• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.2
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• pp.73-80
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• 2023

This study was conducted to analyze changes of irrigation water and soil volumetric water content by irrigation method of field soil in Saemangeum reclaimed tideland. The main test irrigation methods was surface drip irrigation, sprinkler irrigation, and sub drip irrigation. In addition, the correlation between irrigation amounts and crop yield by irrigation method was investigated. For soil volumetric water contents increases by 25%, surface drip irrigation took 1.5 hour, sprinkler irrigation took 2.0 hours, and sub drip irrigation took 3.0 hours. As a result of analyzing the irrigation amounts according to the yield, the surface drip irrigation was 2.66 mm/day in the seedling stages, 3.31 mm/day in the vegetative growth stages, and 5.09 mm/day in the flowering stages. Sprinkler irrigation was 2.90 mm/day in the seedling stages, 3.87 mm/day in the vegetative growth stages, and 7.11 mm/day in the flowering stages. Sub drip irrigation was 2.42 mm/day in the seedling stages, 3.09 mm/day in the vegetative growth stages, and 4.87 mm/day in the flowering stages. It was analyzed that there was a statistically significant difference in irrigation amounts by fresh weight and irrigation method (F=4.002, p=0.022), and irrigation amounts by dry weight and irrigation method (F=3.499 p=0.034). Surface drip irrigation was judged to be more appropriate than sprinkler irrigation or sub drip irrigation for field crops in Saemangeum reclaimed land.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.5
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• pp.282-287
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• 2000

Soybean [Glycine max (L.) Merrill] crops, grown in a rice soybean rotation, can suffer when grown in soil with excessive moisture. The objective of this work were to determine the reduction in growth and yield, responses of vegetative and reproductive growth of soybean to excessive soil moisture achieved by prolonged irrigation. Responses of different cultivars were determined at growth stages from V6 to R8 to clarify the sensitive growth stages or characteristics to excessive soil moisture. Cultivar differences in response to excessive soil moisture condition were conspicuous in seed dry weight and harvest index (HI) but not in the response of seed number or pod number per plant. The timing of irrigation causing the condition of excessive soil moisture influenced the vegetative or reproductive traits. Soybean plants were more affected by irrigation commencing at the pre-flowering than at the post-flowering stage. Post-flowering irrigation did not reduce growth of vegetative organs significantly; in fact the growth of stems and leaves was facilitated by the prolonged irrigation commencing at flowering. Differences between cultivar response to prolonged irrigation were assumed to relate to the reduced amount of assimilates translocated to the reproductive organ.

• Preventive Nutrition and Food Science
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• v.12 no.4
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• pp.259-266
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• 2007

It has been proposed that the mode of action of nisin against vegetative cells and spores of Clostridium botulinum is different. However, clear explanation is not available. Therefore, nisin action against vegetative cells and spores of C. botulinum was investigated in this study. Nisin was added at various stages of spore-to-vegetative cell transition and changes to sensitivity to the bacteriocin were observed. Different nisin preparation (Nisaplin or pure nisin) was compared for their activity against different stages of spore transformation of C. botulinum ATCC 25763. Germination was measured by determining loss of heat resistance and observing phase darkening of spores under phase-contrast microscope. Nisin acted bactericidally against vegetative cells, but acted sporostatically against spores of C. botulinum under the same concentration. This bactericidal and sporostatic action of nisin was dependent on the concentration of nisin used. Presence of nisin during spore activation by heat increased subsequent phase darkening and germination rates. However, nisin inhibited the germination and the outgrowth, when it was added after heat activation stage. Findings from this study suggest that the time of addition of nisin is very important for the effective control of spores during the heating process of foods. In addition, it may be possible to apply nisin at the stage of processing that coincides with the most sensitive stage of spore transformation.

• Journal of Plant Biology
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• v.22 no.3
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• pp.81-84
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• 1979

Catalase, glycolate oxidase, hydroxypyruvate and NADPH-glyoxylate reductases activities in cell free extracts from leaves of 3 cultivars, Suwon 264, IR 36 and Jin Heung of rice plants were studied at different growing stages. Catalase and glycolate oxidase shows inclining activities toward the maximum vegetative growth whereas declining activities in either the enzymes were noticed during the maturing stage. After the photoperiodic condition exhibit increasing hydroxypyruvate and NADPH-glyoxylate reductases activities with time until maturing stage. No significant differences were found in the enzyme activities, and in analytical data of nitrogen, chlorophyll contents, dry weight and soluble proteins among the 3 cultivars.

• Korean Journal of Remote Sensing
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• v.37 no.4
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• pp.699-717
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• 2021

South Korea is pushing for the advancement of crop production technology to achieve food self-sufficiency and meet the demand for safe food. A medium-sized satellite for agriculture is being launched in 2023 with the aim of collecting and providing information on agriculture, not only in Korea but also in neighboring countries. The satellite is to be equipped with various sensors, though reference data for ground information are lacking. Hyperspectral remote sensing combined with 1st derivative is an efficient tool for the identification of agricultural crops. In our study, we develop a system for hyperspectral analysis of the ground-based reflectance spectrum, which is monitored seven times during the cultivation period of three soybean crops using a PSR-2500 hyperspectral sensor. In the reflection spectrum of soybean canopy, wavelength variations correspond with stages of soybean growths. The spectral reflection characteristics of soybeans can be divided according to growth into the vegetative (V)stage and the reproductive (R)stage. As a result of the first derivative analysis of the spectral reflection characteristics, it is possible to identify the characteristics of each wavelength band. Using our developed monitoring system, we observed that the near-infrared (NIR) variation was largest during the vegetative (V1-V3) stage, followed by a similar variation pattern in the order of red-edge and visible. In the reproductive stage (R1-R8), the effect of the shape and color of the soybean leaf was reflected, and the pattern is different from that in the vegetative (V) stage. At the R1 to R6 stages, the variation in NIR was the largest, and red-edge and green showed similar variation patterns, but red showed little change. In particular, the reflectance characteristics of the R1 stage provides information that could help us distinguish between the three varieties of soybean that were studied. In the R7-R8 stage, close to the harvest period, the red-edge and NIR variation patterns and the visible variation patterns changed. These results are interpreted as a result of the large effects of pigments such as chlorophyll for each of the three soybean varieties, as well as from the formation and color of the leaf and stem. The results obtained in this study provide useful information that helps us to determine the wavelength width and range of the optimal band for monitoring and acquiring vegetation information on crops using satellites and unmanned aerial vehicles (UAVs)

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.2
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• pp.88-92
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• 2000

Excessive soil water in paddy field induces growth losses during the vegetative stages of soybean plants. Our objectives were to know growth responses of soybean as affected by the level of ridge heights. A field experiment was conducted at the Research Farm of Korea University near Seoul in 1996. Ten cultivars of soybean (Glycine max (L.) Merrill) were planted at the ridge heights of 10, 30, and 50cm in paddy soil on 27 June. Total dry matter accumulation at the 10cm ridge height was severely decreased until the growth stage of R5 as compared to the ridge heights of 30 and 50cm, and this decrement was mainly due to both reduced leaf and stem dry weights. However, seed dry weight was not significantly decreased at the lower ridge height with the increment of harvest index. Cultivar differences were found on seed dry weight, crop growth rate from R1 to R5, and leaf/stem ratio of R5. From the above results, soybean growth responses to excessive soil water in paddy field were different between seed filling stage and late vegetative to early reproductive growth stages.

• Asian-Australasian Journal of Animal Sciences
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• v.2 no.1
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• pp.27-34
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• 1989

Different fractions of maize plant and whole mixed fodder were analysed for their chemical composition and dry matter digestibility (DMD). Highest crude protein (CP) values were found in leaves as compared to the other portions. Younger plants contained more CP as compared to the matured ones. The crude fiber (CF) content of various fractions of the plant ranged between 19.12 to 35.60% with maximum values in the bottom portion of the stem. Matured plants contained more CF. The analysis of cell wall constituents indicated that the maximum values for neutral detergent fiber (NDF) were found in the bottom portion and in the whole mixed plant. The highest levels of acid detergent fiber (ADF) were observed in bottom fraction followed by whole mixed plant, whereas the other plant fractions did not show any differences. Variation in acid detergent lignin (ADL) values existed in different fractions of the plant and the lowest were in the top portion of the stem. Although there existed a variation in the mineral composition of different fractions of the plants, the results were non significant. Maximum DMD was found in leaves followed by the whole mixed plant, middle and bottom portion of the stem. The values of DMD were higher in younger plants as compared to the matured ones. It may be concluded that younger plants and the upper portion of the plants have a higher nutritive value as compared to the matured plants and lower portion of the plants.

• Korean Journal of Microbiology
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• v.16 no.4
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• pp.148-154
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• 1978

Saccharomyces cerevisiae J170, a mutant, was used for $DL-^{14}C-leucine$ uptake during the sporulation and vegetative stage. $^{14}C-Leucine$ uptake into yeast cells appeared the highest at pH 6.0, indicating the same result of glucose transport, $^{14}C-Leucine$ uptake in sporulation period was higher than in growth phase, showing the evidence that leucine is more required for protein synthesis. This tendency has the evidence tht leucine is more required for protein synthesis. This tendency has the evidence that leucine is more required for protein synthesis. This tendency has been also supported from the result of Km values of leucine uptake in two stages of yeast. Leucine uptake was inhibited by 2,4-dinitrophenol in two stages of yeast. This means that leucine transport system is associated with energy dependent in both stages. The contents of all amino acid in growth phase cells were higher than those of sporulation stge cells, and those of methionine and tyrosine were showed in trace during the sporulation stage. In contrast, the content of glutamic acid in sporulation stage was compared with those of other amino acids.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.295-303
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• 1990

In this study, drought period when important agronomic characters of sesame plant is critical, was examined at different growth stages. Plant death by drought started at 40 days after drought in vegetative growth stage and 20 days, in reproductive growth stage. Obserbed by growth stage, drought damage in reproductive growth stage was more in jurious than vegetative growth stage. All the important agronomic characters was refreshed until 40 days and 20 days after drought in vegetative growth stage and reproductive growth stage respectively, but it could berefreshed after those times. Decrease rate of yield by drought ranged from 29 to 80% in vegetative growth stage and from 49 to 85% in respective growth stage. All the important agronomic characters except rate of ripeness showed positive association with grain yield under drought condition. Oil content in grain was decreaced by drought but composition of fatty acid was not affected by it.

• Journal of Crop Science and Biotechnology
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• v.10 no.4
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• pp.281-286
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• 2007

Gibberellins are growth hormones that play a pivotal role in the growth and development of plants. Present investigations were carried to check the effect of nitrogen(N) and silicon(Si) on bioactive $GA_1$ and its immediate precursor $GA_{20}$ at different growth stages of two rice cultivars with different maturity traits. It was observed that the endogenous bioactive $GA_1$ level gradually increased during vegetative stage and anthesis stage of both Junghwabyeo(early flowering cultivar) and Daesanbyeo(late flowering cultivar). However, the $GA_1$ and $GA_{20}$ content start decreasing during the seed filling stage in both rice cultivars, which indicated a possible relationship of bioactive $GA_1$ and floral development. Our results also confirmed that early 13-hydroxylation pathway was operated at all developmental stages of rice plant. Variation in the levels of the endogenous gibberellins in rice shoots were measured by GCMS-SIM using $^2H_2$-labeled gibberellins as internal standards. Combined application of N and Si enhanced growth parameters and reduced lodging index of both rice cultivars. It was thus concluded that the level of physiologically active $GA_1$ increased during vegetative and early reproductive stage, but starts declining at seed filling stage.