rice single crop, while increased 3.02% and 3.41% for barley straw removed or added field, respectively. Rice grain quality was not significantly different among cropping patterns.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.38 no.2
• /
• pp.174-182
• /
• 1993

Performance of 3 indica ${\times}$ japonica(Chilseungbyeo, Samgangbyeo, and Gayabyeo), 7 japonica(Yeongsanbyeo, Yeongdeugbyeo, Hwajinbyeo, Palgongbyeo, Seumjinbyeo, Tamjinbyeo, and Milyang 95), and 2 indica(Tebonnet and Lemont) rice varieties was tested at 1, 3, 5, and 7cm seeding depths in a growth chamber and field. In the growth chamber the number of days from seeding to seedling emergence increased as seeding depth increased, while percent germination and emergence and emergence / germination ratio decreased. However, in the field seedling emergence at 1em seeding depth delayed slightly compared to 3cm probably due to lack of soil moisture. The number of seedlings and maximum tillers at 1, 3, and 5cm seeding depths was similar, but it was higher compared to 7cm seeding depth. Yield and yield components were similar among the seeding depths when all the varieties averaged although 1,000-grain weight was slightly higher at 7cm deeding depth compared to others. At 1cm seeding depth the length of mesocotyl of all varieties was similar and ranged 0.1-0.2cm and that of coleptile ranged 0.8-1.1cm. As seeding depth increased up to 7cm Tebonnet which showed the highest percent emergence emerged by elongation of both mesocotyl and coleoptile, while the other varieties emerged largely by elongation of coleoptile.

• Korean Journal of Weed Science
• /
• v.18 no.1
• /
• pp.28-35
• /
• 1998

Cyhalofop/bentazon ME and pyribenzoxim EC herbicides were originally developed as foliarapplied herbicides to control weeds at 4-5 leaf stages of barnyard grass 20-25 days after seeding (DAS) in direct-seeding culture but further possible utilization of these two herbicides earlier than 3-4 leaf stages of rice were evaluated for a field where early weed infestations might be severe. The application of cyhalofop/bentazon ME and pyribenzoxim EC at right after rice emergence and the 2-3 leaf stages of rice had an excellent weed control efficacy with above 90% up to 30 DAS without a phytotoxicity of rice plant and the control efficacy of over 80% was maintained until 60 DAS. However, these two herbicides controlled Echinochloa crus-galli very effectively above 97% but Aneilema keisak and Aeschynomene indica were not controlled by cyhalofop/bentazon ME and Cyperus serotinus by pyribenzoxim EC. Therefore, to control those problem weeds, second systematic application of pyribenzoxim EC and pyrazosulfuron/mefenacet G for A. keisak and A. indica, and pyrazosulfuron/molinate G, cyhalofap/ azimsulfuron/molinate G, pyrazosulfuron/mefenacet G and bentazon SL for C. serotinus at 30 DAS was found to be very efficient herbicide systems.

• Korean Journal of Weed Science
• /
• v.18 no.1
• /
• pp.20-27
• /
• 1998

This experiments were conducted to investigate the effects of fertilizer for herbicides phytotoxicity of rice(Oryza sativa L. japonica cv Dongjin). The shoot and root growth of rice were inhibited more by pyrazosulfuron-ethyl or pyrazosulfuronethyl+molinate than bensulfuron methyl or bensulfuron methyl+dimepiperate application in nitrogen or nitrogen mixed solution. In phosphate or phosphate mixed solution, rice growth were inhibited more by bensulfuron methyl or bensulfuron methyl+dimepiperate than pyrazosulfuron-ethyl or pyrazosulfuron-ethyl+molinate application. In solution mixed with nitrogen and phosphate or fertilizer three elements, rice shoots were more. inhibited by pyrazosulfuron-ethyl or pyrazosulfuron-ethyl+molinate treatments, roots were inhibited more relatively by bensulfuron methyl or bensulfuron methyl+dimepiperate treatments. In all fertilizer solutions, rice plant heights were reduced by dimepiperate and molinate applications, but root growth was reduced only by nitrogen and phosphate mixed solution. Rice growth in sulfonylurea or their mixed herbicide application were more inhibited in high :nitrogen concentration arid by phosphate exclusion than by nitrogen exclusion culture.

• Korean Journal of Weed Science
• /
• v.18 no.2
• /
• pp.154-160
• /
• 1998

This study was conducted to develop a foliar applied herbicide mixture covering wide spectrum weeds in dry direct seeded rice. Uniform precision central composite design(UPCCD) was employed to evaluate the effect of herbicide mixture among cyhalofop-butyl(cyhalofop), bispyribenzoxim and pyrazosulfuron-ethyl(pyrazosulfuron) having different weed control spectrum and to determine the best application rates of the three herbicide mixtures. The partial additive effect was observed in the mixture of cyhalofop and bispyribenzoxim with pyrazosulfron against Echinochloa crus-galli Beauv var crus-galli L., attributed to the negative interaction between cyhalofop and bispyribenzoxim system. Additive effect was observed in the mixture of bispyribenzoxim and pyrazosulfuron against Cyperus serotinus R. and Aneilema keisak H. but cyhalofop had no effect on these weeds. The most appropriate rate of the mixture of cyhalofop with bispyribenzoxim and pyrazosulfuron was 100 : 12 : 10g ai/ha exhibiting $ED_{90}$ against three weeds such as E. crus-galli, C. serotinus and A. keisak.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.28 no.2
• /
• pp.164-172
• /
• 1983

The present study was conducted to investigate the variations in morphological traits, yield and yield-related components of rice cultivars exposed to different weather conditions by growing at the locations with different altitude but with equal latitude. Three Japonica varieties (Daegoldo, Jinheung, Shin #2) and three Tongil type semi-dwarf varieties(Josaengtongil, Suweon 287, wx 817-65-2-3) were seeded at Suweon on April 21 and transplanted at Suweon ($127^{\circ}$ N37 20', altitude 37m) and Jechun ($128.2^{\circ}$, N37 10', altitude 280-300m) on June 1 with the spacing of 30 $\times$ 15 em. The morphological traits, yield and yield-related components were measured. Culm length, paincle length and 1000-grain weight showed a little increase in Japonica varieties in Jechun as compared to those in Suweon and vice versa in semi-dwarf varieties, showing no significant differences. Number of panicles, per hill and number of spikelets per panicle among yield-related components showed remarkable increase in all varieties in Jechun as compared to those in 'Suweon but such inter-locational differences differed with varieties within varietal group and between varietal groups. On the contrary, grain fertility was higher in Suweon than that in Jechun and in Japonica varieties than that in semi-dwarf varieites , showing greater inter-locational difference in semi-dwarf varieties. Among Japonica varieties Jinheung and Shin #2 showed remarkable increase in yield in Jechun as compared to that in Suweon but in semidwarf varieties it was just the opposite. The importance of each of the yield-related component contributing to yield showed similar tendency 'regardless of locations in Japonica varieties. However, it was evidently different between locations in semidwarf varieties, where number of spikelets per panicle showed greatest direct effect on yield in Suweon but in Jechun so did grain fertility followed by the number of spikelets per panicle.