• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.4
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• pp.424-429
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• 2012

This study was carried out to investigate the influence of different planting time on the synthesis of isoflavone in black soybean, Three varieties used in this experiment were lpumgeomjeongkong, Cheongjakong and Heugcheongkong which had different ecotypes, repectively. Seeds were sown at different time, May 15th, May 30th and June 15th with planting density of $60{\times}15cm$. In order to analyze the content of isoflavone, we collected sample every 5 days from 30 days after flowering to harvest and analyzed them with UPLC. As sowing was delayed, the content of isoflavone increased in all of three varieties. The content of genistein was greater than daidzein and glycitein. Increase of Glycitein was not distinct from 55 days after flowering(DAF) and it was stable against temperature change during the seed developing period. Although the content of genistein in Ilpumgeomjeongkong from 50 to 55 DAF, in Cheongjakong from 40 to 55 DAF and in Heugcheongkong from 60 to 65 DAF was lower than the content of daidzein, it was higher than that of daidzein afterward. In the statistical analysis on the relationship between average temperature and the content of aglycone isoflavone at 5-day intervals from 30 DAF during the grain filling period, genistein in Ilpumgeomjeongkong showed meaningful correlation as y=-15.28x+407.9 ($R^2=0.505^*$), diadzein in Cheongjakong showed meaningful correlation as y=-6.188x-164.5($R^2=0.454^*$), and genistein showed significantly high correlation as y=-11.59x+297.6 ($R^2=0.545^{**}$). Taking all the above results into consideration, it was suggested that the regions suitable for high content of isoflavone in black soybean be the northern area of Gyeonggi-do and Gangwon-do, Chungcheongbuk-do and inland area of Gyeongsangbuk-do, where are relatively low average temperature from flowering stage($R_2$) during the grain filling period.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.1
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• pp.93-103
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• 1992

Experiments were conducted in the research field of the Wheat and Barley Research Institute with three barley cultivars, Olbori, Kangbori and Suwon 18, which showed different growth characteristics. The highest rates of daily dry matter accumulation in grains were 1.03 1.94 mg / grain / day in early and optimum sowings and 0.88 1.88 mg / grain / day in late sowings, which occurred around 20～30 days after heading in early and optimum sowings and 15～20 days after heading in late sowings. Grains reached their maximum weight by 40 days after heading in early and optimum sowings and 35 days after heading in late sowings. Total sugar content in grains followed a pattern of linear increase immediately after heading, but it started to decrease around 20 days after heading. On the other hand, starch content continued to increase until maturity. The contents of both components were high in the order of ＆apos;Olbori＆apos; ＆gt; ＆apos;Kangbori＆apos; ＆gt; ＆apos;Suwon 18＆apos;, but they did not respond in a regular pattern to different sowings. 1,000 grain weight showed highly significant positive correlation(r=0.767$^{**}$) with the duration of grain growth, but it had negative correlations with the average (r=-0.548$^{**}$) or the sum (r=-0.595$^{**}$) of post-anthesis daily mean temperature.ature.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.386-393
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• 1984

This study was carried out to identify the ecological characters easily changeable with the conditions of temperature and day-length and to ascertain the managable means which can optimize the barley plants to secure the maximae yield and early heading under controlled condition. Yield and yield components were greatly varied with temperature. Especially, effective tiller formation and grain filling of sub-tillers were more favorably affected by thermal treatment than those of main tiller. In thermic response, 'Kangbori' was less susceptible than others, while 'Sacheon #6' showed particular susceptability. The varietal differences of photoperiodic response were recognized on all investigated traits and their degree of response were similar to those with temperature. Among varieties, 'Kangbori' was comparably sensitive on several characters while 'Sacheon #6' displaying low light-sensitivity. The turning point at which heading might be radically stimulated was estimated as about 10.5 hour day-length in 3 tested varieties and above 18 hours of irradiance was considered ineffective for more rapid heading. The condition under which barley varieties may obtain maximal yield and resonably early heading was 15$^{\circ}C$ in temperature and 12 to 15 hours of day-length, regardless of varieties. of day-length, regardless of varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.s02
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• pp.34-44
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• 1989

The stability of rice cultivation in Korea is largely depended on climatic conditions, especially, low temperature at the period of early growth stage and after heading. The improvement of cold tolerant varieties and appropriate cultural practices in rice are very effective to minimize the cold damage. This paper is summarized the mechanism and counterplans of cold injury of rice plants. The paddy area having commonly cold injury in Korea is approximately 15, 522ha in 1,709 sites on the national scale. The cold damage at seedling stage in nursery bed appeared to poor germination, leaf discoloration, dead seedlings and seedling rot ect.. At the vegetative stage, the decreased tiller number due to poor rooting and the delayed heading caused by slow growth and panicle differentiation are commonly showed. The cold injury at early reproductive stage appeared to the degeneration of spikelets and rachis - branches, while that at meiosis stage showed to increased sterility due to poor development of pollen and shortened panicle length with delaying heading, therefore the grain yield is largely decreased. The cold damage at heading and ripening stages showed to poor pollination and fertilization, low panicle exsertion, poor grain filling and finally grain quality became low. To minimize the cold injury to rice plants by low temperature, following counterplans would be recommonded ; Improvement of the cold toelrant rice varieties for the regions of midmountains and alpines. Raising healthy seedlings at upland nursery beds and by using of growth regulators such as ABA, Fuchiwang and Tachiace. Soil improvement and organic matter application to reduce cold damage by increasing water and fertilizer holding capacities in the paddy field having commonly cold water and in the place where cold damage is regularly occurred. Appropriate fertilization for raising healthy rice plants to tolerate under low temperature condition. Water management to increase water temperature in the paddy such as depth watering, round channels and polyethylene tubes around the field. Establishment of the optimum cultivation time of rice based on minimum, mean and maximum temperatures at different regions with appropriate rice varieties.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.346-358
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• 2023

Due to the acceleration of climate change or global warming, it is important to predict rice productivity in the future and investigate physiological changes in rice plants. The research aimed to explore how rice adapts to climate change by examining the response of nitrogen absorption and nitrogen use efficiency in rice under elevated levels of carbon dioxide and temperature, utilizing the SPAR system for analysis. The temperature increased by +4.7 ℃ in comparison to the period from 2001 to 2010, while the carbon dioxide concentration was held steady at 800 ppm, aligning with South Korea's late 21st-century RCP8.5 scenario. Nitrogen was applied as fertilizer at rates of 0, 9, and 18 kg 10a^-1, respectively. Under conditions of climate change, there was an 81% increase in the number of panicles compared to the present situation. However, grain weight decreased by 38% as a result of reduction in the grain filling rate. BNUE, indicative of the nitrogen use efficiency in plant biomass, exhibited a high value under climate change conditions. However, both NUEg and ANUE, associated with grain production, experienced a notable and significant decrease. In comparison to the current conditions, nitrogen uptake in leaves and stems increased by 100% and 151%, respectively. However, there was a 25% decrease in nitrogen uptake in the panicle. Likewise, the nitrogen content and NDFF (Nitrogen Derived from Fertilizer) in the sink organs, namely leaves and roots, were elevated in comparison to current levels. Therefore, it is imperative to ensure resources by mitigating the decrease in ripening rates under climate change conditions. Moreover, there seems to be a requirement for follow-up research to enhance the flow of photosynthetic products under climate change conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.3
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• pp.189-197
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• 2022

This study investigated the antioxidant and yield properties of eight adzuki bean (Vigna angularis L.) cultivars grown under different mean temperatures and sunshine hours in 2020 and 2021. Compared to 2021, which had a normal mean temperature, 2020 showed a lower mean temperature during the pod-extension and grain-filling periods. In addition, due to frequent rainfall during the vegetative period in 2020, there were fewer hours of sunshine in 2020 than in 2021. The adzuki bean yield was approximately 13% lower in 2020 than in 2021 due to the decreased number of pods per plant and 100-seeds weight. 'Hongda' and 'Hongjin' cultivars showed more stable yields than the 'Arari' variety, which is the most commonly cultivated variety in Korea. Moreover, the 'Hongda' and 'Hongjin' cultivars had higher yields than the 'Arari' variety in both years. Compared to 2021, in 2020, when the weather conditions were unfavorable, both antioxidant levels and activity were higher. 'Hongda' had higher antioxidant levels and activity than the other cultivars over the 2 years. These results suggest that the antioxidant levels and activity were good in 2020, with an approximately 13% decrease in yield compared to 2021, which was a normal year with respect to mean temperature and sunshine hours.

• Journal of Biosystems Engineering
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• v.5 no.1
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• pp.33-42
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• 1980

This study was carried out to investigate the actual environmental paddy storage conditions in conventional Korean farm warehouses. The paddy storage conditions by the locations and sizes of warehouses were figured out. The effectiveness of the small insulated box for storing paddy was also examined. Observations were made at sixteen different warehouses located in Moonsan-Myeon, Jinyandg-gun, Gyungnam Province from July lst to September 28 th, the period which was considered to be the worst for storing grains. The results are as follows ; 1. the average temperatures of rough rice and air inside the warehouse were 0.9 and 0.7$^\circ$ higher than the outside air temperature. 2. The average relative humidity in warehouses was 1.5percent higher than that of the atomosphere. This fact resulted in the increased moisture content of grains. Therefore, the ventilation for equalizing the relative humidity of inside and outside of warehouses was required. 3. The dry matter of stored rough rice was decreased by 1.1 percent in average druing the observation period. In order to reduce the dry matter loss, application of new grain storing method ;hermetic storage or filling inert gas storage, was highly recommended. 4. Environmental conditions for storing rough rice in a warehouse located in a sloping site are, in general , better than those of a warehouse located in a flat site. But as far as the dry matter of rough rice was concerned, above situation is not always satisfactory. Because it is fairly frequent to observe the higher rate of moisture absorption by grains stored in a warehouse located in a sloping site. 5. Environmental conditions for storing rough rice in a large-scale warehouse were better than those in a small size warehouse. Therefore, it is advisible for farmers to store their grins in the large-scale warehouses commonly used by villagers. 6. It was undesirable to store rough in a insulated box.

• Journal of Biosystems Engineering
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• v.23 no.3
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• pp.229-244
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• 1998

This study was performed to determine proper fan and heater management schemes for natural air drying of rough rice in round steel bin with stirring device under Korean weather conditions. A computer simulation model was developed to predict moisture content changes, energy requirements, and drymatter losses during drying of rough rice by natural air. Drying test was conducted to validate the simulation model using round steel bin of holding capacity of 300ton at Rice Processing Complex in Jincheon. The bin was filled with rough rice every day and mixing by stirring device. Moisture contents, ambient air temperatures, relative humidities, static pressures in plenum chamber in the bin, airflow rates, and electrical and fuel energy were measured. Relative errors of moisture content changes predicted by the simulation model were below 5ft, and relative errors of final moisture content, final grain weight, required energy ranged from 0.9% to 6%. These not levels indicated that the simulation model can satisfactorily predict the performance factors of natural air drying system such as drying rates and energr consumptions comparing error level of 10% to 15% in other drying simulation models generally used in dryer desists. Twelve different fan and heater management schemes were evaluated using the computer simulation model based on three hourly weather data from Suweon for the period of 1952-1994. The best management schemes were selected comparing the drymatter losses, required drying times, required energy consumptions. Operating fan without heating only when ambient relative humidity was below 85% or 90% appeared to be the most effective method of In operation in favorable drying weather. Under adverse drying climates or to reduce required drying time, operating fan continuously, and heating air with $1.5^{\circ}C$ temperature rise only when ambient relative humidity was over 85% appeared to be the most suitable method.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.165-175
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• 2019

In response to elevated temperature, a shift in the rice planting period was proposed as a promising option in temperate regions. To understand the yield response of early maturing rice to different transplanting dates and to analyze the related agronomic traits in the central plain area, we performed a two-year study using different transplanting dates and six varieties in Suwon, Korea. The maximum head rice weight was achieved in the treatments transplanted between June 14 and 29, depending upon the varieties. The optimal mean temperature during the 40 days from heading stage for attaining the maximum head rice weight was $21.8^{\circ}C$ on the average of six varieties. The index of head rice weight was positively correlated with the indices of both the milled rice weight and head rice percentage, the latter showing a higher coefficient of determination. The highest milled rice weight was commonly achieved from the treatment transplanted on June 29, where the head rice weight was also the highest. The index of milled rice weight was significantly correlated with the indices of grain filling percentage and number of spikelets per area, but not correlated with the index of 1000-brown rice weight. The transplanting date with the highest milled rice yield produced the largest number of spikelets per area, greatest biomass at the heading and harvesting stages, and highest level of harvest index. We suggest that the optimal transplanting date for early maturing rice varieties in the central plain area is from June 14 to 29. High head rice yield in this study was attributed to increased spikelets owing to the increased biomass production at the heading stage, enhanced grain filling due to the high biomass production and harvest index at maturity, and improved head rice percentage.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.353-353
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• 2017

Rice yield of South Korea in 2015 was the highest of the last 30 years. It is important issue to establish food policy whether the historically highest yield in 2015 can be continued or just one-off event. Therefore, it is necessary to understand whether such a high yield as 2015 will be reoccurred. The aim of this study was to find out what climatic factor affect rice yield and how often these climatic factor could occur. For this study, the yield monitoring data from National Institute of Crop Science, Rural Development Administration and the meteorological data provided by Korea Meteorological Administration are used to identify the weather conditions could cause high yield, and how often these conditions occurred in the past. Our results indicated that such as high yield as 2015 could occur only when the mean sunshine hours of July and the mean sunshine hours from the end of August to early September was more than 5.1 hours and 6 hours, respectively. Mean sunshine hour of July may be related to grain number. The mean sunshine hour from the end of August to early September was presumed to relate to grain filling ratio. The relationship between monthly mean temperature and yield or yield component was not clear in this study. In this study, any cycle of high weather condition was not found. Therefore, the probability of high yield weather condition was expressed by frequency. The frequency of the sunshine hour, could make high yield, were 8/35 (23%) over the past 35 years. And the frequency of two years consecutive sunshine hour condition, which could cause high yield, was 1/35 (2.9%). The frequency of recurrence of sunshine hour making high yield within the next 5 years or 10 years after high yield weather condition were 4/35 (11.4%). After all, the high yield as much as yield of 2015 could not be one-off event. But it was not also consecutive event.