• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.2
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• pp.137-143
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• 2008

Rapid canopy closure (RCC) is one of the physiological attributes that may enhance genetic yield potential of rice (Oryza sativa L.) in a growing season. Crop growth before canopy closure could be described by an exponential equation of $y\;=\;{\alpha}{\cdot}{\exp}({\beta}{\cdot}t)$ where $\alpha$ is the crop leaf area index (LAI) or shoot dry weight (DW), t is the thermal time, $\beta$ is the LAI or DW at the beginning of the exponential growth and is the relative growth rate of LAI ($m^2m^{-2}^{\circ}C^{-1}$) or DW($gg^{-2}^{\circ}C^{-1}$). Field experiment using 22 cultivars revealed that the exponential growth phase before canopy closure can be divided into two sections; an earlier section during which crop dry weight and LAI of varieties are highly dependent on $\alpha$ and a second section where crop dry weight and LAI are highly dependent on $\beta$. Grain weight had significantly positive correlation with $\alpha$ parameter and dry weight and LAI during early exponential phase. The parameter $\beta$ of the exponential growth curve had positive and significant correlation with the LAI and dry weight during the late exponential growth phase, grain number per unit area, and grain yield. There was genotypic difference for RCC parameters, $\alpha$ and $\beta$, indicating the possibility of genetic improvement for these traits.

• Korean Journal of Weed Science
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• v.7 no.2
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• pp.139-143
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• 1987

This experiment was conducted to investigate the effect of herbicide on the photosynthetic activity of the weed and rice plant. Two rice cultivars "Nongbaeg" and "Taebaegbyeo" were tested with butachlor, Molis-M, and perfluidone at 5 days after transplanting. Bentazone and propanil were sprayed at 25 days after transplanting. Photosynthetic activity was varied with herbicide and varieties. Generally, application of herbicide resulted in decreased photosynthetic activity. Indica ${\times}$ Japonica variety showed more sensitive to herbicide than Japonica variety. Recovery of the photosynthetic activity was faster in the bentazon than the propanil.

• Korean Journal of Weed Science
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• v.13 no.1
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• pp.62-70
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• 1993

There was intraspecific variation in Echinochloa crus-galli var, crus-galli in response to quinclorac, showing that plan height and dry weight of a locally collected barnyardgrass(Chinjupi) from Chinju were 90.5 and 37.8% of the untreated control, while those of a locally collected one(Iripi) from Iri showed 19.1 and 14.4%, respectively. The normal distribution curve was obtained from frequency distribution of 89 rice cultivars as affected by the application rates of quinclorac at 30, 300, and 3,000g ai/ha. Protein patterns(SDS-PAGE) of two barnyardgrasses belonging to E, crus-galli var. crus-galli such as Iripi and Chinjupi were not affected by the quinclorac application, indicating that inhibition of enzyme and/or protein biosynthesis seems to be not the primary action target of quinclorac. Electronmicroscopic observation on the injured leaf of Iripi which is considered as a susceptible one showed prominent membrane disruption. Chuchungbyeo(rice variety) resulted in a greater inhibition of tomato growth than those from Chinjupi or Iripi, indicating a great amount of quinclorac discharged from rice root, Chinjupi which is relatively tolerant to quinclorac than Iripi, discharged more quinclorac causing a greater inhibition of tomato growth.

• Korean Journal of Breeding Science
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• v.40 no.4
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• pp.414-421
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• 2008

We conducted a QTL analysis of agronomic traits using 117 $BC_3F_5$ and $BC_3F_6$ lines developed from a cross between Ilpumbyeo and Moroberekan. Genotypes of 117 $BC_3F_5$ lines were determined using 134 simple sequence repeat (SSR) markers. A total of 832 Moroberekan chromosome segments with 410 homozygous and 422 heterozygous, respectively, were detected, and the genetic distance of introgression segments ranged from 0.5 cm to 112.1 cm. A linkage map constructed using 134 SSR markers was employed to characterize quantitative trait loci (QTL). The 117 $BC_3F_5$ and $BC_3F_6$ lines were evaluated for seven agronomic traits at two locations in 2006 and 2007 and at one location in 2007. A total of 26 QTLs were identified for seven traits including days to heading, and the phenotypic variance explained by each QTL ranged from 9.2% to 24.2%. Moroberekan alleles contributed positive effects in the Ilpumbyeo background at eleven QTL loci including panicle length and spikelets per panicle. Five QTLs, two for days to heading and one each for culm length, panicle length and spikelets per panicle were consistently detected in every occasions indicating that these QTLs are stable. Among them, two QTLs, spp6 for spikelets per panicle and pl6 for paniclel length were localized in the similar region. Increase in spikelets per panicle at this locus might be due to the increase in panicle length, because both traits were associated with increase in spikelets per panicle and panicle length due to the presence of the Moroberekan allele. These Moroberekan QTLs might be useful in breeding programs to develop high-yielding cultivars.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.4
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• pp.471-480
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• 1985

Recently several synthetic chemicals inhibiting biosynthesis of gibberellic acids were found to be effective in preventing cereal crops from lodging by reducing culm length. The present study aimed to clarify the extent of practical manipulation of the culm length of the rice crop by changing the endogenous level of gibberellic acids with exogenous application of GA$_3$ or GA biosynthesis inhibitor. Three rice cultivars, 'Jinheung', 'Minehikari' (Japonica) and 'Hangangchal' (semi-dwarf Indica x Japonica) were treated with GA$_3$ (0, 20, 50 and 100 ppm solution) and an anti-gibberellin, paclobutrazol (0, 100, 200 and 300 g ai/ha) at three growth stages (maximum tillering, panicle initiation and meiotic stage), respectively. The application of GA$_3$ (50, 100 ppm) at maximum tillering stage and panicle initiation stage promoted the elongation of the 5th internodes from the top and GA$_3$ applied at meiotic stage promoted remarkably the elongation of the 3rd internodes. Culm was most elongated when GA$_3$ was applied at maximum tillering stage in 'Jinheung', at panicle initiation stage in 'Minehikari' and at meiotic stage in 'Hangangchal'. Paclobutrazol shortened the 4th and 5th internodes from the top when it was applied at maximum tillering stage and panicle initiation stage and the 2nd and 3rd internodes when it was applied at meiotic stage in the three cultivars. The semi-dwarf Indica x Japonica variety responded to a greater extent to the GA$_3$ and to a less extent to the anti-gib berellin than the Japonica varieties. The effect of GA$_3$ and paclobutrazol on the panicle length and the number of spikelets per panicle varied with time and dose of their application as well as with variety.

• Journal of Life Science
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• v.9 no.2
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• pp.121-126
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• 1999

Some attempts were made to investigate the honeydew excretion of the brown planthopper(BPH), Nilaparvata lugens Stal, biotypes in terms of instal nymph, days after emergence, macropterous and brachypterous mated and unmated female, and macropterous female with different sources fed on 60-day-old rice cultivars with different resistance genes. The feeding amount of the BPH biotypes was measured by using the honeydew excretion test. The feeding amount of fifth instar on Miryang 23 with no resistance gene was higher than that of Cheon-gcheongbyeo with Bph-1 gene by two times. Macropterous and brachypterous females showed low feeding amount at first day after emergence, but they showed high feeding amount from second days after emergence. Also the feeding amount of brachypterous female was higher than that of macropterous female. In addition, the feeding amount of BPH was in the order of nymph

• Korean Journal of Weed Science
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• v.3 no.1
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• pp.57-68
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• 1983

To estimate the possible amount of weed-crop competitions under the various cropping patterns of two rice cultivars of different type, comparisons between weedy check and weed-free plots in plant height, tillering number, and plant weight were investigated. Fluctuations in Importance Value, competition value, and net productivities were used to discuss the crop-weed competition, respectively. As a result, differences in dominant weed species, competitive crop variety, most effective cropping pattern, and crop yielding characteristics under the different weed competitions were investigated, respectively.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.45-53
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• 2006

The objectives of this study are to determine the primary yield components responsible for yield differences in a subtropical environment of the Hunan province China and in a temperature environment of Honam province Korea. Field experiments were conducted in a subtropical environment in Hunan province China during 2002 and in a temperate environment in Honam province Korea during 2003. Seven rice cultivars were grown under optimum crop management in each experiment field. Yield, yield components and plant dry matter were determined at maturation. The highest yield (567 kg/10a) was produced at Honam province by Jinyou 207, a Chinese cultivar, The maximum yield at Hunan province was 453 kg/10a by Sanyou 63. On the average across cultivars, Honam produced 23% greater yields than Hunan. Sink size (spikelets per $m^2$) was responsible far these yield differences. Panicle number per $m^2$ was much greater at Honam.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.5
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• pp.580-586
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• 1995

Soil temperatures at depths of 1~5cm are important to the germination and emergence of dry seeded-rice. An automated weather station was used to monitor the hourly weather parameters at Experiment Farm, Kyung Hee University from April 21 to May 30 in 1994. The data was analyzed to figure out the 24-hour temporal changes in air 1.5m above ground and soil temperatures under ground of 0, 2.5, 5, 10 and 20cm. The fluctuations of soil temperature were greatest at the soil surface and decreased with increasing depth. Mean soil temperatures at depth of 2.5cm were about 3$^{\circ}C$ higher than mean air temperatures during the observation period. Although mean soil temperatures at depth of 2.5cm during 10 or 15 days after April 21, May 1 and May 11 showed almost same temperatures, the distribution patterns of temperature regime were different from each other. Rice cultivars, Hwasung, Seohae, Nampung, IR60 and CR155, were seeded at depth of 2.5cm on April 21, May 1 and May 11, respectively. The periods of seedling emergence(PSE) varied in accordance with cultivars and seeding dates. PSE was correlated with accumulated daily mean air temperatures and accumulated hours classified by temperature regimes.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.250-257
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• 1988

The study was intended to know any relations between the rice tolerance to bensulfuron and varietal speciation in seed protein composition or any enzymatical allelies with or without chemical treatment. Rice varieties used were UCP-28, Chinsurah Boro II, Fukunohama, Fadehpur-2, IR 14252-13-2-2-5 as the tolerant group, and HP 93(3) FA, HP94(9) FA, Padilabou Alumbis, KH-17854, and IR 1846-2841-1 as the susceptible, respectively. Electrophoretic methods used were SDS-PAGE for seed protein, 7% PAGE for isozymes (acid phosphatase, peroxidase, malate dehydrogenase, and esterase from rice seedling) and variation in isoenzyme profiles (malate dehydrogenase, peroxidase, and esterase) as affected by different concentrations of bensulfuron(0, $10^{-6}$, $10^{-5}$ and $3{\times}10^{-5}M$) was also studied. The results are summarized as follows. -Among 16 bands separated in seed proteins, two different rice groups selected in terms of tolerance to bensulfuron were clustered in dissimilarity, which was based on relatively larger area in whole peaks and higher activities in N, O, P bands for the tolerant group. -Among isozymes obtained from rice seedlings without chemical treatments, the following specificities were obtained. The tolerant varieties had the relatively higher activity in D band out of 4 peroxidase bands. Malate dehydrogenase was separated into 3 bands and only tolerant varieties had A band and higher activities in Band C bands. Esterase was separated into 3-4 bands with higher activities in A and B bands for tolerant varieties. There were one major band accompanied by 2-3 minor bands for acid phosphatase in which only tolerant varieties had the B band. -The effect of Bensulfuron concentration on the isozyme activities showed that the activity of C band in peroxidase was not present in tolerant varieties which was contrary to the increased activities in susceptible varieties. However, D band was gradually disappeared only in susceptible varieties as the concentration of bensulfuron was increased. For malate dehydrogenase in the susceptible varieties, major bands D, E and F kept consistantly higher activities while minor bands A, B and C disappeared sensitively. Among 5 bands of esterase separated, D band was present only in the tolerant varieties while E band only in the susceptible. The activities in A, C, E bands were sharply decreased in the susceptible varieties as the concentration of bensulfuron was increased.