• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.5
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• pp.394-406
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• 2004

A split-plot designed experiment including four rice varieties and 10 nitrogen levels was conducted in 2003 at the Experimental Farm of Seoul National University, Suwon, Korea. Before heading, hyperspectral canopy reflectance (300-1100nm with 1.55nm step) and nine crop variables such as shoot fresh weight (SFW), leaf area index, leaf dry weight, shoot dry weight, leaf N concentration, shoot N concentration, leaf N density, shoot N density and N nutrition index were measured at 54 and 72 days after transplanting. Grain yield, total number of spikelets, number of filled spikelets and 1000-grain weight were measured at harvest. 14,635 narrow-band NDVIs as combinations of reflectances at wavelength ${\lambda}l\;and\;{\lambda}2$ were correlated to the nine crop variables. One NDVI with the highest correlation coefficient with a given crop variable was selected as the NDVI of the best fit for this crop variable. As expected, models to predict crop variables before heading using the NDVI of the best fit had higher $r^2$ (>10\%)$ than those using common broad- band NDVI red or NDVI green. The models with the narrow-band NDVI of the best fit overcame broad- band NDVI saturation at high LAI values as frequently reported. Models using NDVIs of the best fit at booting showed higher predictive capacity for yield and yield component than models using crop variables.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.4
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• pp.353-358
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• 1994

Grain yields of errect-leaved corn hybrids were reported to be increased as planting density(PD) increased compared to those of horizontal leaf type hybrids. This trial was conducted to investigate the difference between errect and horizontal-leaved hybrids in response to different PD. Grain yields of both type hybrids were decreased at the highest PD, however, that of horizontal-leaved hybrid, Ga209 ${\times}$ Ki14A, was decreased more than errect-leaved hybrids which indicated varietal difference in response to PD. Responses to PD for days to tasseling, plant height, ear height, and leaf angle were not significant, also, PD ${\times}$ hybrid interactions were not observed. Yield components were decreased as PD increased and there were no PD ${\times}$ hybrid interactions for these characters. Leaf angle was negatively correlated with grain yield and yield components except for kernel weight.

• Plant Resources
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• v.5 no.2
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• pp.104-108
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• 2002

In order to obtain basic information for selecting early maturing rice varieties which is suitable for early cropping before Alisma plantago in the southern part of Korea. Six rice varieties were grown from May to August in 2002 at Youngjeon Experiment Field, Sunchon and yield components and yield of plants were investingated. Early maturing rice cv. Grubyeo showed higher rough rice yield than any other varieties used in the experiment. It showed high yield components, such as culm length, panicle length, number of panicles per plant, number of spikelets per panicle and ratio of ripened grains. Therefore, it was concluded that Grubyeo was the most suitable variety with high yield for the cultivation before growing of Alisma plantago at the southern part of Korea. The heritability of culm length number of spikelets per panicle and rough rice yield were high and that of panicle length number of panicle per plant, ratio of ripened grain and 1,000 grain wt. of milled rice were low. According to the result of path coefficient analysis, characters highly correlated with rough rice yield showed large direct effects on rough rice yield.

• Korean Journal of Materials Research
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• v.19 no.11
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• pp.619-624
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• 2009

Titanium alloys have been attractive due to a high ratio of strength to weight as well as good corrosion resistance. However, strengthening causes a decrease in ductility in Ti alloys, as is usual in other alloys. For enhanced strength without ductility reduction, grain refinement and tensile properties were investigated as functions of thickness reduction of cold rolling and annealing condition in Ti-15V-3Cr-3Sn-3Al alloy with a ${\beta}$ single phase. The average grain size of the specimen, which was cold-rolled by 90% and annealed at 700$^{\circ}C$ for 5 min, was decreased to approximately 19 ${\mu}m$. The grain refinement of 63 μm to 19 ${\mu}m$ increased yield stress by 90 MPa without a significant decrease in total elongation. The Ti-15-3 alloy exhibited very low work hardening during tensile test at a crosshead speed of 2 mm/min. This result was discussed based on dynamic recovery associated with dislocation annihilation in grain boundaries.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.216-223
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• 2003

This study was conducted to investigate the varietal differences in leaf senescence and the relationship between leaf senescence and photosynthesis during ripening stage of rice. During grain filling period, leaf senescence was evaluated by SPAD readings (an indirect indicator of chlorophyll content) for 3 rice varieties (SNU-SG1, Hwaseongbyeo, Nampungbyeo). SPAD value of flag leaf and 2nd leaf of SNU-SG1 were much higher than the other varieties and the leaves of SNU-SG1 also showed a tendency of delayed senescence as compared to the other varieties. Photosynthesis at light saturation (Pmax) of flag, 2nd and 3rd leaf in SNU-SG1 during grain filling period were much higher than Hwaseongbyeo and Nampungbyeo. The Pmax of the flag leaf in SNU-SG1 was especially higher over 20% than the other varieties. It was due to its higher mesophyll conductance and stomatal conductance as compared to the other varieties. Pmax, stomatal conductance and mesophyll conductance had positive correlation with SPAD value and nitrogen concentration of leaves. In conclusion, the stay green characteristics of SNU-SG1 would contribute to increasing the grain yield through the improved photosynthesis during grain filling.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.264-273
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• 2020

'Ilpum', a Korean short-grain mid-late maturing rice cultivar, was developed in 1990, more than 30 years ago. Despite its age, it has been the most widely grown cultivar in the Gyeongbuk province of South Korea for more than 25 years, making it the most important rice cultivar for the people of the Gyeongbuk province. The aim of this study was to analyze the relationship between the rice yield of "Ilpum', the main rice cultivar in the Gyeongbuk province, and climate elements in the Daegu (southern plain area) and the Andong (inland mountainous area) regions in Gyeongbuk, South Korea. The rice yield over the past five years increased by about 13% and 24%, compared to that produced in the late 1990s in Daegu and the early 2000s in the Andong region, respectively. The number of panicles per hill and the grain ripening rate significantly affected rice yield in the 'Ilpum' cultivars in the Daegu region. The faster heading was a factor in the increase in 'Ilpum' rice yield in the Andong region. The air temperature has been rising and sunshine duration has been increasing from the late 1990s to present in both regions. Rice yield was evaluated to understand the effect of climate factors. The rice yields increased owing to the long sunshine duration during the grain-filling stage in both regions. In Andong, increasing the maximum temperature during the vegetative stage increased rice yield. Rising air temperature during the reproductive stage also increased rice yield. In particular, long sunshine hours throughout the whole rice growing period increased the rice yield of this cultivar in the Andong region.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.4
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• pp.326-333
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• 2003

Transgenic rice plants expressing a Bacillus subtilis protoporphyrinogen oxidase (Protox), the last shared enzyme of the porphyrin pathway in the expressed cytoplasm or the plastids, were compared with non-trangenic rice plants in their growth characteristics such as tiller number, plant height, biomass, and yield. Transgenic rice plants of $\textrm{T}_3$ generation had 8 to 15 % and 25 to 43% increases in tiller number compared to non-transgenic rice plants at 4 and 8 weeks after transplanting(WAT); similar values were observed for $\textrm{T}_4$ generation at 4 and 8 WAT. However, the plant height in both $\textrm{T}_3$ and $\textrm{T}_4$ generations was similar between transgenic rice plants and non-transgenic rice plants at 4 and 8 WAT. Transgenic rice plants had 13 to 32% increase in above-ground biomass and 9 to 28% increase in grain yield compared to non-transgenic rice plants, demonstrating that biomass and yield correlate with each other. The increased grain yield of the transgenic rice plants was closely associated with the increased panicle number per plant. The percent of filled grain, thousand grains and spikelet number per panicle were similar between transgenic and non-transgenic rice plants. Generally, the growth and yield of transgenic generations ($\textrm{T}_2$, $\textrm{T}_3$, and $\textrm{T}_4$) and gene expressing sites (cytoplasm-expressed and plastid-targeted transgenic rice plants) were similar, although they slightly varied with generations as well as with gene expressing sites. The transgenic rice plants had promotive effects, indicating that regulation of the porphyrin pathway by expression of B. subtilis Protox in rice influences plant growth and yield.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.752-761
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• 2011

Recently, upland crops cultivation instead of paddy crops are more popular and highlighted by increase of social demand in agricultural land use. Especially, wheat cultivation for replacing of import food grain are more interested by government, and it is urgently needed that possibility of wheat cultivation is evaluated in the reclaimed tidal land. Crop cultivation is closely related with soil salinity and cultivation method in the reclaimed tidal land. In order to evaluate possibility of wheat cultivation, effect of different application level of compost and nitrogen additional fertilizer, also soil salinity on the grain yield and yield components of three wheat cultivars was studied at the newly reclaimed Saemangeum and Hwanong tidal lands in Korea. $270-300kg\;10a^{-1}$ of grain yield were obtained at the experimental site in the Saemangeum reclaimed tidal land where soil salinity was less than $4dS\;m^{-1}$ during growing periods from December, 2009 to June, 2010. However, almost no grain yield was obtained at the experimental site in the Hwaong reclaimed tidal land, where soil salinity was more than average $8dS\;m^{-1}$ ranged from 2.0 to $25.9dS\;m^{-1}$ during growing period and then salt demage was severe. Yield was significantly different among application level of compost and nitrogen additional fertilizer in the newly reclaimed Saemangeum tidal land. However, it is considered that three cultivars such as Chopum, Chogyung and Geumgang, have similar sensibility to soil salinity and fertilizer level, because there is statistically no difference among ciltivars in Hwaong and Saemangeum, and also among cultivars in the different levels of compost and fertilizer. Finally, it is concluded that wheat can be possibly produced by reasonable fertilizer application in the Saemangeum reclaimed tidal land, but wheat cultivation is impossible because of high soil salinity in the Hwaong reclaimed tidal land.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.554-559
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• 1993

This experiment was carried out at Chuncheon substation, Crop Experiment Station to investigate the effect of cold water irrigation on the growth and grain yield of rice in 1990. Irrigation of cold water (17$^{\circ}C$) delayed 10 to 19 days of heading, and reduced about 17 to 31% of plant height in terms of culm and panicle length. Number of panicle per plant was decreased and / or increased by cold water irrigation. Cold water irrigation reduced spikelet number per panicle and percent of filled grain. Grain yield was increased but, straw weight was decreased according to water temperature gradient from inlet to outlet. There was varietal differences in head rice recovery by cold water treatment. In general the dark brown and / or black colored kernel increased at cold water inlet but decreased percent of green kernel. Alkali digestible value increased and amylose content decreased at cold water inlet.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.4
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• pp.390-395
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• 1989

This experiment was conducted to study the effect of different defoliation methods on the same leaf characters and grain yields of perilla. Transplanting dates were from June 20, July 20, to August 20, 1989, and defoliated 30, 40, 50, 60 days after transplanting, respectively. The results obtained are summerized as follows: In the case that the fully developed leaves were defoliated, the number of total leaves were increased by more defoliations and by the later defoliation, Leaf length, width and area, fresh leaf weight, defoliated leaves per plant and grain yeidls were significantly influenced by the defoliation methods, Grain yields of the defoliation plots were lower than that of non-defoliation plot, As the above results, considering the grain yield, defoliation may be available in the case of one or two times of defoliation at the early growing stage. The profits from any type of defoliation were higher than that for grain yield only.