• Clinical and Experimental Reproductive Medicine
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• v.16 no.1
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• pp.9-14
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• 1989

For the cryopreservation of human embryos this study was accomplished as a preliminary experiment. The purpose of this study is to obtain optimal cryoprotectant, addition and dilution method of cryoprotectant and cooling rate for raising survival of frozon and thawed 2-cell mouse embryos. Seeding was done at $-7^{\circ}C$ and the straw contained embryos was plunged at $-30^{\circ}C$ when the slow cooling was ended. Embryos those developed normally to blastocyst after in vitro culture for over 96 hours were regarded as survival ones. The survival was the rate of number of survival embryos against the recovered embryos. The results are followed : 1. The survivals were 6.3, 71.2 and 67.4% respectively, when Glycerol, DMSO and 1,2-Propanediol were used as cryoprotectant. 2. When sucrose was added in freezing solution, the survival was 69.0%. That was higher than the survival of embryos frozen without sucrose in freezing solution. The difference was not significant. 3. Addition and dilution of cryoprotectant by 4 stepwise raised the survival than by direct, but that was not significant. 4. When embryos were frozen by -0.3, -0.5 and $-1^{\circ}C/min$ before plunged into $LN_2$, the survivals were 67.9, 78.0 and 37.0% respectively. The differnce was significant.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.334-334
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• 2017

Unstable soil moisture conditions often negatively affect the emergence, seedling establishment, and growth uniformity at the initial stage, and then reduce the grain yield and biomass in direct seeding cultivation for rice in rainfed fields. Therefore it is important to develop a technique to increase the rapid and stabilized seedling establishment and improve the uniformity of initial growth after sowing. This study aims to confirm results on seed priming effect of indoor using petri dish experiments can be reproduced in the field using container at Ghana. Twenty-seven rice varieties including of Oryza sativa L. and O. glaberrima Steud. were used in this study. The experiments using petri dish and container with different soil moisture conditions (5%, 10%, 15%, 20%) were compared. As a result, a significant positive correlation was found between the germination time uniformity in the primed seed of petri dish and emergence time uniformity in the primed seed of container in 10% and 15% soil moisture condition. A significant positive correlation was found between the germination time uniformity in the primed seed of petri dish and plant height in the primed seed of container in 10% soil moisture condition in O. glaberrima. This study concluded that the priming effect in petri dish demonstrate those in container in the field condition of Ghana in 10% and 15% soil moisture condition during seedling stage.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.53-53
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• 2017

Unstable soil moisture conditions often negatively affect the emergence, seedling establishment, and growth uniformity at the initial stage, and then reduce the grain yield and biomass in direct seeding cultivation for rice in rainfed fields. Therefore it is important to develop a technique to increase the rapid and stabilized seedling establishment and improve the uniformity of initial growth after sowing. This study aims to confirm results on seed priming effect of indoor using petri dish experiments can be reproduced in the field using container at Ghana. Twenty-seven rice varieties including of Oryza sativa L. and O. glaberrima Steud. were used in this study. The experiments using petri dish and container with different soil moisture conditions (5%, 10%, 15%, 20%) were compared. As a result, a significant positive correlation was found between the germination time uniformity in the primed seed of petri dish and emergence time uniformity in the primed seed of container in 10% and 15% soil moisture condition. A significant positive correlation was found between the germination time uniformity in the primed seed of petri dish and plant height in the primed seed of container in 10% soil moisture condition in O. glaberrima. This study concluded that the priming effect in petri dish demonstrate those in container in the field condition of Ghana in 10% and 15% soil moisture condition during seedling stage.

• Weed & Turfgrass Science
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• v.7 no.2
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• pp.120-129
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• 2018

This experiment was conducted to find the most suitable crop establishment method and weed management practices for transplanted aman rice in Bangladesh. Rice variety Bangladesh Rice Research Institute (BRRI) dhan44 was used as planting materials where three crop establishment methods ($T_1$: direct wet seeding by drum seeder; $T_2$: hand broadcasting; $T_3$: transplanting) and four weeding options ($W_1$: Hand weeding (HW); $W_2$: BRRI weeder+HW; $W_3$: Herbicide+HW; and $W_4$: no weeding) were tested. Among the crop establishment methods, the highest grain yield ($5.12t\;ha^{-1}$) was obtained with the $T_3$, while the highest benefit cost ratio (BCR) of 2.08 was found in $T_2$. In case of the weed management method, $W_1$ showed superior results on the plant $density/m^2$ (139.66) at 60 days after transplanting (DAT), grain yield ($4.97t\;ha^{-1}$), and BCR (2.03). On the other hand, the highest plant dry matter (36.20 g) at 60 DAT and the highest yield ($6.10t\;ha^{-1}$) were obtained in a $T_3W_1$ combination. The results of this study show that the productivity of rice during aman season could be most significantly increased with the use of transplanting ($T_3$) alone, hand weeding ($W_1$) alone, or a combination of the two methods ($T_3W_1$).

• Weed & Turfgrass Science
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• v.3 no.1
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• pp.6-12
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• 2014

The survey of weed occurrence was conducted to identify problem weed species in the paddy field. The 320 sites of the 13 regions in Gyeongbuk Province were investigated from June to July, 2013. In the whole region, 51 weed species were identified including 34 annuals and 17 perennials. The highest importance value of annual weed and perennial was dominant 88.4 and 48.7%, in Gumi region, respectively. The most dominant weed species in paddy fields of Gyeongbuk Province were Monochoria vaginalis var. plantaginea (10.80%), followed by Lemna paucicostata (10.74%), Bidens tripartite (8.77%), Echinochloa oryzoides (7.17%), and Scirpus juncoides (6.20%). The similarity of paddy weeds in 13 regions observed through TWINSPAN analysis was distinguished by Ludwigia prostrata, Scirpus juncoides, Lindernia dubia, Polygonum aviculare, and Alopecurus aequalis var. amurensis. The weed species, Ludwigia prostrata, was divided into the four regions, Gyeongju, Gumi(direct seeding cultivation), Youngcheon and Euiseong and ten regions, Gumi, Bonghwa, Sanju, Goryung, Youngdeog, Pohang, Sanju, Andong, Yecheon, and Cheongdo.

• Applied Biological Chemistry
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• v.47 no.3
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• pp.361-365
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• 2004

Chitin and its derivatives have been introduced to tomato seedlings by direct mixing of chitin, chitosan, or chitooligosaccharides (CO) with soils, watering of chitosan or CO solutions to soils, or chitosan-coating of tomato seeds as a biomodulator of plant growth, and the growth of tomato plants was measured 30- and 45-day after seeding in the pots. The treatment of chitin and its derivatives promoted the growth of tomato plants in plant heights, shoot weight, maximum leaf length and number of leaves. By comparison in the contents of cellular inorganic nutrients in the plants, it was found out that chitin or chitosan treatments accelerated nitrogen and potassium uptake but inhibit calcium uptake, suggesting that chitin and its derivatives modulate absorption of inorganic nutrients through plant roots from environment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.1
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• pp.1-7
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• 2003

In spite water direct seeding cultivation of rice has advantages in terms of laborsaving and cost-down, it demonstrates uneven seedling establishment and difficult weed management. To select an applicable mat for mulching system of water seeded rice, weed occurrence, growth and yield performances of rice, and soil temperature were evaluated in several kinds of biodegradable mulching material. Field studies were conducted at the experimental farm of National Crop Experiment Station in 1999 and 2000. Among the mats tested in 1999, Safer-mat had the greatest effect on inhibiting weed occurrence and Lawn-mat demonstrated the least efficacy of weed control (EWC) value. In Safer-mat treatment, Ludwigia prostrata was the dominant weed species but Echinochloa crus-galli was not observed. Different kinds of mulching material from the mats studied in 1999 were tested in 2000. Biodegradable polyester (PES) coated on the recycled paper for newspaper press (RP) treatments showed similar or higher EWC values than non-mulched broadcast seed rice with 2 times of herbicide application (BC-herbicide) and Safer-mat that was the most effective mat on preventing weed appearance in 1999. Immediately after mat mulching on the surface of paddy soil, five pregerminated rice seeds were manually sown in each 3cm-hole formerly punctured at 30${\times}$14 cm spacing in 2000. All the 3 kinds of mulching material tested in 2000 had better seedling stand than BC-herbicide treatment. Rice yield in PES coated with 10 thickness on RP (PES10 $\mu\textrm{m}$＋RP) was a little higher than in BC-herbicide treatment but the former produced less panicles in unit land area than the latter. PES10 $\mu\textrm{m}$＋RP demonstrated a great effect on raising soil surface temperature than non-mulching treatment throughout the period of seedling establishment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.2
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• pp.128-133
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• 1993

This experiment was carried out to evaluate the germination characteristics of Korean red rice seeds. Ten lines of the long grain and ten lines of the short grain Korean red rices were tested for dormancy, shoot emergence rate at different water and soil depth. Both the long and short grain type seeds of Korean red rice germinated over than 99% immediately after harvest, so that no dormancy was observed in the Korean red rices. Shoot emergence rate of the long grain red rices at 7cm of water depth and that of the short grain red rices at 11cm were 83.3% and 83.5% respectively, while those of the indica check Samgangbyeo and japonica check Seomjinbyeo were 0%. Shoot emergence rates of the long and short grain red rices at 7cm of soil depth were 71.1% and 73.9% respectively, while those of the check varieties Samgangbyeo and Seomjinbyeo were 40.0% and 28.0% respectively. Thus, the Korean red rices were expected to be useful germplasm source for direct seeding.

• Journal of Biosystems Engineering
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• v.37 no.6
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• pp.335-341
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• 2012

Purpose: While an unmanned helicopter has been extensively used for spraying chemicals on agricultural crops, its low utilization (two months per year from July to August) has recently become an issue. This study aimed to increase the utilization of the unmanned helicopter. The centrifugal rice seeder, a mounting device for rice seeding for unmanned helicopter was developed and assessed its performance. Methods: The concept of the centrifugal spraying device was to obtain design criteria for centrifugal distribution. Four types of blade shapes namely straight, curved, straight wing and curved wing were developed and used. The rotational speed of the blades was tested at 1,000, 1,200 and 1,400 rpm. Results: The blade shapes, rotational blade speed and angle of trajectory were theoretically analyzed and results were validated with a series of laboratory experiments. Conclusions: The curved wing blades provided the distribution uniformity (DU) at 1,200rpm of rotational speed and 60 degree of seed drop point. The spray uniformity of 4.2% was also achieved.

• Korean Journal of Medicinal Crop Science
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• v.7 no.1
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• pp.22-26
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• 1999

This study was investigated to elucidate the growth characteristics of Acanthopanax sessiliflorus grown under different conditions and seasons. The emergence percent of seeds sown in the vinyl house was about 2.2 times better than that in the open field. The plants which had 2 to 3 normal leaves showed the highest value in root setting percent, and the root setting percent was decreased significantly in plants with one normal leaf and 4 to 5 normal leaves. The root setting percent of plants transplanted from April 19 to May 2 was 100%, but plants transplanted at April 4 or from May 17 to June 1 showed lower root setting. Tree percent, plant height. root length and fresh weight of plants grown by transplanting culture were better than those of plants grown by direct seeding.