• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.32-40
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• 2006

The nitrogen (N) absorption and partition of the rice plants are important indicators that can be used to improve the N use efficiency (NUE) of the plants. Improving the plant NUE can help to avoid nutrient waste that may cause environmental pollution. To investigate the N absorption and partition of the rice plants, Hwaseongbyeo (Japonica) and Dasanbyeo (indica/japonica) were applied with N fertilizers at the rates of 60, 120, and 180 kg N per ha in paddy field. Also micro plots of $0.81m^2$ were established inside each plot for application of $^{15}N-labeled$ fertilizer. The differences in N utilization of the rice plants were associated with the total N absorption and partitioning after the heading stage. In the grain filling period, the increase of nitrogen content in the total and leaf blades of Dasanbyeo was higher than that of Hwaseongbyeo. Soil N was the main contributor for the increase of total N of Dasanbyeo during the grain filling period. The N fertilizer uptake rate of Hwaseongbyeo rapidly increased with the increment of N fertilization rate. In Dasanbyeo, N fertilizer uptakes were similar under all rates and times of N application. From heading stage to harvest, Dasanbyeo continued accumulating nitrogen, whereas Hwaseongbyeo had small changes. In conclusion, the difference in nitrogen absorption and partition after heading of the two cultivars was caused by the ability of Dasanbyeo to accumulate and remobilize soil nitrogen to the grains during the grain filling period.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.127-131
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• 2002

Critical nitrogen concentration (Nc), which is defined as the minimum % N in shoots required to maintain the maximum growth rate of top dry weight (W) at any time, was determined for rice plant. Using two rice varietal groups, japonica varieties and an indica $\times$ japonica "Dasanbyeo", 18 data points fulfilling the statistical criteria for determining Nc were obtained through eight N-fertilization experiments over two years at Suwon (37$^{\circ}$16'N), Korea. Nc dilution curve for each variety was obtained by fitting the Nc-W relationship to power function. However, The critical nitrogen curves for the two variety groups were not different statistically. Thus, a Nc dilution curve was fitted for the Nc data points pooled over the two variety groups and proposed in rice as: Nc=4.08, where W＜1.73 t h $a^{-1}$ , Nc=5.197 $W^{0.425}$3/ ($R^2$=0.964), where 1.73 t h $a^{-1}$ ＜W＜12 t h $a^{-l}$. The Nc for W＜1.73 t h $a^{-l}$ were estimated as a constant value of 4.08%, the mean value of the maximum N concentration for N-limiting condition and the minimum N concentration for N non-limiting condition. The model for Nc is applicable to diagnosing the nitrogen nutrition status during the rice growth period from emergence to heading stage. The Nc curve well discriminated the 144 data points between the N limiting and the N non-limiting groups regardless of varieties, cultural methods, and years.-limiting groups regardless of varieties, cultural methods, and years.

• Applied Biological Chemistry
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• v.31 no.2
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• pp.211-216
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• 1988

Brown rices were abrasively milled to give 92% yield, and hydration and cooking rates of brown and milled rices were investigated. Diffusion coefficients of Japonica brown and milled rices at $30^{\circ}C$ were smaller than those of J/Indica counterparts. The bran layer controlled the diffusion coefficients of brown rices at initial stage of hydration. The diffusion coefficients for Japonica and J/lndica milled rices were $107{\sim}114$ and $74{\sim}87$ times greater than those for brown rices, respectively. The terminal points of cooking of brown and milled rices at $110^{\circ}C$ were similar among varieties. The cooking rate constants of milled rices were about 2-fold compared with those of brown rices.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.4
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• pp.460-470
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• 1985

Experiments were carried out to evaluate the standard gravity in determining potential kernel size and to determine the effective sampling way by analyzing intra - and inter - plant variations for some source and sink characters using eleven semi-dwarf indica and three japonica cultivars including four semi-dwarf indica nearisogenic lines. Also, additional experiments were conducted to understand yearly variation and variety x year interaction effects for ten characters related to source and sink and to characterize the varietal difference of pre- and post-heading self-competition employing three parental varieties and their F$\sub$5/ progenies in 1982 and 1983. It is desirable to determine the potential kernel size by average kernel wight of rice grains showing above 1.15 specific gravity. There was significant difference in leaf area per tiller, spikelets and sink capacity per panicle among vigorous, intermediate and inferior tillers classified by differentiated order and vigorousness. Although it was difficult to find out any significant difference in grain-fill ratio, ratio of perfectly ripened grain, potential kernel size and sink/source ratio between vigorous and intermediate tillers, there was big difference between them and inferior one. The coefficients of variation within each tiller-group for some characters related to source and sink were larger with the order of vigorous tillers < intermediate one '||'&'||'lt; inferior one, and the average heritability of all characters, evaluated by the ratio of varietal variance (equation omitted) to total variance (equation omitted), were higher with the order of inferior tillers '||'&'||'lt; intemediate one '||'&'||'lt; superior one. Therefore, it is desirable to sample the vigorous tillers to represent the varietal difference of these traits. '82-'83 year variations of three parental cultivars were significant for all traits except for leaf area/tiller, panicles/hill, leaf area index and rough rice yield. The characters showing highly significant variance of variety x year interaction were growth duration from transplanting to heading, leaf area/tiller, sink/source ratio, sink capacity/panicle and grain yield. Generalized yearly response of three parental varieties (Suweon 264, Raegyeong, IR1317-70-l) and their F$\sub$5/ progenies on the 1st and 2nd principal components extracted from ten source and sink characters generally exhibited reduction in both source and sink. However, there were diverse variety x year interactions such as progenies showing similar reaction with their parents and intermediate or recombinational yearly response with little or considerable yearly movement on the four-dimensional planes of the two upper principal components between 1982 and 1983. Sink characters revealing highly significant border effect were grain-fill ratio, spikelets and sink capacity per panicle. Among them the latter two especially showed significant variety x border effect interaction. Self-competition characterized by relative weakness of inside plant's sink characters compared to the border one was more severe during the reproductive stage before heading than maturing stage. Though the larger sink capacity per panicle generally disclosed the severer self-competition, some lines (like Suweon 264) revealed severe self-competition with small sink capacity while a few others showed tender self-competition in spite of big sink capacity per panicle.

• Korean Journal of Food Science and Technology
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• v.23 no.1
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• pp.57-61
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• 1991

Rheological properties of Tongjinbyeo(Japonica) and Samgangbyeo($J{\times}Indica$) rice starches gelatinized with thermal or alkali solutions were investigated with rotational viscometer(Brabender Viscotron). The two starches showed Bingham pseudoplastics behavior in $4{\sim}8%$ thermal or alkali gelatinized starch solutions. Rheological properties of thermal gelatinized starch solutions were similar between the two varieties. However, alkali gelatinized Samgangbyeo starch solutions showed higher values of yield stress and consistency index than that of Tongjinbyeo starch. The values of pseudoplasticity, yield stress and consistency index were higher in the thermal gelatinized samples than those of in the alkali gelatinized ones.

• Applied Biological Chemistry
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• v.33 no.2
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• pp.105-108
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• 1990

The numbers of aleurone layers and thickness of pericarp of waxy rice in dorsal side were higher than those in vental side, However, varietal characteristics of the bran structures were observed. The water uptake rates of brown rice at $60^{\circ}C$ were similar between $j{\times}indica$ varieties(Hangangchalbyeo, H and Baegunchalbyeo, B) and higer than that of japonica variety (Shinsunchalbyeo, S). Inherent viscosities for H, B and S waxy rice starches were 1.92, 1.84 and 1.73 $dlg^{-1}$, respectively. The minimum moistures for gelatinization of waxy rice starches determined by DSC were $36.4{\sim}38.6%$ which represented 4moles of water per mole of hexose unit.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.1-10
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• 1982

Degree of grain shattering which is of varietal character is an important determinant for the magnitude of field loss of grains during harvest and threshing. Seven Indica \times Japonica progeny varieties and four Japonica varieties were subjected to measurements of tensile strength of grains, degree of grain shattering when panicles were dropped at 1.5m above concrete floor, and moisture content of grains (wet basis) during a period 35 to 63 days after heading. In addition, two varieties were tested for the relation of tensile strength of grains to the magnitude of field loss of grains in actual binder harvest. The 11 varieties differed conspicuously in tensile strength of grains and the degree of grain shattering: the weakest average tensile strength of grains of a variety was about 90g and the strongest about 250g with varying standard deviation of 30 to 60g. Three Indica \times Japonica varieties and one Japonica variety shattered I to 30% of the grains under the falling test. The threshold tensile strength of grains allowing grain shattering was estimated to be 180g on average for a sampling unit of 10 panicles, but only the grains having tensile strength weaker than 98g within the samples shattered. A decrease in average tensile strength by 10g below the threshold value corresponded to an increase of 3 to 5% in grain shattering. Most varieties did not change appreciably the tensile strength of grains and degree of grain shattering with delay in time of harvest and showed a negative correlation between the tensile strength and the moisture content of grains. The average tensile strength of grains was negatively correlated linearly with field loss in binder harvest. The average tensile strength for zero field loss in binder harvest was estimated to be 174g and a decrease in the average tensile strength by 10g corresponded to an increase of 40kg per hectare in field loss of grains. Instead of the average tensile strength of grains, the percentage of grains having tensile strength weaker than 100g is recommended as a criterion for the estimation of field loss of grains during harvesting operations as well as a basis of variety classification for grain shattering, since the standard deviation of tensile strength of grains varies much with variety and time of harvest, and individual grains having tensile strength stronger than 98 did not shatter practically.

• Korean Journal of Weed Science
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• v.6 no.1
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• pp.48-58
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• 1986

In order to eluciate the factors affecting the injury caused by simetryne(2-methyl thio-4,6-bis(ethylamino)-S-triazine) to rice plants of Tongil variety(Indica ${\times}$ Japonica), the leaching properties of simetrynes, compared with Japonica varieties, Mangyeung and Sadominori were investigated. Bioassay technique and $^{14}C$-simetryne for leaching study and bioassay for the characteristics of the rice plants were employed. The leaching range of simetryne was very narrow regardless of soil types under upland soil conditions but it increased little in Silt clay soil and greatly in Sandy loam soil under flooded soil conditions. The amount of the roots of Tongil Jas a little more than that of Mangyeung and the roots of the Tongil mostly distributed near the surface soil while those of Mangyeung rooted deep into the soil. The foliage area and the rate of transpiration of Tongil were larger and greater than those of Mangyeung by 1.3 times and 1.65 times, respectively. The sensitivity of Tongil to simetryne was about 3 times larger than that of Sadominori in water culture.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.2
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• pp.59-68
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• 1984

The Purpose of this study was to investigate the effect of the change in misture content on some physical properties of grains, and some relations amont the properties. Materials included ere rough rice, brown rice, barley and wheat with the range of moisture content of 6~26 percent, 7~25 percent, 10~24 percent and 6~22 percent, respectively. Kernel dimension, sphericity, kernel weight, and volume were included as the physical properties of the grains. The results obtained are summarized as follows; 1. The ratio of grain length to the thickness was in the range of 3.59~4.16 for rough rice(Indica type), 2.98~3.27 for rough rice(Japonica type), 3.25 for brown rice (I.T.), 2.14~2.38 for brown rice(J.T.), 2.92~3.13 for barley and 2.10~2.21 for wheat, respectively. 2. The sphericity was found to be 42 percent for rough rice(I.T.), 48 percent for rough rice(J.T.), 52 percent for brown rice(I.T.), 62 percent for brown rice(J.T.), 45 percent for barley and 61 percent for wheat, respectively. 3. The kernel weight of grains was linealy increased with the increase of moisture content. At a specified moisture centent of 14 percent, the kernel weight was shown to be in the range of 4.72${\times}10^{-5}$~3.58${\times}10^{-5}$kg for wheat, 3.60${\times}10^{-5}$~3.12${\times}10^{-5}$kg for barley, 2.80${\times}10^{-5}$~2.35${\times}10^{-5}$kg for rough rice, and 2.24${\times}10^{-5}$~1.82${\times}10^{-5}$kg for brown rice, respectively. 4. The kernel volume was linearly increased with increase of moisture content. The rate of increase was significantly low for rough rice in comparison with the remaining grains. The kernel volume, at a specified moisture content of 14 percent, was in the range of 3.51${\times}10^{-8}$~2.76${\times}10^{-8}m^3$ for wheat, 2.84${\times}10^{-8}$~2.43${\times}10^{-8}m^3$ for barley, 2.93${\times}10^{-8}$~1.97${\times}10^{-8}m^3$ for rough rice, and 1.61${\times}10^{-8}$~1.29${\times}10^{-8}m^3$ for brown rice, respectively. 5. The kernel volume of grains was found to be related to the length, width, thickness and kernel weight as a exponential function. The kernel volume was shown to have correlation coefficient to the length factor rough rice and barley which were of low sphericity, while the width factor was predominant for brown rice and wheat which was of high sphericity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.3
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• pp.398-405
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• 1995

In termperate zone planting rice at different date subjects the crop to different climatic condition. This study aimed at comparison of the change in source-sink relationship of the Japonica(J) and that of Indica Japonica(I$\times$J) type rice cultivars caused by shift of heading date. Two J-and two I$\times$J-type cultivars were made to head on Aug. 16, Aug. 26 and Sep. 5. Percent grain fertility was not changed in response to shift of heading date. Ripening patterns of 4 rice cultivars were similar to sigmoid curve type but when the heading date was delayed to Sep. 5, the form is changed to log type of curve. In J-type, physiological maturity was delayed about 5 day when headed at Sep. 5, in compare to headed at Aug. 16 and Aug. 26. However ripening was continued about 10 days when the diurnal, nocturnal and minimum temperature was above 17, 12$^{\circ}C$ and about 3~8$^{\circ}C$. In I$\times$J hybrid, real ripening was continued when the diurnal, nocturnal and minimum temperature was over 20, 17$^{\circ}C$, but if the minimum temperature was downed bellow 1$0^{\circ}C$, it was impossible. Simulated photosynthetic amount based on photosynthetic ability, temperature, leaf area and day length was varied according to changes in heading date and it was decreased seriously if the minimum temperature was fall down bellow 4$^{\circ}C$ in field, that's why decrease in photosynthetic ability and aging. The temperature range of optimum ripening was 21~26$^{\circ}C$, if there is nothing hindering factor.