• Plant Resources
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• v.4 no.1
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• pp.6-12
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• 2001

Growth and yield of licorice were investigated under the different conditions of ridge height, planting density, and irrigation in order to establish its cultural practices for the domestic production with the aim to substitute the import. Seedlings were grown under low ridge(20cm) and high ridge(40cm) in low density plot(60$\times$30cm) and high density plot(40$\times$30cm), respectively. The low ridge cultivation of large seedlings increased plant height and root length under low density, and stem and root diameter under high density compared to the high ridge cultivation. In the high ridge cultivation, high density plot was 1.1 to 1.3 times in plant height, root length, stem and root diameter as high as low density one. Fresh and dry weight of plant and root in high ridge were 1.3 to 1.5 times as high as those in low one. The growth of small seedlings(4~10g) were generally poor compared to that of large seedlings. High density plot in low ridge showed the good growth characteristics including plant height, root length, stem and root diameter, and number of branch. High density plot was 1.4 to 1.6 times in fresh and dry weight of plant and root as high as low density plot. In the seasonal changes of growth under various irrigation regimes, the twice irrigation a day produced the more number of leaf than the other regimes since around 46 days after transplanting. The former irrigation resulted in 1.2 to 1.4 times in plant height as long as the other irrigations around 26 days after transplanting and then the difference was increased to 1.6 to 2.0 times around 64 days after transplanting. Under the twice irrigation a day, plant height, root length, stem diameter, root diameter, number of leaf, fresh plant weight, dry plant weight, fresh root weight, dry root weight were 1.6 to 2.0, 1.1, 1.2 to 1.6, 1.3 to 1.8, 1.9 to 2.7, 1.7 to 8.0, 1.6 to 2.8,2.0 to 3.0, 1.6 to 2.7 times as high as those under the other irrigation regimes, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.283-288
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• 1982

This experiment was carried out to improve the cultural practices of seedlings and to investigate the proper planting density in aromatic tobacco, Sohang. Two different cultural practices of seedling were employed; Temporary transplanting (TT; Conventional practices) and non temporary transplanting (N.T.). Vinyl pot sizes were $3.5cm{\times}3.5cm, \;4cm{\times}4cm$ and $5cm{\times}5cm$ Plants per hole were 1, 3, 5, 7 and 9. There were little difference among the vinyl pot sizes in all characters except the survival ratio. But it may be little problem on cultural practices by 7 plants per hole in $5cm\times$5cm vinyl pot. There were not significant in price per kg, yield per 10a and value per 10a between two cultural practices of seedlings and among three pot sizes. Mildness and filling power were increased by increasing the plants per hole. Combustibility of 5-9 plants were better than those of 1-3 plants per hole. The growing of 6 seedlings per hole in $5cm\times$5cm vinyl pot by non temporary transplanting resulted the best cultural practices for an aromatic tobacco, Sohyang.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.60-73
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• 1989

Two field experiments were carried out to assess the applicability of a central composite design (CCD) in determining optimum culture condition of an early rice cultivar, Unbongbyeo in southern Korea. A central composite design with two replicates was applied to five levels of five factors such as the number of hills per 3.3m2, the number of seedlings per hill, the levels of nitrogen, the transplanting date and the seedling age (Experiment 1). The levels of planting density were ranged from 30 hills to 150 hills per 3.3m2 ; the number of seedlings per hill from 1 seedling to 9 seedlings per hill; the levels of nitrogen application from 1 kg/l0a to 21 kg/l0a; the transplanting date from June 15 to July 5; the seedling age from 25 days to 45 days. A fractional factorial design was applied to three levels of five factors tested in CCD (Experiment 2). Yield per hill and per unit area were examined and the results obtained from both experiments were compared. The benefits from the central composite design were discussed. Maximum yield of brown rice per unit area was obtained at the combination of the central levels of one of five factors when the other four factors were fixed at central point. Furthermore, brown rice yield per unit area affected by interaction of two factors was maximized at the central point when the remain three factors being fixed at the central level. The responses of five factors to brown rice yield per hill and unit area were found to be a saddle point in both designs. Actual values of the stationary points were 107 hills per 3.3 m2, 4 seedlings per hill, 10 kg nitrogen per l0a, transplanting date of rice on June 26 and 33 days of seedling age in the central composite design. Brown rice yield per unit area at the stationary points were estimated 439 kg/l0a in the central composite design and 442 kg/l0a in the fractional factorial design. Considering the number of experimental treatment combinations, the central composite design was rather convenient in reducing the number of treatment combinations for similar information. It was more convenient for an experimenter to present the results from the central composite design than those from the fractional factorial design. Considering the optimum yields of brown rice per unit area at the stationary points being verified as saddle points in both designs. inter-heterogeneity of each of the factors should be avoided in setting up factors in pursuit of inducing unidirectional response of the factors to yield. Even though both the lower and higher levels in the central composite design being beyond the region of an experimenter's interest. they were considered highly valued in interpretation of the results. Conclusively. the central composite design was found to be more beneficial to optimize culture condition of paddy rice even with several levels of various factors were involved.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.4
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• pp.407-415
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• 2009

To investigate the effects of seeding date, nursery days and plug cell size on seedling growth and quality of waxy corn. This study was carried out in the field of the National Institute of Crop Science in 2007. Varieties used were two waxy corn hybrids cvs. Chalok# 1 and Chalok# 4. The plant height, number of leaves and dry weight of waxy corn seedlings were significantly affected by seeding dates and plug cell size, while no differences between varieties. The growth of seedlings was faster in March 14 seeding than in May 8 and July 4 seedings. Based on plant height, March 14 seeding, May 8 seeding and July 3 seeding reached suitable size for transplanting after 30 days (21.6cm), 15 days (25.5~26.9cm) and 10 days (21.6~24.0cm) in the nursery, respectively. Seedlings of March 14 seedling and May 8 and July 3 seeding reached suitable number of leaves i,e. 2~3 leaves, 15~20 days after seeding on March 14 and 10 days after seeding on May 8 and July 3. Dry weights of 30 days seedling for March 14 seeding, 20 days seedling for May 8 seeding and 15 days seedling for July 3 seeding were 0.43g, 0.57~0.67g and 0.53g, respectively, and the dry weight of seedlings increased by 2~3 folds at the later nursery days. The suitable nursery days of waxy corn were 20 days on March 14 seeding and 10~15 days on May 8 or July 3 seeding.

• The Korean Journal of Mycology
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• v.13 no.1
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• pp.23-26
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• 1985

Percentage of Bakanae infection of rice seedlings grown in nursery box was higher than rice seedlings grown in protected semi-irrigated nursery regardless of seed treatment. Rice seedlings grown in nursery box had higher Bakanae symptom ratio than that of the rice seedlings grown in protected semi-irrigated nursery in the paddy field conditions after transplanting. Grain yield of rice transplanted from nursery box was lower than that of the rice in protected semi-irrigated nursery.

• Journal of the Korean Society of Tobacco Science
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• v.15 no.1
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• pp.15-25
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• 1993

The severities of major tobacco diseases had been surveyed throughout northern Kyeongbuk, a major flue-cured tobacco growing district in Korea, in relation to the actual control method used by the farmers in 1992. At seedling stage, anthracnose caused by Colletotrichum nicotianae was major disease of the plant due to poor damage of the temporary transplanting pots. Mosaic caused by tobacco mosaic virus(TMV) was very severe in certain of greenhouses. Although viral disease caused by TMV, cucumber mosaic virus(CMV) and by potato virus Y(PVY) were severe in fields, but mosaic by TMV was major of the diseases. Potato virus Y was found later than that in Honam district. The late occurrence of the disease might be caused the difference between cultivating method of potato plants in northern Kyeongbuk and that in Honam district. In fields suffered from hail disaster, the damage of tobacco plants by angular leaf spot was severe. Most of tobacco growers had wrong information about the practical methods not only of milk treatment for the protection of the plants from TMV, but also of fungicide applications for the control of other major diseases. It suggested that education on the methods to the farmers must be very important for control of the diseases.

• Journal of Biosystems Engineering
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• v.14 no.3
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• pp.181-187
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• 1989

The mechanical and rheological properties of agricultural materials which influence the machine design or handling are not completely understood. Agricultural materials do not react in a purely elastic manner, and their responses when subjected to stress and strain appear a combination of elastic and viscous behavior. Many researchers have studied the mechanical and rheological properties of the various agricultural materials, but those properties are available mostly for foreign varieties of agricultural products. Rheological properties of rice seedlings become important to formulate the principles governing their mechanical behavior. The objectives of this study were to experimentally determine the creep and recovery behavior of rice seedlings of one japonica-type and one Indica x japonica hybrid in the transplanting age. The results of this study are summarized as follows; 1. The compression creep and recovery behavior of mat-type seedlings could be described by 4-element Burger's model. 2. The steady-state creep appeared at the stress larger than 0.8 MPa and the logarithmic creep appeared at the stress smaller than 0.8 MPa. 3. In the compression creep test of the rice seedlings, the instantaneous elastic modulus of Burger's model showed the range from 20 to 40 MPa. The higher value of absolute viscosity for the rice seedling explained that the rice seedlings were viscoelastic materials. 4. In the recovery test of the rice seedlings, there was a tendency that the higher permanent strain of all samples was observed under the smaller stress being appeared, and the larger permanent strain in Dongjin was observed than in Samkang.

• Korean Journal of Organic Agriculture
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• v.7 no.2
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• pp.153-161
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• 1999

No-till direct-sown rice-wheat relaying cropping system has major advantages such as labor and cost saving by eliminating tillage and preparation of seed bed and transplanting. In this system, rice sowing was done simultaneously wheat harvesting. A paddy field experiment was conducted to evaluate effects of no-till years on soil microbial changes and soil physico-chemical characteristics with rice growth and development. Chemical fertilizers and agricultrual chemicals was not applied in no-till system. As the year in no-till direct-sown system the air permeability was increased and after water submerging soluble nitrogen was released Aerobic microbial-n was highest in May and then decreased after water irrigation. The population of aerobic soil microorganisms were steeply decreased after water submerging Soil microorganisms was decreased with the increased the soil depth. A month was needed for the seedling establishment in a no-tillage rice-wheat cropping system. Increased cropping years improved leaf greenness and leaf area index(LAI). But stomatal conductance(Gc) was higher in conventional cultivation system than no-till system. Stomatal conductance at panicle initiation stage was increased higher in conventional condition of leaves but the difference between conventional and no-till system was increased at heading stage. In no-till 4 years condition rice grain yield was spikelet numbers per panicle.

• Korean Journal of Medicinal Crop Science
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• v.6 no.2
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• pp.102-107
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• 1998

Solomon's seal (Polygonatum odoratum) seedlings raised through its seeds can replace the rhizomes impelling higher cost for transplanting, This experiment was done to determine the seed characteristics and the germinating processes to give some information on bulk production of seedlings using the seeds. The external or internal morphology of seeds or seedlings grown in lab. or greenhouse was examined mainly with stereomicroscope. The external shape of Solomon's seal seed was hard seed-coat and orthotropous ovule with linear type embryo stretching to the center of seed. Germination proceeded through the several steps. The lower part of seed embryo having the primordia of bulbil and roots first grew before the bulbil and roots was developed from the primordia. The lower part of embryo was enlarged toward the endosperm of seed as soon as seed germinated. Then epicotyl was formed on the apex of bulbil. The epicotyl was elongated after at least 6-week chilling treatment for breaking its dormancy and the first leaf shape was affected by light intensity given during seedling emergence. The bulbil was the first organ of the rhizome used as tea or herb medicine.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.2
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• pp.100-104
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• 1989

This study was carried out in order to develop a compound fertilizer for raising rice seedling in trays. A compound fertilizer, a trail product, was manufactured using the major fertilizer sources of ammonium sulfate, diammonium phosphate and potassium chloride in combination with zeolite and glutamic acid fermentation waste. Besides, polyacrylamide for slow release control of the fertilzer and Tachigaren and sulfuric acid for reducing the occurrence of seedling rot were used. The component ratios of N, $P_2O_5$ and $K_2O$ of trial product were 4.19, 5.41 and 4.05 percent respectively. The dissolution rate of nitrogen component in water for the trial product with polyacrylamide was lower about fifteen percents than the product without polyacylamide in six hours. Hymexazole, main component of Thachigaren, from the product was released about 86.2 percents in forty eight hours. When the product with polyacylamide applied on red earth soil and paddy soil, the pH of soil ranged from 4.6 to 5.4 for 25 days experiment.