• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.3
• /
• pp.213-221
• /
• 2007

In response to anthropogenic global warming due to a buildup greenhouse gas, the effect of the air temperature on water temperature has been noticed and some efforts have been made to build an air/water temperature relationship at the Masan Bay area by the Ministry of Maritime Affairs & Fisheries (MOMAF). As a result of analyzing the auto- and cross-correlation coefficient between air/water temperature, high correlation $(\sim0.9)$ is shown and the correlation coefficient of air temperature is higher than that of water temperature at the lag time less than approximately 10 days. Separate functions are fitted to the air/water relationship at the Masan Bay to take hysteresis into account. The slopes of the straight line for the rising limb are 0.829 and 0.774 for MA1 and MA2 station respectively, while 1.385 and 1.444 ($\sim1.75$ times larger) for the falling limb. Consequently, the seasonal hysteresis should be considered in order to determine an air/water relationship and accurately estimate the water temperature using the air temperature at Masan Bay.

• Asian-Australasian Journal of Animal Sciences
• /
• v.17 no.3
• /
• pp.349-354
• /
• 2004

The effects of probiotic-vitacogen and galacto-oligosaccharides (GOS) supplementation on methanogesis, energy and nitrogen utilization in replacement dairy cows were evaluated. A basal diet comprising orchardgrass hay, lucerne hay cube and concentrate (2:2:1, DM basis) were fed with or without supplements to four cows at $80g\;DM/kgBW^{0.75}$per day in a $4{\times}4$ Latin square arrangement. The four treatments were; 1) basal diet, 2) basal diet plus 100 g probiotic-vitacogen, 3) basal diet plus 50 g GOS, 4) basal diet plus 50 g GOS and 100 g probiotic-vitacogen. Nutrient apparent digestibility was not altered by the effect of supplementation. Nitrogen intake was significantly (p<0.001) higher for the two vitacogen-supplemented diets compared to control and GOS supplemented diets. However, vitacogen supplemented diets had numerically higher fecal and urinary nitrogen losses, thereby, having lower nitrogen retention compared to control and GOS supplemented diets. Gross energy intake was also significantly (p<0.05) higher for vitacogen-supplemented diets compared to control and GOS diets, however, due to higher losses in feces, urine, methane and heat, GOS supplemented diet had numerically higher energy retention. There was an 11% reduction in methane emission (liters/day) in GOS supplemented diet compared to control diet. However, the combination of GOS with vitacogen resulted in an increased methane emission. When expressed per unit of animal production (g/kg live-weight gain), methane production tended to be lower in vitacogensupplemented diets compared to control and GOS diets. The supplementation of replacement dairy cows with GOS reduced methane emission (liters/day), while, vitacogen supplementation reduced methane emission per unit animal production. The two feed supplements may contribute to the abatement of methane as a greenhouse gas.

• Korean Journal of Environmental Agriculture
• /
• v.35 no.1
• /
• pp.46-54
• /
• 2016

BACKGROUND: The tobacco whitefly(Bemisia tabaci Gennadius) and western flower thrips(Frankliniella occidentalis Pergande) seriously damaged to several greenhouse crops and transmitted plant viruses such as the Tomato Yellow Leaf Curl Virus(TYLCV) and Tomato Spotted Wilt Virus(TSWV). Objective of this study was to elucidate exclusion effects of insect screen nets by various hole sizes and colors for control of the two insect pests in controlled environments such as a closed plant production system.METHODS AND RESULTS: The exclusion effects to various hole sizes of three other colors with 30 individuals of two insect pests was evaluated. B. tabaci was not showed not difference to different colors and sizes. F. occidentalis showed that 0.2 mm black screen was the most effective exclusion than other colors of 0.6 and 0.8 mm.CONCLUSION: The two insects were different reponses to various hole sizes of white and other color screen nets. It was proved that the 0.4 mm white screen net used in this experimental condition was suitable for exclusion of B. tabaci and 0.2 mm black forF. occidentalis.

• The Korean Journal of Pesticide Science
• /
• v.2 no.1
• /
• pp.24-31
• /
• 1998

Chemical derivative synthesis of ricinine, an active compound of Ricinus communis which showed high mortality against brown planthopper (Nilaparvata lugens), was performed to improve its pesticidal activity and the toxicity of 12 synthetic derivatives against major insect pests and phytopathogenic fungi were examined. Carbamate derivatives of ricinine could be synthesized from the precursor of ricinine, chloronorricinine and norricinine, whereas the derivatives were not synthesized from chlororicinic acid and ricinic acid having ketone group of pyridine ring. In organophosphates, reaction with oxon type of phosphate gave better yield than thiono type. Among the organophosphate derivatives of ricinine, thiono type of derivative structure gave $96.3%{\sim}100%$ mortality of the brown planthopper and the two-spotted spider mite (Tetranychus urticae) at 500 ${\mu}g/ml$ level. On the other hand, carbamate derivatives did not show insecticidal activity. In the fungicidal activity of ricinine derivatives, the derivative having amino radical at the 2 position of ricinine gave 85 to 100% of mycelium growth inhibition effect against ten major plant pathogens at the 200 ${\mu}g/ml$ level. In particular, the control value of the derivative on the rice blast (Pyricularia grisea) and barley powdery mildew (Erysiphe graminis) at the 250 ${\mu}g/ml$ level in vivo under greenhouse conditions was 92% and 96%, respectively.

• The Korean Journal of Pesticide Science
• /
• v.14 no.1
• /
• pp.49-53
• /
• 2010

Disease control efficacy was evaluated with use of Bacillus subtilis KB-401 against cucumber powdery mildew in a greenhouse and fields. B. subtilis KB-401 showing inhibitory effect on mycelial growth of various phytopathogenic fungi was formulated for the evaluation. The formulated biofungicide of B. subtilis KB-401 was less effective at 1,000 times dilution rate than that at 250 or 500 times dilution rate. The powdery mildew was successfully controlled by the biofungicide at the early stage of disease development. The field performance of the biofungicde was conducted in Asan and Cheonan city. Three or four consecutive applications of the biofungicide at 500 dilution rate with 10-day intervals resulted in considerable efficacy of disease control as high as 83.3%.

• Korean Journal of Organic Agriculture
• /
• v.28 no.2
• /
• pp.235-250
• /
• 2020

Agricultural practices are known to have a crucial influence not only on soil physico-chemical properties but also on microbial communities. To investigate the effect of farming practices on soil microbial communities, a total of 10 soil samples were collected, including five conventional and five organic farming soils cultivated with peppers in plastic greenhouse. We conducted barcorded-pyrosequencing of V1-V3 regions of 16S rRNA genes to examine soil microbial communities of two different farming practices. Taxonomic classification of the microbial communities at the phylum level indicated that a total of 22 bacterial phyla were present across all samples. Among them, seven abundant phyla (>3%) including Proteobacteria, Actinobacteria, Firmicutes, Acidobacteria, Bacteroidetes, Chloroflexi, and Gemmatimonadetes were found, and Proteobacteria (33.0 ± 5.7%), Actinobacteria (19.9 ± 9.7%), and Firmicutes (13.6 ± 5.0%) comprised more than 66% of the relative abundance of the microbial communities. Organic farming soils showed higher relative abundances of Proteobacteria and Firmicutes, while Actinobacteria and Chloroflexi were more abundant in conventional farming soils. Notably, the genera Bacillus (higher in organic farming soils) and Streptomyces (higher in conventional farming soils) exhibited significant variation in relative abundance between organic and conventional farming soils. Finally, correlation analysis identified significant relationships (p<0.05) between soil chemical properties, in particular, pH and organic matter content and microbial communities. Taken together, this study demonstrated that the changes of soil physico-chemical properties by agricultural farming practices effected significantly (p<0.05) on soil microbial communities.

• Korean Journal of Weed Science
• /
• v.30 no.3
• /
• pp.215-224
• /
• 2010

A greenhouse experiment was conducted to determine the effects of medium components and shade treatment on the growth, contents of total phenolics and flavonoids, and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity of Youngia sonchifolia. Substrates combined with coco peat and perlite (ratio 70:30 or 50:50, v/v) showed higher plant length, leaf area, and fresh weight than single substrate (P<0.05). Shade treatment also significantly reduced plant height, root length, leaf areas, and fresh weight (P<0.05) with increasing of the degree. Shading treatment, however, increased contents of total phenolics [mg ferulic acid equivalents $kg^{-1}$ dry wt.] and total flavonoids [mg naringin equivalents $kg^{-1}$ dry wt.] in shoot parts of Y. sonchifoli, showing 110.2 to 119.2 and 128.3 to 146.7 mg $kg^{-1}$, respectively. The antioxidant potential of the methanol extracts from the plants dose-dependently increased DPPH free radical scavenging activity, and the activity was higher in shoots (50.2 to 80.8%) than in roots (47.7 to 49.8%), and in shading treatment than in no shade.

• Korean Journal of Environmental Agriculture
• /
• v.39 no.1
• /
• pp.65-74
• /
• 2020

BACKGROUND: Soil carbon sequestration has been investigated for a long time because of its potential to mitigate the greenhouse effect. No- or reduced tillage, crop rotations, or cover crops have been investigated and practiced to sequester carbon in soils but the roles of soil biota, particularly microorganisms, have been mostly ignored although they affect the amount and stability of soil organic matters. METHODS AND RESULTS: In this study we analyzed the organic matter and microbial community in organically cultivated corn field soils where no-tillage (NT) or conventional tillage (CT) had been practiced for about three years. The amounts of organic matter and recalcitrant carbon pool were 18.3 g/kg dry soil and 4.1 g C/kg dry soil, respectively in NT soils, while they were 12.4 and 2.5, respectively in CT soils. The amounts of RNA and DNA, and the copy numbers of bacterial 16S rRNA genes and fungal ITS sequences were higher in NT soils than in CT soils. No-tillage treatment increased the diversities of soil bacterial and fungal communities and clearly shifted the bacterial and fungal community structures. In NT soils the relative abundances of bacterial phyla known as copiotrophs, Betaproteobacteria and Bacteroidetes, increased while those known as oligotrophs, Acidobacteria and Verrucomicrobia, decreased compared to CT soils. The relative abundance of a fungal phylum, Glomeromycota, whose members are known as arbuscular mycorrhizal fungi, was about two time higher in NT soils than in CT soils, suggesting that the higher amount of organic matter in NT soils is related to its abundance. CONCLUSION: This study shows that no-tillage treatment greatly affects soil microbial abundance and community structure, which may affect the amount and stability of soil organic matter.

• Research in Plant Disease
• /
• v.14 no.3
• /
• pp.182-186
• /
• 2008

Recently organic farming practice of rice has been emerged in Korea, but one of the major limiting factor is the no effective environmental-friendly agro-materials to control major plant diseases. Bordeaux mixture has been used effectively as a preventive agro-chemical. The aim of this study was to investigate efficacy of Bordeanux mixture on control of rice blast caused by Magnaporthe grisea which is one of the disruptive rice diseases in world-wide. In greenhouse experiment, pre-treatment of 6-6 type of Bordeaux mixture before inoculation of spore suspension of M. grasea showed 71 % of control value. In field experiment, preventive applications of 4-8 and 6-6 types of Bordeaux mixture showed over 71 % of the control value. Chemical injury on rice leaves were not found in the application concentrations of all types of Bordeaux mixture, but observed in applications of Bordeaux mixtures between 30 and 100 diluted concentrations. This results indicate Bordeaux mixture can be used as an effective environmental-friendly agro-chemical to control rice blast disease in the field.

• Research in Plant Disease
• /
• v.23 no.2
• /
• pp.114-149
• /
• 2017

World-wide crop loss caused by insect pest and nematode reaches critical level. In Korea, similar crop loss has been gradually augmented in the field and greenhouse due to continuous crop rotation. The current methods on controlling herbivorous insects and plant parasitic nematodes are mostly depended on agro-chemicals that have resulted additional side-effect including occurrence of resistant insects and nematodes, environmental contamination, and accumulation in human body. To overcome the pitfalls, microbe-based control method have been introduced and applied for several decades. Here, we revised biological control using by the bacteria, fungi, and virus in order to kill insect and nematode and to attenuate its virulence mechanism. The introduced microbes mainly secreted out the hydrolysing enzymes and toxic compounds to target host membrane or cell wall directly. Indirectly, the microbe-triggered plant innate immunity against insects and nematodes was also reported. In conclusion, we provide a new frontier of microbe-based environmentally friendly procedure and effective methods to manage insects and nematodes.