• 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.45 no.6
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• pp.356-360
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• 2000

With isogenic waxy and non-waxy rice cultivars, growth responce as affected by leaf-removal treatment were examined in various fertilizer application. Vertical dry matter of culm was significantly decreased from ground upto 10cm. Culm dry matter of waxy rice was more steadily decreased than that of non-waxy rice. Starch content of culm in non-waxy rice was higher than waxy rice, and that in waxy and non-waxy rice were the lowest in three leaf-removal but no difference in single leaf-removal. Flag leaf in waxy rice and 2 nd leaf in non-waxy rice were dominantly affected yield by leaf-removal. The 1000-grain weight and rippend grain ratio of non-waxy rice were more higher than waxy rice and that in waxy and non-waxy rice were the lowest value in three leaf-removal but no difference in single leaf-removal treatments.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.2
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• pp.107-112
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• 2013

The aim of this study was to test hypothesis that low sink size could mitigate deterioration of grain filling characteristics under high grain filling temperature. To achieve this aim, we selected Donganbyeo as a tolerant and Ilpumbyeo as susceptible variety to high temperature during grain filling period through screening 6 rice varieties. Then their spikelets number and the ratio of superior and inferior spikelet were compared. Grain weight and head rice ratio of Ilpumbyeo decreased significantly in high temperature. Ilpumbyeo had more spikelets than Donganbyeo. However, there was no significant difference between two varieties in the ratio of superior and inferior spikelets. So we tried to investigate the varietal difference of grain filling characteristics with removing inferior spikelets. Removing inferior spikelet in both of varieties could recover grain weight but not improve head rice ratio under high temperature. These results showed that sink/source ratio affected grain weight but didn't affect head rice ratio. Therefore, new approach was required to improve head rice ratio beyond sink/source ratio under high temperature.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.1
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• pp.79-83
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• 1985

This experiment was carried out in order to determine the optimum harvesting time of tetraploid Italian ryegrass. Moisture content, 1000-seed weight, germination and seed shattering were investigated at six harvesting times after anthesis in 1984 at Suweon. The results are summarized as follows; 1. Seed moisture content was slowly decreased until 24 days and fastly decreased from 24 days after anthesis. The daily mean moisture loss during the ripening period was about 1.5 percentage. 2. The maximum 1000-seed weight was reached at 24 days after anthesis and 1000-seed weight of Waseking was heavier than that of Giant. 3. Shattering began at 17-20 days after anthesis and thereafter rapidly increased. 4. Germination was 50% at 10 days after anthesis and maximum germination was reached at 24 days. 5. Considering germination, 1000-seed weight and shattering, the optimum harvest time was 24 to 27 days after anthesis. At this time, moisture content was 55.0 to 43.5 percent and two to five seeds per ten spikes were shed by shaking at the vertical point.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.6
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• pp.443-447
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• 2002

This study was carried out to determine the differences in the growth, grain yield, and seed quality of sesame plant according to seeding date between P,E. vinyl-house and outdoor cultures. Reproductive growth period in vinyl-house culture was shorter than in outdoor culture. Stem length and capsule setting length of sesame were much longer in vinyl-house culture than in outdoor culture. Also, number of capsules per plant and 1,000 grain weight in vinyl-house culture were higher, specially the grain yield was approximately 57% more than in outdoor culture. In vinyl house culture, sesame plants sown on June 8 had longer capsule setting length, more capsules per plant, higher 1,000 grain weight, and higher percent ripened grain at the upper part of the capsule settings than those sown in May 9. They also had higher 1,000 grain weight at the middle and lower part of the capsule settings compared to May 9 seeding. However, no difference in grain yield of in seeding dates was observed. In outdoor culture, sesame plants, which was sown on May 9, had more effective branch number and capsule number and plant compared to those sown on June 8. Though sesame plants sown on May 9 had lower percent ripened grain at the upper and middle part of the capsule settings and lower 1,000 grain weight, the seed yield was similar to those sown on June 8. No difference in chromaticity value $L^*$ of sesame seeds between two culture conditions was observed. The $a^*$ value was higher in vinyl-house culture than outdoor culture while $b^*$ value was higher in outdoor culture. Sesaminol triglucoside content of sesame seeds was higher in vinyl-house culture than in outdoor culture. On the other hand, the content of sesamin and sesamolin from sesame seeds in vinyl-house culture were lower than in outdoor culture.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.3
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• pp.222-228
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• 1988

This experiment was carried out to investigate the effects of N levels (0,10,20,30kg/10a) and N split rates [the rates of basal＋top dressing 15 days after transplanting (DAT) : top dressing 25 days before heading (DBH) was 100 : 0, 80 : 20, 60 : 40 ] on the growth, yield, yield components, and N uptake of Seomjinbyeo (J) and Samgangbyeo (I${\times}$J). The maximum tillering stage occurred in the middle of July in both varieties, but Samgangbyeo showed the second maximum tillering stage in the middle of August probably due to the retarded early growth caused by low temperature in the tillering stage and to favoring temperature in August. Grain yield of Seomjinbyeo was similar among the N levels from 10 to 30 kg/10a without occurrence of rice blast and lodging, but that of Samgangbyeo increased as N level increased upto 30 kg/10a. Grain yield of Seomjinbyeo was higher when N was applied three times (basal and two top dressings 15 DAT and 25 DBH) compared with two times (basal and top dressing 15 DAT), but that of Samgangbyeo was not different among the N split rates. Total N uptake and the proportion of fertilizer N to the total N uptake increased as N level was higher. N uptake tended to be higher as proportion of basal＋top dressing 15 DAT increased in early growth stage, but it was higher as proportion of N applied 25 DBH increased in the late growth stage. The N efficiency to produce grain per absorbed N unit decreased as N level decreased in Seomjinbyeo, but similar in Samgangbyeo.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.7 no.1
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• pp.103-115
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• 1969

A study has been made on the time of nitrogen top-dressing and the method of top-dressing to establish the higher yielding cultural method for wheat at Suwon. In this experiment, it was observed that the application of nitrogen top-dressing with urea leaf spray as spike fertilizer increased the yield by 4~6 percent over nitrogen top-dressing of equal quantity only. Considering the yield and various factors concerned, it is reasonable to apply top-dressing on mid and late of March in Suwon area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.304-308
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• 1990

This study was conducted to increase the yield of sesame on the undeveloped upland by pinching and application of minor nutrients which were magnesium. boron and zinc. The effect of phinching to yield at 20 days after germination was 17%. and pinching effect at 50 days after germination with minor nutrients was 46% compared to non-treatments. These effect were considered as increasing the number of capsule per plant. number of node per main stem. and 1,000 grains weight. Simultaneously, the nutrients (Mg. B and Zn) were recognized to promote remarkably the yield.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.2
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• pp.156-164
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• 2015

High temperature stress would affect rice production in the future as heat wave is expected to occur frequently under climate change conditions. The objective of this study was to obtain rudimentary information to assess the impact of heat stress on rice yield and its yield component in Korea. Two rice cultivars "Hwaseongbyeo" (Japonica) and "Dasanbyeo" (Tongil-type) were grown at different nitrogen fertilization levels in two seasons. These cultivars were grown in 1/5000a Wagner pot placed within four plastic houses where temperature was controlled at ambient, ambient$+1.5^{\circ}C$, ambient$+3^{\circ}C$ and ambient$+5^{\circ}C$ throughout the rice growing season in Suwon ($37^{\circ}16^{\prime}N$, $128^{\circ}59^{\prime}E$), Korea. The degree of temperature change affected grain yield whereas the level of nitrogen had little impact on grain yield. The number of panicle per pot and spikelet per panicle were not significantly different among temperature treatments in both cultivars tested. In contrast, 1000-grain weight and ripened grain ratio were decreased significantly under the treatments raising the air temperature to the level of $5.0^{\circ}C$ and $1.5^{\circ}C$ above the ambient air temperature in Dasanbyeo and Hwaseongbyeo, respectively. Reduction of 1000-grain weight and ripened grain ratio under the temperature treatments of $3.0^{\circ}C$ and $5.0^{\circ}C$ above the ambient air temperature resulted in significantly less grain yield for Dasanbyeo and Hwaseongbyeo, respectively. The greater sensitivity of grain yield to temperature increase in Dasanbyeo was attributable to the sharp decrease of 1000-grain weight and ripened grain ratio with the temperature rise above $23^{\circ}C$ during ripening period. On the other hand, Hwaseongbyeo had little variation of them in the temperature range of $23-27^{\circ}C$. These results suggested that grain yield would decrease under future climate conditions due to grain weight decreased by shorter grain filling period as well as the ripened grain ratio reduced by spikelet sterility and early abortion of rice kernel development. Thus, it would be essential to use cultivars tolerant to heat stress for climate change adaptation, which merits further studies for developing varieties that have traits to avoid spikelet sterility and early abortion of rice kernel, e.g., early morning flowering, under heat wave.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.3
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• pp.171-183
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• 2016

The effects of weather variations on winter hulless barley were analyzed using data obtained from winter crop situation test at Iksan from 1985 to 2015. The wintering stage in the 16 years from 2000 to 2015 has become colder and shorter than that in the previous 15 years from 1985 to 1999. This has resulted in an early sequence of regrowth date, heading date, and ripening date. Heading date of hulless barley was mostly influenced by regrowth date and period of stem elongation. Futher, the regrowth date and period of stem elongation were strongly negatively correlated with the average air temperature in February and the maximum air temperature in March, respectively. The number of spikes per $m^2$ and 1000-grain weight of Saechalssal cultivated from 2003 to 2015 showed strong positive correlations with yield. In early heading years, yield increased with extended ripening period and with increased 1000-grain weight. There was a strong negative correlation between 1000-grain weight and the average temperature during the ripening period. In the 15 years from 1985 to 1999, warm winters contributed to yield increase with increase in the number of spikes per $m^2$ and a long ripening period. In contrast, in the recent 16 years from 2000 to 2015, the large variability in air temperature during the wintering stage, the decreasing number of spikes per $m^2$ and the steadily increasing air temperature and decreasing precipitation during the ripening stage have caused high temperature stress and yield loss in late heading years.