• Korean Journal of Weed Science
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• v.8 no.2
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• pp.208-216
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• 1988

This study was conducted to select herbicides safe for cucurbitaceae crops under the polyethylene film mulching culture. No crop injury with ethalfluralin (N-ethyl-N-(2-methylally)-2, 6-dinitro-4-(trifluoromethyl) aniline) was found in gourd, water melon, cantaloup, cucumber and pumpkin of direct seeded culture. There was no significant reduction in fresh weight of gourd and pumpkin at the rate of 1080 g a.i./ha, that of water melon, cantaloup and cucumber at the rate of 720 g a.i./ha. Napropamide (N,N-diethyl-2-(${\alpha}$-naphthyloxy) propionamide) did not cause any crop injury at the rate of 1500 to 3000 g a.i./ha. There was no significant reduction in fresh weight of gourd, pumpkin and cucumber at the rate of 3000 g a.i./ha, and that of cantaloup and water melon at the rate of 1500 g a.i./ha. Trifluralin (${\alpha}$, ${\alpha}$, ${\alpha}$-trifluoro-2,6-dinitro-N, N-diprophlaniline) did not cause any crop injury in gourd. When ethalfluralin, napropamide and nitralin were applied to the transplanted seedlings of water melon and cantaloup, no significant reduction in the fresh weight were observed. The weeding effect greater than 90% was obtained with ethalfluralin at 720 to 1080 g a.i./ha and pendimethalin (N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine) at 1268 g a.i./ha. The rest treatment gave the weeding effect ranging from 81 to 90%.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 1997.05a
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• pp.27-34
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• 1997

Bovine oocytes surrounded with compact cumulus cells were cultured for 20 to 22 hours($38^{\circ}C$, 5% $CO_2$) in modified TCM-199 medium supplemented with 5% superovulated cow serum(SCS) and inseminated by in vitro capacitated spermatozoa. Day 7 to 8 embryos were equilibrated for 10 minutes in 1.3M methyl cellosolve(MC) <1.1M diethylene glycol(DEG), 1.8M ethylene glycol(EG), 1.6M propylene glycol(PG) and 1.1 M 1,3-butylene glycol(BG) solutions. They were then loaded into 0.25ml straws, placed into an alcohol bath freezer at $0^{\circ}C$, cooled from $0^{\circ}C$ to $-6^{\circ}C$ at $-1^{\circ}C$/minute, seeded, held for 10 minutes, and stored in liquid nitrogen. After thawing in $30^{\circ}C$ water, the embryos wee rehydrated in TCM-199 medium and then cultured for 48 hours in TCM-199 plus 5% SCS. Embryos were considered viable if they progressed to later developmental stages with a good morphology. Some of the embryos frozen in each cryoprotectant were thawed and transferred non-surgically without removing the cryoprotectant. Hatched embryos survived freezing and one-step dilution as follows : EG(50.0%), MC(53.6%), DEG(56.9%), PG(58.0%) and BG(11.5%). The survival rate of embryos cooled at -0.3^{\circ}C$ vs. $-0.5^{\circ}C$/minute was not significantly different(P<0.05), however, blastocysts hatched most often (P<0.01) in vitro when cooled at a rate of $0.3^{\circ}C$/minute(64.6%), 31/48) than at $-0.5^{\circ}C$/minute(22.6%, 12/53). Pregnancy rates resulting from embryos frozen in the different cryoprotectants were as follows : MC(48%, 10/21); DEG(30%, 3/10); EG(74%, 20/27); and PG(40%, 4/10). These results indicate that MC, DEG, EG and PG have utility as cryoprotectants for the freezing and thawing of IVF Bovine embryos.

• Korean Journal of Weed Science
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• v.18 no.3
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• pp.225-236
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• 1998

KSC-13906 [Erythro N-{(4,6-dimethoxypyrimidin-2-yl)aminocarbonyl} -2-(2-fluoro-1-hydroxy-n-propyl) benzenesulfonamide, US Patent 5,461,025] was investigated how can control phytotoxicity fluctuation and what a good method apply to new rice herbicide. The growth inhibition was observed when the rice plants was transplanted at a shallow depth(0 - 1cm) and leaching was low(0 - 1cm/ day) from the paddy soil. KSC-13906 appeared to move readily down into the paddy soil with water by 3cm depth in the soil column(${\phi}$ 10cm) filled with loamy sand soil under 3cm/day of leaching condition. Artificial control releasing pattern, designed as treated with KSC-13906 of 9 or 18g ai/ha either at a once or daily treated dividing volume of 1/20, 1/25 and 1/30 of the total volume, increased the safety of KSC-13906 to direct seeded and transplanted rice. The safety of KSC-13906 was also enhanced when KSC-13906 was mixed with dymron. For example, the mixture of KSC-13906 and dymron effectively reduced injury of direct seeded rice plants at 18 and 500g ai/ha, respectively, treated 7 days after transplanting. However, combination of KSC-13906 and several herbicides didn't show any synergistic effetct on herbicidal activity and safening effect on rice. However, the combination of KSC-13906+dymron (9~12+250~500g ai/ha) or KSC-13906+mefenacet+dymron(9+250+250g ai/ha) controlled almost all weeds in paddy field without causing any injury to rice and thus the combination would successfully be used as an oneshot herbicide in rice culture.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.18
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• pp.54-87
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• 1975

The effects of various weather factors on yield components of rice, year variation of yield components within regions, and regional differences of yield components within year were investigated at three Crop Experiment Stations O.R.D., Suweon, Iri, Milyang, and at nine provincial Offices of Rural Development for eight years from 1966 to 1973 for the purpose of providing information required in improving cultural practices and predicting the yield level of rice. The experimental results analyzed by standard partial regression analysis are summarized as follows: 1. When rice was grown in ordinary seasonal culture the number of panicles greatly affected rice yield compared to other yield components. However, when rice was seeded in ordinary season and transplanted late, and transplanted in ordinary season in the northern area the ratio of ripening was closely related to the rice yield. 2. The number of panicles showed the greatest year variation when the Jinheung variety was grown in the northern area. The ripening ratio or 1, 000 grain weight also greatly varied due to years. However, the number of spikelets per unit area showed the greatest effects on yield of the Tongil variety. 2. Regional variation of yield components was classified into five groups; 1) Vegetation dependable type (V), 2) Partial vegetation dependable type (P), 3) Medium type (M), 4) Partial ripening dependable type (P.R), and 5) Ripening dependable type (R). In general, the number of kernel of rice in the southern area showed the greatest partial regression coefficient among yield components. However, in the mid-northern part of country the ripening ratio was one of the component!; affecting rice yield most. 4. A multivariate equation was obtained for both normal planting and late planting by log-transforming from the multiplication of each component of four yield components to additive fashion. It revealed that a more accurate yield could be estimated from the above equation in both cases of ordinary seasonal culture and late transplanting. 5. A highly positive correlation coefficient was obtained between the number of tillers from 20 days after transplanting and the number of panicles at each(tillering) stage 20 days after transplanting in normal planting and late planting methods. 6. A close relationship was found between the number of panicles and weather factors 21 to 30 days, after transplanting. 7. The average temperature 31 to 40 days after transplanting was greatly responsible for the maximum number of tillers while the number of duration of sunshine hours per day 11 to 30 days after transplantation was responsible for that character. The effect of water temperature was negligible. 8. No reasonable prediction for number of panicles was calculated from using either number of tillers or climatic factors. The number of panicles could early be estimated formulating a multiple equation using number of tillers 20 days after transplantation and maximum temperature, temperature range and duration of sunshine for the period of 20 days from 20 to 40 days after transplantation. 9. The effects of maximum temperature and day length 25 to 34 days before heading, on kernel number per panicle, were great in the mid-northern area. However, the minimum temperature and day length greatly affected the kernel number per panicle in the southern area. The maximum temperature had a negative relationship with the kernel number per panicle in the southern area. 10. The maximum temperature was highly responsible for an increased ripening ratio. On the other hand, the minimum temperature at pre-heading and early ripening stages showed an adverse effect on ripening ratio. 11. The 1, 000 grain weight was greatly affected by the maximum temperature during pre- or mid-ripening stage and was negatively associated with the minimum temperature over the entire ripening period.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.254-261
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• 1995

The nationwide weed survey was conducted in lowland rice fields over whole country of Korea in 1992 in order to determine a change of weed community and to identify a major dominant weed species and/or problem weed. Based on morphological characteristics of weeds, population ratio of broad leaf weed was 42.6%, grasses weed-9.0%, sedges-33.4% and others were 15.0%. Annual weed was 33.4% while perennial weed was 66.6% in terms of life cycle of weeds. Meanwhile, there was different weed occurrence as affected by planting method of the rice plant. In hand transplanted paddy fields predominant weed species was Sagittaria trifolia L., Monochoria vaginalis Presl., and Aneilema japonica Kunth. In machine transplanted rice fields of infant and young rice seedling Eleocharis kuroguwai Ohwi. and S. trifolia L. were more predominant. There was high occurrence of M. vaginalis, Echinochloa crus-galli L., and Leesia japonica Makino in water seeding while E. crus-galli and Cyperus serotinus Rottb. were predominant weed species in dry seeded rice. Monoculture of the rice plant would cause to high occurrence of E. kuroguwai, S. trifolia, M. vaginalis, E. crus-galli, and Sagittaria pygmaea Miq and there was higher population of S. trifolia, S. pygmaea, M. vaginalis, E crus-galli, and E. kuroguwai in double cropping system based on rice culture. In particular, there was high different weed occurrence under different transplanting times. E. kuroguwai, S. trifolia, S. pygmaea, M. vaginalis, and C. serotinus were higher population at the transplanting of 25 May and S. trifolia, E crus-galli, C. serotinus, and M. vaginalis at 10 June and S. pygmaea, E. kuroguwai, M. vaginalis, S. trifolia, and E. crusgalli at 25 June in Korea, respectively. Autumn tillage in terms of tillage time would cause more predominant weed species such as S. trifolia, E. kuroguwai, M. vaginalis, and S. pygmaea while spring tillage was higher population of E. kuroguwai, S. trifolia, E. crusgalli, M. vaginalis, and S. pygmaea. In plain area of paddy field there was higher occurrence of E. kuroguwai, S. trifolia, M. vaginalis, E. crus-galli, and S. pygmaea and in mid-mountainous area S. trifolia, E. kuroguwai, M. vaginalis, E. crus-galli, and Ludwigia prostrate Roxb. while in mountainous area S. trifolia, M. vaginalis, Potamogeton distinctus Ben., E. kuroguwai, and E. crus-galli were. In 1992 the most ten predominant weed species at the rice field of Korea based on summed dominant ratio(SDR) were E. kuroguwai > S. trifolia > E. crus-galli > M. vaginalis > S. pygmaea > C. serotinus > L. prostrate > P. distinctus > A. japonica > Scirpus juncoides Roxb.