• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.1
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• pp.47-55
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• 2020

This study was conducted to evaluate the flowering characteristics of 22 soybean (Glycine max Merrill) varieties of North Korea and classify the flowering group by the flowering date. The flowering date and the days required for flowering with the different planting times on May 31, June 19, June 30, July 3, and July 4 were investigated at the agricultural experimental field of Korea University for three years from 2017 to 2019. The flowering date and the days for flowering of "Yeonpungkong", an early maturing soybean cultivar of Korea, were July 18 and 48 days, respectively, at the planting time of May 31, those of "Daewonkong", a mid-late maturing cultivar, were July 30 and 60 days, respectively. Based on the flowering dates of "Yeonpungkong" and "Daewonkong", North Korean soybean varieties were classified into six flowering groups. Eight North Korean soybean varieties had the flowering dates earlier than "Yeonpungkong", including "Brekkhat" classified into the early flowering group. The range of flowering date was July 2 to 15 at planting time of May 31. Twelve North Korean soybean varieties had flowering dates similar to or later than "Daewonkong", including "Chang Dan Bac Mok" classified into the mid-late flowering group. The range of flowering date was July 24 to 30 at the planting time of May 31. For flowering response to environmental stimulus, all of the mid-late flowering varieties of North Korea responded to "photosensitive or day-length" for flowering reaction. The early flowering varieties were divided by "photosensitive" response and "temperature" response variety.

• Preventive Nutrition and Food Science
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• v.21 no.2
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• pp.97-103
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• 2016

In our previous study, an early-maturing variety of rice (Oryza sativa L.), Jinbu can have feature with unique green color, various phytochemicals as well as nutritive components by the optimal early harvesting, called Green Rice$^{(R)}$ (GR). The aims of the present field experiments were to evaluate the changes in the weight of 1,000 kernels, yield, and contents of proximate and bioactive compounds in Chuchung, a mid-late maturing variety, during the pre-harvest maturation of rough rice and to research the appropriate harvest time and potent bioactivity of Chuchung GR. The weights of 1,000 kernels of Chuchung GR dramatically increased until 27 days after heading (DAH). The yields of Chuchung GR declined after 27 DAH and significantly declined to 0.0% after 45 DAH. The caloric value and total mineral contents were higher in the GR than in the full ripe stage, the brown rice (BR). In the GR, the contents of bioactive compounds, such as ${\gamma}$-aminobutyric acid, ${\gamma}$-oryzanol, and ${\alpha}$-tocopherol, were much higher (P<0.05) than those in the BR, specifically during 24~27 DAH. Therefore, bioactive Chuchung GR can be produced with a reasonable yield at 24~27 DAH and it could be useful for applications in various nutritive and functional food products.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.4
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• pp.404-412
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• 2011

This experiment was conducted to clarify the effect of the temperature for grain filling duration on quality and taste of cooked rice cultivated in different region in Korea. In 2006 and 2007, 4 mid-late maturing group of rice varieties (Nampyeongbyeo, Ilpumbyeo, Junambyeo and Dongjin 1) were cultivated in 28 experimental plots of 27 different regions located in 8 provinces. The taste of cooked rice were positively correlated with 1,000 grain weight but negatively correlated with protein content of brown rice. Mean temperature for 30 days from heading was more closely correlated with grain filling and tastes of cooked rice than those for 40 days. Though, the optimum mean temperature for the best taste of cooked rice for 30 days after heading was 22.1 to $23.1^{\circ}C$ depending on varieties, in general, 1,000 grain weight and cooked rice taste were the highest in the mean temperature of $22.2^{\circ}C$ for 30 days from heading. But grains were poorly ripened in case of the mean temperature lower than $21.0^{\circ}C$ for 30 days after heading. Therefore, for the better taste of cooked rice in Korea, the developing new rice varieties and cultivation method should be focused to adjust the mean temperature within $22-23^{\circ}C$ during the period of 30 days after heading.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.6
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• pp.378-383
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• 2005

This study was conducted in order to exam­ine relationships between the viviparous germination ability and the antioxidative system in rice seeds and seedlings. Enzyme activities was compared among the four varieties with different viviparous germination ability from the early or mid-late maturity group. $\alpha$-Amylase activities correlated with the viviparous germination rate (VGRs) and $\alpha$-amylase activity in seeds of 40 days after heading (DAH) was highest in Dongjinbyeo among mid­late maturing varieties (MLMVs) and in Daeseongbyeo among EMVs. $\alpha$-Amylase activity in dry mature seeds was also higher in varieties with higher VGR. Glucose contents in viviparously germinating seeds and mature dry, seeds were higher in varieties with higher VGRs. Cat-alase activities did not correlate with the VGRs in both maturity groups. However, peroxidase activities in viviparously germinating seeds were higher in varieties with higher VGRs.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.2
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• pp.74-87
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• 2016

Potato phenology, growth, and yield are projected to be highly affected by global warming in the future. The objective of this study was to examine the responses of potato growth and yield to environmental elements like temperature, solar radiation, and daylength. Planting date experiments under open field condition were conducted using three cultivars differing in maturity group (Irish Cobbler and Superior as early; Atlantic as mid-late maturing) at eight different planting dates. In addition, elevated temperature experiment was conducted in four plastic houses controlled to target temperatures of ambient temperature (AT), $AT+1.5^{\circ}C$, $AT+3^{\circ}C$, and $AT+5^{\circ}C$ using cv. Superior. Tuber initiation onset was found to be hastened curve-linearly with increasing temperature, showing optimum temperature around $22-24^{\circ}C$, while delayed by longer photoperiod and lower solar radiation in Superior and Atlantic. In the planting date experiments where the average temperature is near optimal and solar radiation, rainfall, pest, and disease are not limiting factor for tuber yield, the most important determinant was growth duration, which is limited by the beginning of rainy season in summer and frost in the late fall. Yield tended to increase along with delayed tuber initiation. Within the optimum temperature range ($17^{\circ}-22^{\circ}C$), larger diurnal range of temperature increased the tuber yield. In an elevated temperature treatment of $AT+5.0^{\circ}C$, plants failed to form tubers as affected by high temperature, low irradiance, and long daylength. Tuber number at early growth stage was reduced by higher temperature, resulting in the decrease of assimilates allocated to tuber and the reduction of average tuber weight. Stem growth was enhanced by elevated temperature at the expense of tuber growth. Consequently, tuber yield decreased with elevated temperature above ambient and drop to almost nil at $AT+5.0^{\circ}C$.