• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.6
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• pp.685-691
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• 1996

This experiment was conducted to investigate the effect of some soil conditioners, such as polyvinylalcohol(PVA), zeolite and perlite, on the changes of soil physical properties and on tobacco growth in paddy-upland rotated field. Soil conditioners were treated at the rates of 120kg in PVA, 500kg in zeolite and perlite per l0a, respectively. Ratio of soil aggregates formed from the treated plots tended to. be higher than those from the control in the order of PVA > perlite > zeolite. The wet aggregate stability, mean weight diameter, moisture retention and air permeability from the treated plots tended to be higher than those from the control. Amounts of water-stable aggregates of PV A-treated soil increased with higher soil moisture showing a peak at 50% of moisture content. But with respect to particle of size aggregate formed for crop growth and workability in field, it was presumed that 40% of soil moisture content would be most desirable. Visual characters of soil surface throughout the experiment clearly showed that treated soils were maintaining better surface roughness and porosity than control, but difference in water stable aggregates among treated plots tended to be narrowed. The growths of tobacco, espacially its root zone were better in conditioner treated plots than in non-treated plot showing best in PVA-treated soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.1
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• pp.28-33
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• 1996

This experiment was carried out at National Crop Experiment Station in 1994 to obtain basic information of growth characters and yield of rice under various seeding methods in direct seeding on dry paddy. Hwaseongbyeo sown on April 27 by flat drill seeding, high ridged drill seeding and hill seeding under different seed conditions, soil convering after seeding and irrigation methods. Nitrogen applied 150kg /ha by 3 times split application at rate of 40:30:30％ (basal: 5th leaf stage:panicle initiation stage). Seedling stands were higher in flushed irrigation water after seeding than in irrigation at 3rd leaf stage, and it also was higher in high ridged drill seedings than in flat drill seedings. Days for seedling stand, heading date were shorten 6~10 days, 2~3 days by flushed irrigation water after seeding, respectively. Number of tiller was more in high ridged drill seedings than conventional seedling method(Flat drill seeding ＋ intact seed ＋ soil covering after seeding ＋ irrigation at 3rd leaf stage after seedling stand) at early growth stage, but the most tiller number was highest in developed seeding method(Flat drill seeding ＋ soaked seed ＋ non soil covering after seeding ＋ fulshed irrigation water after seeding) at heading stage among used seeding methods. Lodging index was slightly high in high ridged drill seeding and conventional seeding. Field lodging was degree 1 in high ridged drill seedings and developed seeding, Milled rice yield in developed seeding was increased 7％ compaired with conventional seeding(5.35t /ha).

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.08a
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• pp.57-74
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• 2005

Rice yield and protein content have been shown to be highly variable across paddy fields. In order to characterize this spatial variability of rice within a field, the two-year experiments were conducted in 2002 and 2003 in a large-scale rice field of $6,600m^2$ In year 2004, an experiment was conducted to know if prescribed N for site-specific fertilizer management at panicle initiation stage (VRT) could reduce spatial variation in yield and protein content of rice while increasing yield compared to conventional uniform N topdressing (UN, ,33 kg N/ha at PIS) method. The trial field was subdivided into two parts and each part was subjected to UN and VRT treatment. Each part was schematically divided in $10\times10m$ grids for growth and yield measurement or VRT treatment. VRT nitrogen prescription for each grid was calculated based on the nitrogen (N) uptake (from panicle initiation to harvest) required for target rice protein content of $6.8\%$, natural soil N supply, and recovery of top-dressed N fertilizer. The required N uptake for target rice protein content was calculated from the equations to predict rice yield and protein content from plant growth parameters at panicle initiation stage (PIS) and N uptake from PIS to harvest. This model equations were developed from the data obtained from the previous two-year experiments. The plant growth parameters for this calculation were predicted non-destructively by canopy reflectance measurement. Soil N supply for each grid was obtained from the experiment of year 2003, and N recovery was assumed to be $60\%$ according to the previous reports. The prescribed VRT N ranged from 0 to 110kg N/ha with average of 57kg/ha that was higher than 33kg/ha of UN. The results showed that VRT application successfully worked not only to reduce spatial variability of rice yield and protein content but also to increase rough rice yield by 960kg/ha. The coefficient of variation (CV) for rice yield and protein content was reduced significantly to $8.1\%\;and\;7.1\%$ in VRT from $14.6\%\;and\;13.0\%$ in UN, respectively. And also the average protein content of milled rice in VRT showed very similar value of target protein content of $6.8\%$. Although N use efficiency of VRT compared to UN was not quantified due to lack of no N control treatment, the procedure used in this paper for VRT estimation was believed to be reliable and promising method for managing within-field spatial variability of yield and protein content. The method should be received further study before it could be practically used for site-specific crop management in large-scale rice field.

• Korean Journal of Medicinal Crop Science
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• v.7 no.4
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• pp.282-287
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• 1999

This study was conducted to investigate the effects of different soil texture in agronomic characteristics, root yield and quality of baloon flower (Platycodon grandiflorum A. DC.). Three kinds of soil texture, sandy loam, silt loam and clay loam, were tested for two years. Baloon flowers were seeded with 20cm row space and cultivated in the one square meter pot with 0. 6m depth. Fifty plants per pot were remained. In growth characteristics of one-year-old plants, shooting date was not significantly different according to the changes of soil texture. The ratio of stem growth was highest between July and August. In two-years-old plants, it was showed between May and June. Plants grown on clay loam showed the highest growing characteristics than those of other soil textures. Dry root weight cultivated on clay loam was 274kg/10a in one-year-old and 934kg/10a in two-years-old plants. The content of ethanol extracts from root was highest at those of sandy loam as 47.1 % in one-year-old root. The crude saponin content was not different significantly among the three kinds of soil texture.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.3
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• pp.295-301
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• 1996

This study was carried out to clarify the effect of sprout length, burried depth of seed and CaO$_2$ seed coating on emergence, seedling stand and early growth of rice in puddled-soil drill seeding at Junbuk in 1995. The cultivar tested was Dongjinbyeo(Japonica type). Although the longer sprouted seeds were caused the better seedling stand, 4mm sprout length of seeds appeared to be appropriate for good seedling stand and seeding uniformity, while 6mm sprouted seed resulted in ununiform seedling establishment. Rapid emergence and increased seedling stand were obtained by CaO$_2$ seed coating, which had effect more on soaked seed than on sprouted seed, but the seedling stand of sprouted seeds significantly reduced at deeper than 1cm seeding depth and also emergence rate of sprouted seeds significantly reduced at deeper than 2cm seeding depth.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.4
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• pp.246-251
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• 2017

Crop models have been used to predict a heading date for efficient management of fertilizer application. Recently, the ORYZA (v3) model was developed to improve the ORYZA2000 model, which has been used for simulation of rice growth in Korea. Still, little effort has been made to assess applicability of the ORYZA (v3) model to rice farms in Korea. The objective of this study was to evaluate reliability of heading dates predicted using the the ORYZA (v3) model, which would indicate applicability of the model to a decision support system for fertilizer application. Field experiments were conducted from 2015-2016 at the Rural Development Administration (RDA) to obtain rice phenology data. Shindongjin cultivar which is mid-late maturity type was grown under a conventional fertilizer management, e.g., application of fertilizer at the rate of 11 Kg N/10a. Another set of heading dates was obtained from annual reports at experiment farms operated by the National Institute of Crop Science and Agricultural Technology Centers in each province. The input files for the ORYZA (v3) model were prepared using weather and soil data collected from the Korean Meteorology Administration (KMA) and the Korean Soil Information System, respectively. Input parameters for crop management, e.g., transplanting date and planting density, were set to represent management used for the field experiment. The ORYZA (v3) model predicted heading date within 1 day for two seasons. The crop model also had a relatively small error in prediction of heading date for three ecotypes of rice cultivars at experiment farms where weather input data were obtained from a near-by weather station. Those results suggested that the ORYZA (v3) model would be useful for development of a decision support system for fertilizer application when reliable input data for weather variables become available.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.2
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• pp.189-195
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• 1993

This study was conducted to obtain the .basic informations for developing soybean varieties and mechanizing cultivation at the Crop Experiment Station, Rural Development Administration, Suwon, Korea in 1990. Two determinate soybean varieties, Hwangkeurnkong and Jangyeobkong, and two indeterminate soybean varieties, Clark and Williams were planted at three planting densities (33,22,16 plants / $m^2$). Number of branches and number of nodes on branches per unit area ($m^2$) were greater in determinate varieties than in indeterminate ones, and number of nodes on mainstem were greater in indeterminate varieties than in determinate ones. The higher planting density increased those characters. Seed weight per unit area ($m^2$) was higher in determinate varieties than in indeterminate ones, and it was great at the higher planting density. Indeterminate varieties showed greater mainstem dependence rate for yield components than determinate ones did. Harvest index was higher in indeterminate varieties than in determinate ones. The lower planting density increased harvest index. Stem dry weight per unit area($m^2$) was greater in determinate varieties than in indeterminate ones, and it was greater at the higher planting density. Variations among plants were great in the order of branch-related yield characters > total plant-re-lated yield characters > mainstem-related yield characters > morphological characters of mainstem and 100 seed weight. Difference between determinate and indeterminate varieties was significant in branch-related characters. Indeterminate varieties showed greater variations than determinate ones did in branch-related yield characters at different planting densities.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.383-393
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• 1991

Lodging of rice plant is the most important damage by unfavourable weather conditions in rice cultivation. High levels of nitrogen application and growing of Japonica rice variety is one factor to increase the lodging damage. Lodging of rice plant decreasing grain yield; 34% at milky. 21% at dough. 20% at yellow stage. decreasing grain Quality. increasing green rice. and increasing labor cost to harvest. To decrease lodging damage. the lodging resistant varieties will be selected and cultural practices such as amount and time of nitrogen application. planting density. water management. and disease and pest control methods have to be study for the short and strong culm. and good rooting system. Also. application methods such amount and time of plant growth regulators and new types of chemicals will be develop for the reducing lodging of rice plant. To decrease the lodging damage in direct seeding cultivation. first identifying the differences of lodging mechanisms between hand transplanting and direct seeding, second establish the suitable direct seeding methods such as seedling establishement. fertilization. and water menagement.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.180-183
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• 2001

This study was conducted to find out the effect of ripened grain and rice quality by the breeding of rice dust mite (Steneotarsonemus spinki). Growth temperature of sample (Suwon 441 and Ilpumbyeo) was maintained from 22$^{\circ}C$ (during night) to 26$^{\circ}C$ (during day) in a controlled phytotron. Plant hight and number of panicle could not showed the difference by the discoloration degree of leaf sheath. But number of spikelet was reduced affected by discoloration degree of leaf sheath. Ratio discoloration of grain was increased according to circumstances more discoloration degree of leaf sheath in Suwon 441 then Ilpumbyeo. The perfect rice grain was observed to similar Suwon 441 and Ilpumbyeo in the IV degree of ratio discoloration of grain, but less Suwon 441 than Ilpumbyeo in III and II, in such a case comparison between coloration and discoloration.

• Korean Journal of Plant Resources
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• v.21 no.1
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• pp.19-22
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• 2008

This experiment was conducted at Sangji university in Wonju, Korea from 2005 to 2006. The results obtained were summarized as follow; The Chung-ju local variety was tested to find out the possibility of transplanting of seedling as a after-barley crop. When transplanting of seedling for a after-barley crop was test, this short-day plant flowered from september 1 to september 3, showing no connection with sowing time nor seedling periods. The yield of seeds per 10a was affected by both the sowing time and the seedling periods and its peak in the plots sowed on May 15 and transplanted on June 24(40 days seedling).