• Korean Journal of Soil Science and Fertilizer
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• v.4 no.2
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• pp.161-166
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• 1971

1. Increment of applied $SiO_2$, N and K effected Significantly the rice yield in Akiochi soil. Nitrogen fertilizer, however, should be split in several times. 2. The applied silica accelerated the nitrogen efficiency in particular when the increased nitrogen fertilizer was applied. 3. The number of hill per plant was increased by increasing nitrogen application, while percent of maturity was decreased. But application of increased Potassium gave remarkerbly high percentage of maturity. 4. Application of silica to the Akiochi soil increased both the number of spikelets and percentage of maturity of rice. 5. The increased application of nitrogen raised nitrogen content in plant but decreased the content of silica and potassium. The ratio of $SiO_2/N$ and $K_2O/N$, therefore, decreased. 6. From the results it can be concluded that application of increased nitrogen to the Akiochi soil should be accompanied by application of increased $SiO_2$ and K.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.15
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• pp.61-67
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• 1974

Field experiment was conducted to disclose some effects of leaf defoliation in heading time and the application of different combinations of nitrogen, phosphorus and potassium on the maturity and yield of paddy rice. The results obtained are as follows; 1.All were components considered were increased as the amounts of nitrogen, phospgorus and potassium applied were increased, except the maturity rate had the tendancy to be decreased with the increase of the above fertilizer applications. 2.As the rate of cutting leaves went higher, the weight of rough rice, the maturity rate and the weight of 1, 000 kernels of perferct brown rice were decreased, and there were significant differences among the treatments of leaf blade cutting. 3. The contribution of each leaf to yield through the maturity, number of spikelets per panicle and 1, 000 kernel weight were 61.87-66.18-65.61% respectively for the flag leaf, 17.50-20.65-23.41%for the 2nd leaf, 12-71-12.73-10.11%for the 3rd lead and 7.93-6.44-0.87%for the 4th leaf respectively. This simply indicared that the effects of the leaves to the yield were decreased as their position went down. This tendency was specially emphasized in the case of the weight of 1, 000 kernels of perfect brown rice.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.306-316
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• 2015

An experiment in a controlled environment was conducted to evaluate the genotypic differences of grain yield and yield-related elements of rice under elevated air temperature. Eight rice genotypes included in three maturing group (early, medium, and medium-late maturing group) were grown with 1/5,000 a Wagner pots at four plastic houses that were controlled to the temperature regimes of ambient temperature (AT), $AT+1.5^{\circ}C$, $AT+3.0^{\circ}C$, and $AT+5.0^{\circ}C$ throughout the rice growing season in 2011. Ripened grain ratio and 1000 grain weight showed the most susceptible and tolerant responses to elevated air temperature, respectively. The grain yield reduction was attributable to the sharp decrease of ripened grain ratio. Grain yield was significantly decreased above the treatment of $AT+1.5^{\circ}C$ and $AT+3.0^{\circ}C$ in early maturing group and the others, respectively. Highly correlation to average temperature from heading to 20 days was revealed in yield (r = -0.69), ripened grain ratio (r = -82), fully-filled grain (r = -70), and 1000 grain weight (r = -0.31). The responses of yield and yield-related elements except number of spikelets and panicle to elevated air temperature were fitted to a logistic function. The parameters of logistic function for each elements except grain yield could not be applied to the other varieties. In conclusion, yield and yield-related elements responded differentially to elevated air temperature according to maturity groups and rice varieties. Ongoing global warming is expected to decrease the grain yield not only by decreasing the grain weight but also decreasing the ripened grain ratio in the future. However, the yield reduction would be mitigated by adopting and/or breeding the less sensitive varieties to high temperature.

• 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 Agricultural and Forest Meteorology
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• v.20 no.1
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• pp.135-143
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• 2018

The effect of elevated temperature on temperate paddy rice will be significant for dependable food supply in East Asia. Using temperature gradient field chamber (TGFC), which was designed to make the horizontal air temperature gradient by $0^{\circ}C$ to $3^{\circ}C$ higher than outside, we examined the measurement to understand the effects of extremely high temperature on paddy rice. In particular, the data of the year 2016, the worst heat wave in over 22 years, was analyzed in this study. The rice height in the relatively warmed condition was rapidly increased during early growth stage. However, the average grain weight and number of spikelet per panicle in the warmed chamber condition were gradually declined with increasing air temperature averaged for 40 days after first heading in each chamber. In particular, the grain yield was more dramatically decreased by the raising temperature because the percent ripened grain was quickly dropped as getting over the threshold temperature for pollination. Therefore, the surplus photosynthetic product by such lower grain filling rate may disturbed the decreases of the NDVI (Normalized Difference Vegetation Index) and SPAD chlorophyll values after first (normal) heading. In addition, the late-emerging head grain were appeared. However, this yield was too small to recover the normal yields decreased by extremely high temperature condition. Our result represented that the warmed condition in 2016 would be the critical limit for the stable yield of temperate paddy rice.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.1
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• pp.25-29
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• 1975

The weekly change of sugar and starch content in unfilled grain of Jinheung (temperate rice var.) and IR667-Suweon 214 (tropical rice var.) and of filled grain ratio (less than specific gravity 1.06 for Jinheung and 1.03 for IR667), filled grain weight and unfilled grain weight from flowering and the relationship among them were as fallows. 1. Total sugar content in unfilled grain was twice in Jinheung than in IR667 and starch content was higher (about 2.5 to 3.5%) in Jinheung but starch/sugar ratio was greater in IR667. Thus IR667 that was classified as high sugar type in leaf sheath and internode appears to be high starch type in sink (grain). 2. Under the favorable condition the weight of unfilled grain reached to minimum value and followed by maximum filled grain ratio and lastly by maximum weight of filled grains per ear. 3. Sugar and starch content gradually increased and then decreased during ripening and the maximum values reached prior to maximum filled grain ratio (6 weeks). Sugar content reached to maximum much earlier than starch content did and increased again from 8 weeks later. 4. Starch/sugar ratio reached to maximum value earlier than maximum starch content and earlier in IR667 than in Jinheung. 5. Maximum starch content of unfilled grain in Jinheung was 51.1%.

• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.631-642
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• 2012

This study was carried out to determine the effect of SCB compost leachate on the growth and yield of rice. Field experiment was conducted on sandy loam soil under the different fertilizer management; 80%, 100%, 130% N level of SCB leachate based on 13kg N/10a of conventional farmer application level and chemical fertilizer as control. The plant height and tiller's number of 80 and 100% N levels of SCB leachate were lower than that of the chemical fertilizer plot. But in the plot of 130% N level of SCB leachate the plant height and tillers was higher than that of chemical fertilizer. And the SPAD reading value of leaf in plot of 130% N level was higher than that of the chemical fertilizer. Rice yield in the 80% and 100% SCB leachate was increased from 12 to 13% that of plot of chemical fertilizer. But rice yield of 130% N-level was decreased 7% compared with chemical fertilizer. Rice quality of the application levels of 80 and 100% SCB leachate levels was significantly better than those of chemical fertilizer and 130% level of SCB leachate. In conclusion, the 100% N application of SCB leachate was improved yield and quality of rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.4
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• pp.324-331
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• 1991

To establish the direct seeding cultivation method in rice (Oryza sativa L.). direct subsurface seeding with different oxygen suppliers and seeding rates was conducted from May to Oct. 1989. at the experimental field of Suncheon National University. In direct subsurface seeding. calcium peroxide enhanced the ratio of seedling establishment. However. as number of plants per unit area increased. the occurrence of field lodging became progressively severe. so that the enhanced seedling establishment did not increase the yield. The optimal seeding rate and the number of sowing seeds per equally spaced spot were estimated to be 3.3Kg seeds/l0a and 3 seeds per spot with CaO$_2$-coated seeds. and 5.6Kg/10a and 5 seeds per spot with uncoated seeds. respectively, According to the results from the path coefficient analysis. percent of filled spikelets was identified to be the most influential variables on the variability in brown rice yield. so that improving percent of filled spikelets by inhibition of field lodging was the most important matter to increase the yield.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.04a
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• pp.120-120
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• 2022

• Proceedings of the Korean Society of Crop Science Conference
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• 2021.04a
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• pp.97-97
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• 2021