• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.3
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• pp.214-223
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• 2017

A total of 15 different corn hybrids, Kwangpyeongok, Gangdaok, Yanganok, Singwangok, Jangdaok, Cheonganok, Cheongdaok, Andaok, Dapyeongok, Pyeongkangok, Pyeonganok, Daanok, Sunwon 184, Gangilok, and P3394 was used to investigate the growth and yield depending on the sowing date. The sowing dates were April 5, June 25, and July 5 and each experiments was performed in triplicste. The growth of Gangdaok was the highest. However, although the growth of Kwangpyeongok, was lower thanthar of Gangdaok, its stem height to ear height ratio was lower than that of Gangdaok, thus, Kwangpyeongok may be more suitable for stable cultivation. Both growth and yield of Daanok were low, regardless of planting date, but yield and ear shape of Pyeongkangok and Dapyeongok were for fresh corn. Growth and yield of the 15 different corn hybrids varied depending on the planting date, However, the growth degree days (GDD) was the most important factor governing the maturity of corn. More than $1500^{\circ}C$ of GDD was sufficient to harvest mature corn hybrids in the central region of Korea. Besides yield and growth, other characteristics, such as sweetness and taste of the hybrids, should be investigated further the selection of the best corn hybrid.

• Korean Journal of Medicinal Crop Science
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• v.21 no.5
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• pp.372-379
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• 2013

The present study was investigated the effect of planting density on plant growth and yield of Panax ginseng C. A. Meyer. Sowing density is one of the most important factors affecting yield. The value of roots have affected by shape, color, weight and degree of disease injury in ginseng. Also, it needed to minimize elapsed time for 5 years including pre-planting field management and cultivation period. We were conducted to evaluate that planting densities and varieties on the growth, yield and missing rate. The direct sowing was treated seeds density as a four levels (seeds; 72, 90, 120, 144) and 10 different varieties with 3 years old ginseng roots. Root weight was significantly affected by planting density and variety, but the number of lateral root and yield were affected by only planting density. Growth index was related to variety and planting density. Also, Root shape index was affected by both varieties and planting densities. Suitable planting density and variety were 120 plant per 1.62 $m^2$ and Gopoong, respectively. Results showed that it was also a significant difference (p=5%) in variety of planting density on growth.

• Proceedings of the Korean Society of Crop Science Conference
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• 2019.04a
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• pp.9-9
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• 2019

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.531-540
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• 2016

The adoption of legume cover crops in no-tillage system can contribute to improve soil fertility by providing several benefits, including reduction in soil erosion, suppression of weed growth and N supply to subsequent crops. We conducted a field study to investigate the effect of cover crops and nitrogen fertilization rates on yield and nitrogen use efficiency of waxy corn (Zea mays L.) in no-tillage upland field. Two legume cover crops, hairy vetch (Vicia villosa Roth) and crimson clover (Trifolium incarnuturn L.) were mechanically terminated with roller in early June. For each cover crop treatment, nitrogen (N) fertilizer was applied at three different rates (145, 72.5 and $0kg\;N\;ha^{-1}$). The growth and yield characteristics of corn were significantly affected by the N fertilization rates in crimson clover plots, which suggest N mineralization from the cover crop residue was not sufficient. In contrast, N fertilization rates had no significant effect on growth and yield of corn in hairy vetch plots, indicating that the amount of N released from the cover crop is large enough to meet most of the N requirement of corn. However, the application of N fertilizer in hairy vetch cover plots resulted in slight increase of crop yield, though not statically significant, and high levels of N concentration in corn plant tissue possibly due to luxury consumption of N. Organic residues on the soil surface in hairy vetch cover plots had substantial amounts of N after harvest, ranging from 100 to $116kg\;N\;ha^{-1}$, which is presumably retained during winter season and released by microbial mineralization in subsequent year. The highest nitrogen yield efficiency was achieved in the plot with hairy vetch cover and no N fertilizer application, followed by the plot with hairy vetch cover and $72.5kg\;N\;ha^{-1}$ fertilization rate. In conclusion, hairy vetch showed better performance in corn productivity as compared with crimson clover. In addition, it was concluded that the application of N fertilizer between 0 and $72.5kg\;N\;ha^{-1}$ in combination with hairy vetch cover crop might be most efficient for corn yield under no-tillage system with climatic and soil characteristics similar to those of the experimental site.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.1
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• pp.15-19
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• 2013

This study was carried out to establish the optimum organic fertilization and microbial compost on wheat cultivation in order to reduce the use of chemical fertilizers and improve the quality of wheat. The tests resulted in a yield of organic fertilization of 2~6% lower than the yield of standard 4.16 Ton/ha (a yield more than that of microbial compost). The recession was not statistically significant. The trial which involved organic fertilizer that had a yield of 800 kg/ha and microbial compost which had a yield of 2,000 kg/ha resulted in 96% yield of standard trial. The quality of flour in the manure was 50% less during the trial and was not making a good result. In protein content and SDS-sedimentation volume, standard trial had the highest yield in test trial (standard > miccompost > organic fertilization). However, Ash content was not statistically significant.

• Korean Journal of Agricultural Science
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• v.49 no.3
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• pp.421-430
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• 2022

Crop load management in apple trees is important for achieving optimum productivity and crop value. Hence, we investigated the influence of different crop loads on the fruit quality, mineral content, and yield of the 'RubyS' apple variety. After 4 weeks of full bloom, the crop load was adjusted by hand thinning to different (5, 10, and 15 fruits·cm^-2) trunk cross-sectional areas (TCSA), representing low, medium, and high crop loads. The low crop load increased the fruit size and weight, the development of the red-blushed area, and the peel color a^* at harvest; however, it reduced the total number of fruits·tree^-1 and yield compared with that of the other crop loads. The medium crop load improved the fruit weight, flesh firmness, and soluble solids content and reduced the fruits·tree^-1 but did not affect the fruit size and yield. However, there were no significant differences in the titratable acidity and starch index among the crop loads. The fruit mineral content (phosphorus and potassium) was higher in the low and medium crop loads compared to the high crop load. However, the nitrogen, calcium, and magnesium contents in the fruits were not affected by the crop loads. Overall, this study suggests that a low crop load improves the fruit size and weight, but its effect on the quality and fruit mineral content is similar to that of a medium crop load. Therefore, the optimum crop load level for the 'RubyS' apple trees was approximately 10 fruits·cm^-2 TCSA.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.318-318
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• 2017

This study was conducted to find optimum mixed sowing ratio of green manure crops to reduce the use of chemical fertilizer as well as to increase the crop yield potential which will foster the utilization of green manure crops in the upland field in view of environment friendly agriculture. According to the study, the mixed ratio, 50:50, of hairy vetch and green barley showed highest nitrogen production yield in the soil due to the relatively higher organic nitrogen supply from the hairy vetch plant as well as nitrogen fixation from the air rather than other mixed ratio. In the 50:50 mixed ratio of hairy vetch and green barely total nitrogen amount in the soil showed 17.2kg per 10a, but in the other treatment ratio such as 75:25, 25:75. total nitrogen fixation amount were 16.7, 16.9 respectively. We also conducted the experiment to compare the effect of the mixed sowing treatment of green manure crops on the production of corn cultivated as a succeeding plant of hairy vetch. According to the result, the mixed ratio, 50:50, of hairy vetch and green barley treatment showed highest yield potential of corn as 153kg per 10a in seed weight which is due to the relatively higher organic nitrogen supply from the hairy vetch plant as well as nitrogen fixation from the air rather than other mixed ratio. In the mixed sowing treatment of hairy vetch 100 and barley 0 ratio, the corn production showed 148kg per 10a which is 5kg lower than that of hairy vetch 50 and barley 50 ratio, but showed statistically no difference between those two treatment. Otherwise, different treatments, such as hairy vetch 75 and barley 25, 25 and 75, 0 and 100 showed statistically different each other. Therefore, it was concluded that green manure crops, such as hairy vetch, green barley and rye were very effective crops to increase the soil fertility and gave the positive effect to the crops to give vegetative and propagative growth condition and, in turn, increased the yield potential. We have to make policy to enhance the utility of green manure crops in the upland crops as well as faddy field for the soil fertility and crop yield production which will guarantee prominent quality of environment friendly agriculture products.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.4
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• pp.458-463
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• 2015

This study was conducted to investigate the mixed seeding of 5 forage barley varieties (youngyang, yuyeon, dami, wooho, soman) with 1 malting barley variety (hopum). Yield of the mixed seeding was compared with each single seeding and variety combinations. Yield of mixed seeding combination was higher than each single seeding. In mixed seeding of 'Youngyang' and 'Hopum' (50% and 50% ratio), 'Yuyeon' and 'Hopum' (70% and 30% ratio), 'Dami' and 'Hopum' (50% and 50% ratio), 'Wooho' and 'Hopum' (50% and 50% ratio) were higher yield of dry weight than yield of other mixed ratios. Most of all, mixed seeding of 'Dami' and 'Hopum' were high yield mixed seeding (ratios of 50% each other). In generally, the yields of barley mixed seeding with malting barley 'Hopum' were high production. The forage quality of mixed seeding combination was higher than any each single seeding. 'Youyeon' 50% and 'Hopum' 50% ratio was more higher TDN content (69.2%) than any other mixed combination.

• Korean Journal of Plant Resources
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• v.19 no.6
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• pp.697-699
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• 2006

To find out the best complex fertilizer for high yielding of rapeseed crop, experiment was conducted on complex fertilizers at the experiment field in upland of rapeseed in Mokpo Experiment Station, Nat'l Institute of Corp Science, RDA, Korea. Experiment was laid out in randomized complete block (RCBD) design. The effects of complex fertilizer (22-22-11) on the number of branches, pod length, percentage of seed set and seed yield were highest but on the plant height, ear length, and number of pods per ear were negligible. On th basis of the results reported above, for getting higher yield of rapeseed crop, among the tested fertilizers complex fertilizer (22-22-11) gave the superior performance and is recommended for application.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.4
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• pp.277-283
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• 2018

The crop growth model has been widely used for climate change impact assessment. Crop growth model require genetic coefficients for simulating growth and yield. In order to determine the genetic coefficients, regional growth monitoring data or yield trial data of crops has been used to calibrate crop growth model. The aim of this study is to verify that yield trial data of corn is appropriate to calibrate genetic coefficients of CERES-MAIZE. Field experiment sites were Suwon, Jinju, Daegu and Changwon. The distance from the weather station to the experimental field were from 1.3km to 27km. Genetic coefficients calibrated by yield trial data showed good performance in silking day. The genetic coefficients associated with silking are determined only by temperature. In CERES-MAIZE model, precipitation or irrigation does not have a significant effect on phenology related genetic coefficients. Although the effective distance of the temperature could vary depending on the terrain, reliable genetic coefficients were obtained in this study even when a weather observation site was within a maximum of 27 km. Therefore, it is possible to estimate the genetic coefficients by yield trial data in study area. However, the yield-related genetic coefficients did not show good results. These results were caused by simulating the water stress without accurate information on irrigation or rainfall. The yield trial reports have not had accurate information on irrigation timing and volume. In order to obtain significant precipitation data, the distance between experimental field and weather station should be closer to that of the temperature measurement. However, the experimental fields in this study was not close enough to the weather station. Therefore, When determining the genetic coefficients of regional corn yield trial data, it may be appropriate to calibrate only genetic coefficients related to phenology.