• BMB Reports
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• v.36 no.6
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• pp.597-602
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• 2003

Acid phosphatases (APases) play a role in the release of phosphate in organic complexes in soil. We investigated tissue- and isoform-specific responses of APases to phosphorus (P) deficiency in three rice genotypes; Dasan-byeo, Sobi-byeo, and Palawan. The levels of shoot APase activity per protein were similar in the three genotypes. They significantly decreased with P deprivation that was longer than seven days. Root APase activity per protein was two- to three-fold higher in Dasan than in Sobi and Palawan. In all genotypes the APase activity increased in P-deficient plants, but the increase was higher in Sobi and Palawan. After 21 days of P deprivation, secreted APase activity increased more than eight-fold in Dasan and two-fold in Sobi and Palawan. Isoform profiles of shoot and root APases were most diverse in Dasan. The activities of the major isoforms in P-deficient shoots decreased in all three genotypes. Depending on the genotypes, further increases in constitutive isoforms and new induction of one to four isoforms occurred in P-deficient roots. The results indicate that tissue and genotype differences in the response of APase to P deficiency are primarily facilitated by the different responses of the isoforms.

• Research in Plant Disease
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• v.23 no.2
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• pp.89-98
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• 2017

Ralstonia solanacearum species complex (RSSC) causes bacterial wilt, and it is one of the most important soil-borne plant pathogenic bacteria. RSSC has a large host range of more than 50 botanical families, which represent more than 200 plant species, including tomato. It is difficult to control bacterial wilt due to following reasons: the bacterial wilt pathogen can grow inside the plant tissue, and it can also survive in soil for a long period; moreover, it has a wide host range and biological diversity. In most previous studies, scientists have focused on developing biological control agents, such as antagonistic microorganisms and botanical materials. However, biocontrol attempts are not successful. Plant-derived metabolites and extracts have been promising candidates to environmentally friendly control bacterial wilt diseases. Therefore, we review the plant extracts, essential oils, and secondary metabolites that show potent in vivo antibacterial activities (in potted plants or in field) against tomato bacterial wilt, which is caused by RSSC.

• The Korean Journal of Pesticide Science
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• v.15 no.1
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• pp.55-60
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• 2011

To work out quality control methods of environmental-friendly organic materials (EFOMs), the reason and basis for EFOM-selection and farmer's favorite formulation type of EFOMs, etc were investigated on farmers who had been practicing environmental-friendly agriculture. EFOMs used were soil amendments, control agents of plant diseases and insect pests, plant growth promotion formulations, in turns. In EFOMs application time, 22.7% of farmers sprayed EFOMs without delay after they were bought, in other hand, 77.3% of farmers used EFOMs which had been bought and stored for some period. Microbial density on seventeen environmental-friendly microbial formulates (EFMFs) including microbial pesticides, a microbial fertilizer, and environmental-friendly organic materials was investigated at different storing temperature and shelf life. When the microbial density of EFMFs was investigated without delay after they were bought, all used microbial pesticides and a microbial fertilizer was confirmed to be optimal for the certified density but two of environmental-friendly organic materials was confirmed not to be optimal. When microbial density of 17 EFMFs were investigated after storing them for six months at $4^{\circ}C$, only one of 9 microbial pesticides was confirmed not to be optimal, the other hand four of seven environmental-friendly organic materials not to be optimal, which each of their microbial density was less than the certified density. Population dynamics of microbial agents was much more influenced in fluctuated temperature (room temperature) than in static temperature condition ($5^{\circ}C$ and $25^{\circ}C$). Shelf life of microbial agents according to microbial formulation type were high in granule type, liquid wettable type and liquid type in turns.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.5
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• pp.290-303
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• 2003

Modern agriculture has been heavily dependent on chemical fertilizers to meet the food demands of ever increasing population. Progressive depletion of major plant nutrients in soil due to intensive cultivation practices has also necessitated the use of higher dose of chemical fertilizers particularly in soils where the organic matter content is very low. Indiscriminate use of chemical fertilizers and pressure on agriculturists to enhance per area crop yields has led to fast depletion of fossil fuel resources with concomitant increase in the prices of chemical fertilizers and also led to environmental pollution. Hence, the current trend throughout the world is to explore the possibility of using alternate nutrient sources or increasing the efficiency of chemical fertilizers by supplementing them with organic fertilizers and bioinoculants comprising largely microbes like, bacteria, fungi, algae etc to enhance nitrogen and phosphates in the soil thus creating a sustainable agricultural environment. Among the different microbial inoculants or biofertilizers, Azospirillum could be a potential candidate due to its non specific host root colonization. It had the capability to fix $N_2$ in wide pH regimes and even in presence of combined nitrogen. Azospirillum inoculation can increase the crop yield to 10-25% and substitute 25% of recommended doses of nitrogenous fertilizers. Apart from nitrogen fixation, Azospirillum is also involved in the root improvement, the activity which was attributed to an increase in the rate of water and mineral uptake by roots. The ability of Azospirillum to produce phytohormones was reported to enhance the root respiration rate, metabolism and root proliferation. They have also been reported to produce polyhydroxybutyrate, that can be used as a biodegradable thermosplastic. A lot of studies have addressed improvements in enhancing its efficiency to fix nitrogen fixation and hormone production.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.246-250
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• 2003

In order to preserve the soundness of agro-ecosystem and products safety in agriculture, this study was evaluated environmental impact in relation to the INM (Integrated Nutrient Management) and IPM (Integrated Pest Management) at paddy fields at Ok-Chun and Yang-Pyung region. By introduction of INM with the application of BB(bulk-blanded) fertilizer based on soil analysis and IPM, the application rate of fertilizer was reduced to about $28.6{\sim}39.4%$ and the yield of brown rice was increased to about $3{\sim}10%$ compared to conventional practices. The concentrations of COD, $NH_4-N$, and $NO_3-N$ in irrigation water flowed to the environmental-friendly agriculture practices were 15.0, 0.67, and 1.39 mg/L, respectively. The concentrations of COD, $NH_4-N$, and $NO_3-N$ from paddy fields in drainage water were 12.4, 0.29, and 2.42 mg/L, respectively. The total number of the freshwater invertebrates was higher in field treated with fertilization by prescription with soil testing. Also, the population density of aquatic insects was higher than the other fields at both demonstration villages. In conclusion, it was possible to reduce the amount of fertilizer and agricultural chemicals application, and increase the yield of rice by application of the environmental-friendly agriculture practices.

• Korean Journal of Environmental Agriculture
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• v.38 no.2
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• pp.76-82
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• 2019

BACKGROUND: For sustainable agriculture, there are various agricultural practices including low input. Over the last few decades high input of chemical fertilizer and compounds results in environmental pollution and deterioration of soil fertility. Soybean (Glycine max L.) is well known eco-friendly crop due to their symbionts. Soybean has a relationship with nitrogen fixation bacteria called rhizobia. In this research work, we investigated effects of soybean cultivation on soil microorganism activities. METHODS AND RESULTS: Experiments were conducted in pots and potato cultivation was used as reference. Soil chemical properties were analyzed considering soil nutrient over cropping period. For the soil microbial community analysis, dehydrogenase activity analysis (DHA) analyzed along with denaturing gradient gel electrophoresis. The results showed that higher soil organic matter in the soybean cultivation soil than in the potato cultivation soil. Available $P_2O_5$ concentration increased gradually in both pots but showed higher value in the potato cultivation soil. DHA value implying microbial activities showed higher value in the soybean cultivation soil over all cropping period. CONCLUSION: The cause of high microbial activity in the soybean cultivation soil was considered to the effects of some specific microorganisms related to soybean cultivation. Therefore, the availability of soybean cultivation for sustainable agriculture should be encouraged in terms of microorganism community activity in soil.

• Korean Journal of Environmental Agriculture
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• v.24 no.2
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• pp.191-197
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• 2005

Green house soils have been intensively cultivated with excessive application of compost and chemical fertilizer for vegetable growth. The objective of this study was to establish the reasonable fertilizer application system for rice cultivation in green house soil. Field experiment was carried out with rice cv. Geumo-byeo 1 in Jisan series soil (fine loamy, mixed, mesic family of Fluventic Haplaquepts) that was previously cropped with green pepper (Capsicum annuum L.) for the last 3 years. Treatment consisted of conventional fertilization $(N-P_2O_5-K_2O=11-4.5-5.7kg\;10a^{-1})$, no basal fertilization, 50% reduction of basal fertilization no top dressing, bulk blending fertilizer, and no fertilizer. The value of pH, available phosphate, and exchangeable potassium after experiment was lower than those before experiment while organic matter content was not difference in all treatment. The value of salt elusion was the highest in no basal fertilization plot. The amount of $NH_4-N$ in soil was higher in growth stage of rice as fertilizer amount increased in 1998. The changes of plant height and tiller were higher as fertilizer amount increased. Thousand-grain weight as yield component was higher in no basal fertilization plot all the year because of decreasing panicle. There was no significant difference in rice yield between treatments in 1998. However, conventional fertilization resulted in significantly increased rice yield in 1999. Nitrogen use efficiency was the highest in no basal fertilization plot in 1998 and in conventional fertilization plot in 1998. Our results suggest that no basal fertilization be best to increase salt elusion with slightly increased yield in first year for rice cropping after vegetable harvesting, which method improves fertilization efficiency. However, conventional fertilization was good for second rice cropping after vegetable harvesting in greenhouse.

• Korean Journal of Environmental Agriculture
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• v.27 no.2
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• pp.163-170
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• 2008

This experiment was conducted to determine the development of mixed organic fertilizer using photosynthetic bacteria and mass production of mixed microbial compound for the environment-friendly agriculture. Photosynthetic bacteria, Rhodobacter sp. SA16 was isolated from soil collected by plastic film house. The SA16 strain was identified based on 16S rDNA sequence analysis and it is closely related to Rhodobacter sp.(100% similarity). The mixed organic fertilizer using SA16 was made of $N-P_2O_5-K_2O=60-10-20\;g\;kg^{-1}$ with combined soybean cake, sesame cake, powdered blood, fish meal, powdered bones and red-yellow soil. The mixed organic fertilizer 0.45, 0.90 and 1.35 Mg $ha^{-1}$ application in Ihyeon series was treated based on soil testing for lettuce cultivation in plastic film house. These results showed that the yield was increased the 18 and 19%over control by the mixed organic fertilizer application 0.45 and 0.90 Mg $ha^{-1}$, respectively. In the physical properties of the soil, the porosity of mixed organic fertilizer 1.35 Mg $ha^{-1}$ treatment was highest at 58.8%. Our results clearly revealed that the organic fertilizer using Rhodobacter sp. SA16 and mass production of mixed strains could be a useful technology in pursuing environment-friendly agriculture.

• The Plant Pathology Journal
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• v.28 no.3
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• pp.282-289
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• 2012

The root rot of pepper (Capsicum annuum L.) caused by Phytophthora capsici is one of the most important diseases affecting this crop worldwide. This work presents the evaluation of the capacity of Streptomyces griseus H7602 to protect pepper plants against Phytophthora capsici and establishes its role as a biocontrol agent. In this study, we isolated an actinomycete strain H7602 from rhizosphere soil, identified it as Streptomyces griseus by 16S rRNA analysis and demonstrated its antifungal activity against various plant pathogens including P. capsici. H7602 produced lytic emzymes such as chitinase, ${\beta}$-1,3-glucanase, lipase and protease. In addition, crude extract from H7602 also exhibited destructive activity toward P. capsici hyphae. In the pot trial, results showed the protective effect of H7602 against pepper from P. capsici. Application of H7602 culture suspension reduced 47.35% of root mortality and enhanced growth of pepper plants for 56.37% in fresh root and 17.56% g in fresh shoot as compared to control, resulting in greater protection to pepper plants against P. capsici infestation. Additionally, the enzymatic activities, chitinase and ${\beta}$-1,3-glucanase, were higher in rhizosphere soil and roots of pepper plants treated with H7602 than other treated plants. Therefore, our results indicated a clear potential of S. griseus H7602 to be used for biocontrol of root rot disease caused by P. capsici in pepper.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.228-234
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• 2004

In organic farming, nutrients for the crop production are mostly supplied by compost containing various organic materials. The long-term organic cultivation would result in continuous changes of soil chemical properties and fertility. The aim of this study was to investigate the contribution of long-term organic cultivation to the soil fertility in Korea focusing on the chemical properties of soil. Soil samples were collected from organic farms that had been cultivated for 8-10 years after certification of organic product through the conversion periods of 2-3 years. Thereby each organic farm had acquired optimal cultivating techniques and soil condition. We separated organic farms into three groups by cultivating crops, i.e. leaf vegetables, fruit vegetables and fruit trees. In each group, five representative farms were chosen in order to investigate the relationships between application rate of compost and nutrient contents in soil. The application rate of compost was approximately $10-15Mg\;10a^{-1}$ for the first 2-3 years at the beginning of organic farming and then reduced to a rate of $3-4Mg\;10a^{-1}$ after stabilization of organic matter content in soil with $30-50g\;10a^{-1}$. However, the continuous organic farming for 8-10 years resulted in accumulation of nutrients, especially of P, in soil probably due to the excessive amounts of compost applied. In conclusion, we suggest that the application rate and organic sources of compost should be decided on the basis of P content in soil by soil testing and thereafter the lack of soil N content for crop cultivation should be compensated by crop rotation with such as legumes. This might be an approach to the original meaning of organic farming as an environmental friendly agriculture.