• Journal of Bio-Environment Control
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• v.23 no.3
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• pp.167-173
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• 2014

This research was conducted to establish appropriate methods to prune tomato side stems during summer. Cherry tomatoes "Unicorn" (Monsanto Korea, Korea) were grown in the coir based growing medium, and irrigation was controlled time based system. There were three pruning treatments: 1) removing all side stems (ACUT), 2) remaining two leaves on the side stems right below any cluster (PCUT), and 3) remaining two leaves on all side stems (LEFT). Experimental results showed that the occurrence of swollen stems, a symptom of nutrient excess, was influenced by side stem pruning due to blocking of consumption of photosynthetic products. The photosynthetic rate was not different between leaves on main stem and those on side shoots. Therefore the differences in the total amounts of photosynthetic products seemed to come out from the differences in leaf areas on each treatments, influencing on fruit yield difference. The yields and harvesting rates were better in ACUT treatment when tomato plants were harvested until $5^{th}$ cluster, however tomato yield was higher in LEFT treatment when more then $5^{th}$ clusters were harvested.

• Korean Journal of Food Science and Technology
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• v.39 no.3
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• pp.246-254
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• 2007

Fresh tea leaves grown in Jeju Island and Jeonnam Province of South Korea were plucked and processed. Volatile compounds (VCs) were analyzed and identified with SPME-GC/GC-MS/GC-O. The VCs of green teas were classified into two major categories based on their aroma characteristics: the Greenish (Group I), and Floral (Group II) odorants. It was found that the VCs were decreased significantly in fresh tea leaves as they were plucked at the later stages of cultivation. The ratio of VCs responsible for Group I and Group II compounds was well-balanced in tea leaves plucked in May, but the balances were changed when the fresh leaves were processed. The major VCs of fresh tea leaves in Jeju and Jeonnam were n-hexanal, E-2-hexenal, Z-3-hexenal, myrcene, benzyl alcohol, linalool, and phenyl alcohol. Also, Jeju and Jeonnam tea leaves had different aroma composition. n-Heptanol, ${\beta}-pinene$, benzaldehyde, and ethyl salicylate were found in Jeju fresh tea leaves, and Z-3-hexenol, E-2-hexenol, and methyl n-heptanoate were detected in Jeju dry tea leaves. On the other hand, Z-linalool oxide and myrcene were found in Jeonnam dry tea leaves. The SPME-GC method showed high reproducibility (RSD, 7.4%) with no-artifact formation. In this study, optimum plucking period of tea leaves could be determined for production of high quality green tea with a well-balanced aroma and characteristic VCs in green tea according to growing areas.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.3
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• pp.167-171
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• 2009

An attempt was made to provide the most reasonable fertilizer recommendation for radish crop based on soil analysis data and yield response to the N, P, K fertilizers, which was obtained from field experiments on 2004 in highland, 850 meters above the sea level. Optimum times of NPK application to past application amount based on soil test were 0.90-0.77-0.50 for radish. The adjusted NPK recommendation models of highland soil were made by adding the application times to past application methods which were based on chemical properties of soil. The revised models for fertilizer application were recommended to decrease the amount of N, P, K by 10-23-50% for radish in highland. In application to total cultivation area, 2,546ha for radish, saving amounts of NPK fertilizers with these adjusted recommendation in comparison with past application levels will be 244.4 tons for radish. Using the optimal application amounts for radish, we will can reduce agricultural pollution without affecting crop yields.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.260-260
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• 2011

SWAT is semi-distributed and continuous-time distributed simulation watershed model, which can simulate point and nonpoint source pollutants as well as hydrology and water quality. It was developed to predict the effects of alternative management decisions on water, sediment, and chemical yields with reasonable accuracy. It is able to predict and manage hydrology, sediments, nutrients, and pesticides with Best Management Practices (BMPs) in a watershed. SWAT model also has potential for use in ungauged basins to predict streamflow and baseflow from saturated source area in watersheds. According to various cultivation practices and climate change, SWAT model is available to analyze relative change in hydrology and water quality. In order to establish optimum management of water quality, both monitering and modeling have been conducted actively using SWAT model. As SWAT model is computer program to simulate a lot of natural phenomena, it has limitation to predict and reflect them with on hundred percent accuracy. Thus, it is possible to analyze the effect of BMPs in the watershed where users want to simulate hydrology and water quality only if model accuracy and applicability are assessed first of all and the result of it is well for the study watershed. For assessment of SWAT applicability, most researchers have used $R^2$ and Nash and Sutcliffe Efficiency (NSE). $R^2$ and NSE are likely to show different results according to a warm up period and sometimes its results are very different. There have been hardly any studies of whether warm up period can affect simulation results in SWAT model. In this study, how warm up period has a effect on SWAT results was analyzed and a appropriate warm up period was suggested. Lots of SWAT results were compared after using measured data of Soyanggang-dam watershed and applying various warm up period (0 ~ 10 year(s)). As a result of this study, when there was no warm up period, $R^2$ and NSE were 0.645, 0.602 respectively, when warm up period was 2 years, $R^2$ and NSE were 0.648, 0.632, and when warm up period was 4 years, $R^2$ and NSE were 0.663, 0.652 separately. Through this study, sensitive analysis of warm up period in SWAT model was conducted, and this study could give a guideline able to simulate hydrology and water quality for more accuracy than before as users change a lot of warm up periods as well as any simulation parameters.

• Food Science and Preservation
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• v.9 no.4
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• pp.357-361
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• 2002

This study was carried out to understand the problems, and find out the solution of post - Harvest related procedures for barley in Korea. Consecutive post - harvest procedures in harvesting, drying, milling, packaging and marketing methods were collaborately surveyed at Bujeok (Chungchongnamdo) and Kunsuh (Cholanamdo) agricultural cooperative federation where Chalssalbori (waxy barley) and Ssalbori (non waxy barley) were collectively cultivated in a group farming area, respectively. An early harvesting and relatively short harvesting period within 15 to 20 days to transplanting rice plants as a succeeding crop lead to produce undergrade barley and 2 to 3％ harvesting loss were considered as the problem that should be improved. In drying of barley, wide moisture content range of harvested barley among the different farmers and cultivation land was made difficult barley drying unifomly when they were dried in same dryer and drying temperature was slightely higher with 50 to 70$\^{C}$ than that of optimum temperature (under 50$\^{C}$) fer barley drying for producing the high quality barley. Dried barley packaged in ton-bag or 3P bag and put into the rectangular grain bin were stored in ambient temperature warehouse and milled for marketing through whole you. The physico-chemical properties and taste of stored barley were fairly maintained until May next year.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1137-1143
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• 2011

Optimum soil management of chestnut orchards is important to ensure high quality and yields of chestnut. This study was conducted to evaluate soil and green leaf characteristics by establishment periods of chestnut (Castanea crenata Sieb. et. Zucc.) orchards in Sancheong-gun, Gyeongsangnam-do. Total 30 plots with the criteria of similar cultivation practices were chosen and classified into two establishment periods by over 20-year-old orchards (17 plots) and below 19-year-old orchards (13 plots). Soil bulk density was significantly higher (p<0.05) in over 20-year-old ($1.16g\;cm^{-3}$) than in below 19-year-old ($1.03g\;cm^{-3}$) plots. Soils in over 20-year-old plots were severely acidified with pH 4.56 compared to pH 4.73 in below 19-year-old plots. However, soil organic matter, total nitrogen, available phosphorus, and potassium were not significantly different (p>0.05) between both establishment periods. Leaf area, leaf mass, and nutrient (N, P, K, Ca, Mg) concentration of green leaves were also not significantly different (p>0.05) between both establishment periods. The results indicate that soil bulk density in chestnut orchards is dependent on the establishment periods, while soil chemical property and leaf nutrient concentration may be little influenced by the establishment periods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.360-366
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• 2021

Garlic is an important crop, accounting for 1.1 trillion won out of 3.7 trillion won for the total production of seasoned vegetables in Korea. On the other hand, the cultivation area and production volume are decreasing continuously due to the shortage of an agricultural labor force, aging, and insufficient mechanization. In particular, the mechanization of garlic sowing is barely performed, resulting in large amounts of labor. Therefore, it is necessary to study the mechanization of planting garlic. Therefore, in this study, to determine the optimal working conditions for mechanical sowing of garlic, an experiment was conducted to compare the yield according to the sowing angle and depth of garlic during sowing. After sowing using a seeding machine set under optimal conditions, the conventional work and yield were compared. The results showed that it is most appropriate to sow garlic with a sowing angle of 45° or 90° and a depth of 2 cm to 4 cm, and there is no difference in the yield between sowing with a sowing machine and conventional work.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.2
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• pp.63-69
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• 2019

Black-colored rice contains anthocyanin, which has an antioxidant function on the seed coat. Anthocyanin content is greatly affected by the cultivation environment, especially the average temperature during the ripening stage. Generally, low temperatures during the ripening stage increase anthocyanin content. To control the average temperature during ripening stage in the field, transplanting time has to be regulated. In this study, anthocyanin content variation was examined in relation to the transplanting time and the average temperature during the ripening stage. For the study, fourteen black-colored rice cultivars with different maturity types (four of early-maturing, five of medium-maturing, and five of medium-late maturing) were selected. The transplanting times used were May 20, June 5, June 20, and June 30. The field experiment was conducted in the Miryang, Kyoungsangnamdo province, Korea from 2014 to 2017. The anthocyanin content in all cultivars was higher when the transplanting time was delayed, and the highest anthocyanin content was observed in the transplanting on June 30. Variation in anthocyanin content according to the change in transplanting time is the greatest in the early maturing cultivars. The least change was observed in medium maturing cultivars. Regression analysis showed a significant correlation between temperature and anthocyanin content, but the degree of correlation was very low in the medium maturing cultivar. As a result, the optimal average temperature during the grain filling stage for increasing the anthocyanin content of black colored rice was $22{\sim}23^{\circ}C$. The rice yield increased in plants transplanted until June 20 and decreased thereafter owing to low temperature during the grain filling stage. The anthocyanin content increased with delaying the transplanting time up to June 30 but the rice yield decreased after June 20. Nevertheless, the rate of increase in anthocyanin content was higher than the rate of decrease in rice yield. As a result, the optimum transplanting time and an average temperature of grain filling stage for black-colored rice variety were June 30 and $23{\sim}24^{\circ}C$ considering both anthocyanin content and rice yield.

• Journal of Environmental Science International
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• v.31 no.5
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• pp.413-422
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• 2022

To identify rice (Oryza sativa L.) cultivars suitable for Italian ryegrass (Lolium multiflorum Lam.)-rice double cropping systems, we investigated the yield and grain quality of four different midseason maturing rice cultivars ('Daebo', 'Haepum', 'Haiami', and 'Samdeog') and four midseason-to-late maturing rice cultivars ('Hyunpoom', 'Saeilmi', 'Saenuri', and 'Samkwang') in single rice cropping and Italian ryegrass-rice double cropping systems in paddy fields of Miryang, South Korea. We found that organic matter and available P₂O₅ content slightly decreased, whereas Na content increased, in the soil where Italian ryegrass was cultivated during winter compared to that in the soil that remained fallow during winter. The pH, electrical conductivity, organic matter, and contents of K⁺, Ca²⁺, Mg²⁺, and Na⁺ decreased, whereas the available P₂O₅ content slightly increased, in the soil where rice was harvested in both single and double cropping systems. However, compared to the optimum soil conditions for rice cultivation, available P₂O₅ and K⁺ content were high and Mg²⁺ content was low in both single and double cropping systems. At the heading stage, the culm length and leaf color slightly increased in most of the rice cultivars, whereas the panicle length and number slightly decreased, in the double cropped system. After harvesting, spikelet number and milled rice yield did not show a significant difference between single and double cropping systems. However, the ripened grain rate and weight per thousand grains increased slightly in the 'Saeilmi' and 'Samkwang' cultivars but remained either stable or slightly low in other cultivars in the double cropping system. The milled rice yield was high (> 500 kg/10a) in 'Daebo' and 'Haepum' among midseason maturing rice cultivars, and in 'Saeilmi' and 'Saenuri' among midseason-to-late maturing rice cultivars, in both single and double cropping systems. The head rice rate was high in midseason maturing rice cultivars in the double cropping systems, reaching > 70% in 'Haepum' and 'Haiami' cultivars, whereas it decreased in most midseason-to-late maturing rice cultivars (excluding 'Samkwang' cultivar), in double cropping systems. Particularly, it exceeded > 70% in the 'Saenuri' cultivar in both single and double cropping systems. The protein content in milled rice increased, whereas the amylose content either remained stable or slightly increased, in double cropping systems. The Toyo taste value decreased in all midseason-to-late maturing rice cultivars and slightly increased in the 'Daebo' and 'Haiami' cultivars among midseason maturing rice cultivars in double cropping systems. However, Toyo taste values in the 'Haepum', 'Haiami', and 'Saenuri' cultivars exceeding > 80% in both single and double cropping systems. Therefore, we recommend 'Haepum', 'Haiami', and 'Saenuri' cultivars as candidates for Italian ryegrass-rice double cropping systems due to high yield, head rice rate, and Toyo taste value.

• Korean Journal of Organic Agriculture
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• v.26 no.3
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• pp.439-452
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• 2018

This study was carried out to establish of environment-friendly control system and to survey the occurrence status of Ricania shanthungensis in Jeonnam province from 2016 to 2017. R. shanthungensis occurred at 1,344 ha in 61 towns of 15 cities in Gwangju and Jeonnam province. At four sites in the stationary area, the densities of eggmass and pupae were lower in 2017 than in 2016, the hatching rate decreased, and the first hatching time, emergence of adults, and the start of spawning tended to be slower. Telenomus sp., an egg parasitoid of R. shanthungensis, was found in most areas. Sunchon had the highest rate of 46.1%, followed by Muan 40.6, Goksung 29.2, Gurye 25.8, and Gwangju 17, respectively. The optimum spraying time for the control of R. shanthungensis was early March. The spraying material and the dilution multiples are 10 times of the machine oil at environmental friendly cultivation and 500 times of the chlorpriphosphate wp. at normal cultivation. When sprayed these materials, 95% of egg prohibited to hatch. There was more than 80% of the insecticidal effects on the organic materials of the machine oil emulsion, the Sophora root extrect + microbial extract agent, and the castor emulsion. For adults, Sophora root extrect + microbial extract, neem extract, and machine oil were better. Four kinds of chemical pesticides such as dinotefuran wp were effective for nymph and adult control. We have developed an adult catching device using the most preferred daylight color and behavioral habits of R. shanthungensis. The capture device consisted of two daylight compact lamps (30W and 20W), a yellow plate, and a catcher using water, and caught about 700 individuals a day. Based on the above results, we have established a system for controlling and life cycle of R. shanthungensis in Jeonnam province.