• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.3
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• pp.190-194
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• 2000

Double cropping is important for increase of farm income and rate of arable land utilization. This study was carried out to obtain information for optimum plant density of the second crop in a double cropping system. A waxy corn hybrid, Chalok #2, was sown on July 10 at the first corn cropping site. Growth characteristics and yield response of fresh waxy corn were examined under different planting densities, which were 55.5, 66.6, 83.3, and 111.1 thousands plants ${ha}^{-1}$. Plant height was higher under high planting density than low planting density and 154cm at the 55.5 thousand plants ${ha}^{-1}$, and 168cm at the 111.1 thousand plant ${ha}^{-1}$. It showed same trends in ear height and gravity center height. But planting density did not affect root lodging and silking date. At the silking stage, stalk and leaf dry matter weight and leaf area index (LAI) were increased significantly with increasing planting density, Filled ear lengtg was shortened significantly under the hi임est planting density (111.1 thousand plants ${ha}^{-1}$), while ear length and ear diameter were no differences among planting densities. The number of marketable ears increased with increasing planting density, but husked fresh ear weight was the highest at 83.3 thousand plants ${ha}^{-1}$ with 11.2MT ${ha}^{-1}$and optimum planting density was estimated as about 80 thousand plants ${ha}^{-1}$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.6
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• pp.457-462
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• 2004

Lodging is one of the most serious problems in soybean cultivation. Therefore, improved cultural methods to reduce lodging as well as to increase photosynthetic ability should be mostly desirable to increase soybean production. The test variety was 'Hwangkeumkong' which was pinched at V7 stage. The greatest difference in canopy height between rows was shown when every other row was pinched, which also recorded the most effective reduction in lodging. The 9th leaf of soybean plants in non-pinching rows of alternative non-pinching and pinching plot showed the highest photosynthetic ability due to the greatest difference in canopy height. Although leaf area index was higher in pinched rows in average after 17 August, alternative pinching of every other row recorded the highest LAI on 5 September. Alternative pinching of every other row resulted $2\~14\%$ higher yield than non-pinching or complete pinching due to the increases of number of grains in the upper part of main stem and average grain weight of non-pinching rows and in alternative pinching.

• Spatial Information Research
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• v.18 no.4
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• pp.109-120
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• 2010

Recently, due to rapid increasement of spatial data collected from various geosensors in u-GIS environments, the importance of spatial index for efficient search of large spatial data is rising gradually. Especially, researches based R-Tree to improve search performance of spatial data have been actively performed. These previous researches focus on reducing overlaps between nodes or the height of the R -Tree. However, these can not solve an unnecessary node access problem efficiently occurred in tree traversal. In this paper, we propose a MR-Tree(Mapping-based R-Tree) to solve this problem and to support efficient search of large spatial data. The MR-Tree can improve search performance by using a mapping tree for direct access to leaf nodes of the R-Tree without tree traversal. The mapping tree is composed with MBRs and pointers of R-Tree leaf nodes associating each partition which is made by splitting data area repeatedly along dimensions. Especially, the MR-Tree can be adopted in various variations of the R-Tree easily without a modification of the R-Tree structure. In addition, because the mapping tree is constructed in main memory, search time can be greatly reduced. Finally, we proved superiority of MR-Tree performance through experiments.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.183-183
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• 2017

In the early part of rice growth, root volume primarily limits the amount of plant-accessible nitrogen (N). Therefore, knowledge of the root development is important for modeling N uptake of rice. The timing when the volume of rhizosphere cover the whole soil is also important to carry out timely top dressing. However, information about initial root expansion and associated N uptake is limited due to intrinsic technical difficulties in assessing below-ground processes. Some studies, however, showed a close relationship between below-ground root and above-ground leaf development, suggesting a possibility that above-ground attributes could serve as surrogates for the root processes. In this study, we investigated the relationship between below-ground and above-ground development of rice. Field experiments were conducted where we cultivated Koshihikari (a leading cultivar in Japan) for four different cropping schedules in 2012. In 2016, Gimbozu (HEG4) and three flowering time mutant lines of Gimbozu (X61 (se13), HS276 (ef7), DMG9 (se13, ef7)) were examined for a single season. Experiments were performed with three replications in a completely randomized design. We monitored ammonium-N concentration ([NH4+-N]) in soil solution by repeatedly taking samples from a porous tubing (10-cm long) vertically inserted at the most distant point from surrounding rice hills. Samples were taken in triplicate (= triplicate tubes) and every three days from transplanting in each experimental unit. For above-ground attributes, leaf area index (LAI) was measured in 2012, whereas soil coverage ratio was estimated by image processing in 2016. Results showed that [NH4+-N] increased gradually after transplanting and then rapidly decreased from a certain day. This distinct drop in [NH4+-N] informed us the timing at which the rice root system reached the point of porous tubing and thus essentially covered the whole soil volume. The LAI at the dropping point was about 0.43 regardless of the cropping schedules in 2012 experiment. In 2016, the coverage ratio at the N dropping point was within the range of 0.12 to 0.19 for four genotypes having different growth durations. In addition, the coverage ratios at seven weeks after the transplanting showed a good correspondence to LAI across the four genotypes. We therefore conclude that both LAI and coverage ratio may serve as robust indicators for root development and might be useful to estimate the timing when the root system fully cover the soil volume. Results obtained here will also contribute to develop models that can predict not only above-ground canopy development but also associated below-ground processes.

• Journal of Korean Society of Forest Science
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• v.95 no.3
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• pp.309-315
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• 2006

This study was to compare the biomass and annual net production between 60 to 70-year-old Quercus mongolica stand facing northern and southern aspect in Mt. Joongwang (1000 m from sea level), Pyungchang and 35-year-old Q. mongolica stand in Mt. Wolak (300m from sea level), Jechon. The total biomass was 252.9 ton/ha in northern aspect and 212.2 ton/ha in southern aspect of Mt. Joongwang while 198.7 ton/ha in northern aspect of Mt. Wolak. Annual net production was 17.3 ton/ha/yr in northern aspect and 14.2 ton/ha/yr in southern aspect of Mt. Joongwang while 21.2 ton/halyr in Mt. Wolak. Total biomass, especially leaf and branch biomass in north slope was greater than those in south slope of Mt. Joongwang. Leaf area index (LAI) of Q. mongolica stand was 11.17 in Mt. Wolak while 5.77 in northern aspect and 3.97 in southern aspect of Mt. Joongwang, and the net assimilation rate (NAR) was 2.60 kg/kg/yr, 4.26 kg/kg/yr, 6.06 kg/kg/yr in same order.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.4
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• pp.282-290
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• 2013

Biophysical and biochemical processes through which crops interact with the atmosphere have been simulated using land surface models and crop growth models. The Noah Multi Physics (MP) model and the CERES-Rice model, which are a land surface model, and a crop growth model, respectively, were used to simulate and compare rice growth and evapotranspiration (ET) in the areas near Haenam flux tower in Korea. Simulations using these models were performed from 2003 to 2012 during which flux measurements were obtained at the Haenam site. The Noah MP model failed to simulate the pattern of temporal change in leaf area index (LAI) after heading. The simulated aboveground biomass with the Noah MP model was underestimated by about 10% of the actual biomass. The ET simulated with the Noah MP model was as low as 21% of those with the CERES-Rice model. In comparison with actual ET measured at Haenam flux site, the root mean square error (RMSE) of the Noah MP model was 1.8 times larger than that of the CERES-Rice model. The Noah MP model seems to show less reliable simulation of crop growth and ET due to simplified phenology processes and assimilates partitioning compared with the CERES-Rice model. When ET was adjusted by the ratio between leaf biomass simulated using CERES-Rice model and Noah MP model, however, the RMSE of ET was reduced by 30%. This suggests that an improvement of the Noah MP model in representing rice growth in paddy fields would allow more reliable simulation of matter and energy fluxes.

• Korean Journal of Medicinal Crop Science
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• v.6 no.4
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• pp.286-293
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• 1998

This study was carried out to find the effects of seed tuber position and number of nodes on growth of Saururus chinensis Baill. at experimental field of Chungbuk Provincial Rural Development Administration from 1996 to 1997. Seed tubers were divided into upper, middle and lower parts, and they were prepared to 1-, 2-, 3-node cuttings in each. Percentage of sprouting in planting of middle part was highest of 92%, and the percent increased by increasing the number of nodes. Growth of shoot and root tuber was the most favorable with planting of 3-node cuttings of middle part, and leaf area index (LAI) was highest of 3.10 in the same treatment. Dry matter weight and percentage of root tuber were highest of $821g/m^2$ and 28 % with planting of 3-node cuttings of middle part. Yield of dry leaf and root tuber were highest of 272kg/10a and 821kg/10a with planting of 3-node cuttings of middle part.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.4
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• pp.409-416
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• 1987

The object of this study was to investigate the differences in dry matter production, physiological characteristic and grain yield of soybean (Glycine max (L.) Merr.) as affected by planting dates in southern region of Korea. This experiment was conducted using four planting dates and four varieties over 3 years (1982-1984). The different responses of soybean varieties to different temperature and daylength, days from planting to flowering were ranged from 43 to 55 days when planted on May 10 long daylength and low temperature condition. Flowering duration was ranged from 12 to 27 days and 9 to 13 days for the plantings made on May 10 and July 9, respectively. Therefore, it was the shortest under the short daylength and high tempera-ture condition. It also appeared that the later planting caused the lower dry matter weight and leaf area index which resulted in lower grain yield. But grain yield was not directly correlated with the unbalance of Xink/Source Ratio and the lodging from excessive vegatative growth. The grain yield was the highest in May 30 and the lowest in July 9 planting: it was ranged from 2.26 to 2.55 t/ha in the former and 0.85 to 1.20 t/ha in the latter, respectively. The increase in yield was depended on the increase in the number of pods per plant, the number of seeds per pod and the seed weight. The distribution ratio of dry matter to leaves was the hightest at the sixth trifoliolate leaf stage and gradually declined thereafter in all planting dates, and it also appeared that the later planting, the lower the ratio of dry matter to leaves.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.4
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• pp.360-365
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• 1991

This experiment was conducted to determine mechanized seeding ability of barley drill seeder on the seeding time, growth and yield of sorghum-sudangrass hybrid. The time required for machine drill seeding was 42 minutes per l0a which was one-thirteenth of the time required by the manual drill seeding, and percentage of seedling establishment by machine drill seeding was better than that of manual drill seeding. Leaf area index in seeding rate with 30 x 5cm and 40 x 5cm of machine drill seeding was higher than those of manual drill seeding, the leaf distribution was better and the total nonstructural carbohydrate content of stubble after cutting was short increased than that of manual drill seeding, Content of feed composition was not significantly different between manual and machine drill seeding. At seeding rate of 40 x 5cm of machine seeding. dry matter and TDN yield were increased to 29% and 30% respectiyely, than those of manual drill seeding.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.2
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• pp.85-91
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• 2014

Ground-based polarimetric scatterometers have been effective tools to monitor the growth of crop with multi-polarization and frequencies and various incident angles. An important advantage of these systems that can be exploited is temporal observation of a specific crop target. Polarimetric backscatter data at L-, C- and X-bands were acquired every 10 minutes. We analyzed the relationships between L-, C- and X-band signatures, biophysical measurements over the whole corn growth period. The Vertical transmit and Vertical receive polarization (VV) backscattering coefficients for all bands were greater than those of the Horizontal transmit and Horizontal receive polarization (HH) until early-July, and then thereafter HH-polarization was greater than VV-polarization or Horizontal transmit and Vertical receive polarization (HV) until the harvesting stage (Day Of Year, DOY 240). The results of correlation analysis between the backscattering coefficients for all bands and corn growth data showed that L-band HH-polarization (L-HH) was the most suited for monitoring the fresh weight ($r=0.95^{***}$), dry weight ($r=0.95^{***}$), leaf area index ($r=0.86^{**}$), and vegetation water content ($r=0.93^{***}$). Retrieval equations were developed for estimating corn growth parameters using L-HH. The results indicated that L-HH could be used for estimating the vegetation biophysical parameters considered here with high accuracy. Those results can be useful in determining frequency and polarization of satellite Synthetic Aperture Radar stem and in designing a future ground-based microwave system for a long-term monitoring of corn.