• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.346-346
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• 2017

In Northern Laos, maize is cultivated in continuous cropping without fertilizer, fallowing nor any other soil conservation practice. It is expected that this inadequate management in maize cultivation will degrade soil and decrease yield. However, there is limited information about the change of soil condition and yield under continuous maize cultivation. We tried to evaluate the change of soil condition and yield under continuous maize cultivation in Northern Laos. Our study was conducted in farmer's flat and slope fields in Sainyabuli province where maize cultivation had been introduced earlier than the other provinces of Northern Laos. Our study was conducted in 21 fields in 2014, and in 19 fields in 2015. We analyzed grain yield and soil characteristic (total carbon (TC), total nitrogen (TN), available phosphorus (Av-P), exchangeable cation, pH, soil texture) at 3 places in each field. The 3 places were set at different elevation level (lower position, middle position, upper position) in slope fields. Further, the period of continuous maize cultivation and crop management practice were investigated. Then, by evaluating the relation between the period of continuous maize cultivation and yield and the soil characteristics, the effect of maize cultivation was estimated. Crop management practices were similar among the investigated fields. Maize was cultivated in rain season. Grain seed and cob were harvested on September or October, but shoot was left on the fields. No crop was cultivated during dry season. Fertilization and fallowing has never been conducted under continuous maize cultivation. On the other hand, the period of maize cultivation was different among the fields, and ranged from 2 years to 30 years. In the slope fields, as the period of continuous maize cultivation was longer, the contents of TC and TN were lower at all 3 positions, Av-P content was lower at the upper position, exchangeable potassium (Ex-K) content was lower at the middle and the upper positions. The other soil characteristics weren't related with the period of maize cultivation in the slope fields. In contrast, soil characteristics weren't related with the period of maize cultivation in the flat fields. Yield was lower as the period of maize cultivation was longer at the upper position of the slope fields. At middle position of slope fields, yield tended to be low with increase of the period of maize cultivation. In contrast, yield wasn't related with the period of continuous maize cultivation in flat fields. From the results about crop management, it was presumed that the period of maize cultivation was one of the main factors causing the difference of yield and soil characteristics among the fields. Therefore, from the result of yield and soil condition, it was considered that the continuous maize cultivation decreased soil productivity in the slope fields with decline of TC, TN, Av-P, Ex-K and yield at upper position of slope fields, and decline of TC and TN in the other positions in Sainyabuli province.

• Journal of Ginseng Research
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• v.19 no.2
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• pp.175-180
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• 1995

The disease development of root-rot [pathogen:Cylindrocarpon destruction (Zinssm.) Scholten] occurred in 2-year old ginseng (Panax ginseng C.A. Meyer) was investigated in the continuous (the first cultivation: 1978∼1982, 2nd cultivation: 1990∼1993 and abolished in 1993 due to replanting problem) and replanted cultivation (period of cultivation: 1980∼1984). In the continuous cultivation, incidences of root-rot were 0.7% on May 3, 48.6% on May 24, and 95.8% on June 14, respectively. In the replanted cultivation, no symptom was observed on May 3 and disease incidence was generally lower compared with the continuous cultivation. On the aerial part of the ginseng infected by C. desiccates, the end and/or margin of leaves were changed to dark reddish color that appeared for behind the root-rot symptom. In this field, the longitudinal growth of lateral root was more inhibited than in the case of the replanted cultivation by C. destmctans. The inhibition rate of rootlet growth was 37.3% in the continuous cultivation as compared with that of replanted cultivation at June 14. Though lesions of root-rot were formed all over the roots, 61.2% of the lesions was positioned within 6 cm under the rhizome. Key words Panax ginseng, Cylindrocarpon destmtan, root-rot of ginseng, replanting problem of ginseng.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.1
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• pp.49-54
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• 1988

The present experiment was conducted to investigate causes affecting the reduction of red pepper production in the continuous cultivation upland soil from 1985 to 1986 in Imsil Chonbuk Province. The results obstained are summarized as follows: 1. Area ratio of continuous cultivation 2 years was 12.7%, 3 years 6.8% and over 4 years 48.9%. 2. Soil hardness and volume of solid and liguid of red pepper continuous cultivation soil were higher than those of one year cultivation, while pH and content of organic matter of continuous cultivation soil were low. The exceeding optimum level of phosphorus and potassium appeared factors affecting and reduction of red pepper of continuous cultivation soil. 3. Microflora density in continuous cultivation soil was high but bacteria/fungi (B/F) and actinomycetes/fungi (A/F) ratio were low. 4. The density of soil nematodes in continuous cultivation soil were higher than that in one year cultivation soil, however, the steeper and better drainage soil lowered the density of nematodes. 5. Continuous cultivation over 4 years showed 14.3% of plants diseased by phytophthora while 0.7% in one year cultivation soil.

• Korean Journal of Medicinal Crop Science
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• v.28 no.3
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• pp.209-220
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• 2020

Background: This study investigated the effects of soil properties on the soil fungal community in first and continuous cultivation areas of Cnidium officinale Makino. Methods and Results: The soil fungal community was analyzed for relative abundance and principal coordinate analysis (PCoA) was conducted using Illumina MiSeq sequencing. The correlation between the soil chemical properties and the soil fungal community was assessed with distance-based linear models (DISTLM). The soil fungal community showed distinct clusters consisting in the continuous cultivation area of C. officinale Makino. PCoA and DISTLM indicated that soil pH, calcium, and available P₂O₅ significantly affected the soil fungal community in the cultivation area of C. officinale Makino. In addition, considering 5 different pathogenic fungi the relative abundance of Fusarium in the continuous cultivation area was significantly higher compared to that in the first cultivation area of C. officinale Makino. Conclusions: This study is important because it has determinined the effects of soil properties on the soil fungal community in both first and continuous cultivation areas of C. officinale Makino. Moreover, these results will be helpful to investigate the cause of continuous cropping obstacle in C. officinale Makino by examining the changes of soil fungal community.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.270-274
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• 1992

This study was observed to find out the relationship of soil microorgaism physico-chemical properties and yields on the continuous cultivation of peanuts soil in the difference 20 farmes field located in Gochang, Chonbuk area. The results obtained was summarized as follows : 1. Soil hardness and volume of soild and liquid of peanut continuous cultivation soil were higher than those of one year cultuvation. 2. The exceeding optimum level of phosphorus and potassium appeared factors affecting and reduction of peanut continuous cultivation soil. 3. Number of microorgaisms in continuous cultivation soil was high but the ratio of bacteria/fungi (B/F) and actinomycetes/fungi (A/F) ratio were low. 4. The number of soil nematodes in continuous cultivation soil were higher than that of alternative cultivation soil.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.73-78
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• 2018

The main objective of this study was to evaluate the effects of acetate on the cultivation of anabena under mixotrophic condition. Four different types of acetates were used for the anebena cultivation. Among them, ethyl acetate was found to be the most effective and the growth rates linearly increased as the amount of ethyl acetate increased. When 40 mM of ethyl acetate was used, the highest values of specific growth rate of $0.979day^{-1}$ and maximum biomass productivity of $0.293g\;L^{-1}\;d^{-1}$ were obtained. On the contrary, input of acetic acid and butyl acetate inhibited the growth of anabena. For aeration tests, 0.54 vvm was optimum for anabena cultivation. For a semi-continuous cultivation test, ethyl acetate was used after 0.54 vvm test was finished. Then, test continued under 0.54 vvm and 40 mM of ethyl acetate. Lower specific growth rate and maximum biomass productivity were obtained compared to those from batch cultivation tests. However, the greatest maximum concentration of 5.91 g/L was obtained during the semi-continuous cultivation test.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.8
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• pp.523-527
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• 2012

This study was performed to determine optimum conditions of semi-continuous cultivation of chlorella sp. FC-21 cultivated under red light emitting diode (LED). Semi-continuous cultivation was conducted using red LED because red LED was found to be the best light source for chlorella sp. FC-21. During cultivation, phosphate and nitrogen were quickly diminished where cell concentration of chlorella was inversely proportional to the concentrations of phosphate and nitrogen in culture solution. To increase the period of dilution of culture solution, additional amounts of phosphate and nitrogen were inserted in the culture solution to increase the concentrations of phosphate and nitrogen. The cell concentrations of chlorella increased in the modified culture, but cell diameter was diminished as the dilution of culture was periodically conducted. When considered the cell concentration and cell diameter during the cultivation, amount of biomass produced was maintained constant.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.716-721
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• 1999

It has been known that continuous cultivation of hairy root is difficult to maintain for a long period of time compared to the microbial and callus cultures. Chemostat cultivation was successfully carried out in order to economically produce a plant-based colorant, betacyanin, from red beet hairy root for more than 85 days in a 14-1 fermentor. The result from the chemostat cultivation was compared to those of the batch and fed-batch cultivations of red beet hairy roots. It was shown that hairy root reached its steady state within 50 days of the cultivation, and then maintained for about 25-30 days in a wide range of dilution rates. Total betacyanin production from the continuous process was also calculated to be 2.65g at 0.28(l/d) of dilution rate, compared to 0.196g from fed-batch cultivation. It was found that betacyanin production was a partially growth related process, yielding 0.376 mg/g-fresh wt. cell and $1.89{\times}10^{-5}$ mg/g-fresh wt. cell/d, with 0.92 of correlation factor in a partial growth-product model. It was also shown that the cell growth required was relatively large for maintenance amount of energy at a low dilution rate. The growth of hairy root was inhibited by high light intensity in following a photo-inhibition model. The growth parameters were estimated to be 0.3(l/d), $10.56kcal/\textrm{m}^2/h$,{\;}and{\;}35.81kcal/\textrm{m}^2/h$ for the maximum specific growth rate, half saturation light intensity, and inhibition light intensity, respectively.

• Journal of Marine Bioscience and Biotechnology
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• v.10 no.2
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• pp.73-82
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• 2018

Chlorella are source of valuable compounds as lipids, proteins, carbohydrates, bioactive compounds. To continuous obtain the high-value materials of Chlorella protothecoides, we performed continuous cultivation after applying milking techniques to C. protothecoides grown with culture for 7 days in optical panel bioreactor (OPBR) system. Fatty acid and lutein in extracts from pre- and post-milking of C. protothecoides were analyzed using gas chromatography and high performance liquid chromatography, respectively. C. protothecoides were rich in unsaturated fatty acids with a high content of oleic acid(C18:1), which is suitable as a biofuel feedstock. The fatty acid content in pre- and post-milking of C. protothecoides was decreased from 126.424mg/g d.w. to 119.341mg/g d.w, and the lutein content decreased from 0.258mg/g d.w. to 0.178mg/g d.w. The results of this study demonstrate the feasibility of milking C. protothecoides for production of lipids for biofuels production. It was confirmed that microalgae can continuously obtain lutein present in a trace amount through a continuous culture from milking.

• Journal of Pharmacopuncture
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• v.10 no.2 s.23
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• pp.67-71
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• 2007

Objectives : This experimental study was performed to investigate the continuous anti-bacterial potency of Tangpo-san on cultivation of Staphylococcus species(S. aureus, S. epidermidis)that induce eye disease. Methods : Minimal inhibitory concentration(MIC) was measured by dropping to 50 ${\mu}$l diluted Tangpo-san(100%, 10%, 1%, 0.1%) on S. aureus, S. epidermidis that were cultivated from 2 to 6 days. Anti-bacterial potency was measured by the size of inhibition zone with change of volume(20 ${\mu}$l,30 ${\mu}$l,40 ${\mu}$l,50 ${\mu}$l). Results : 1. Anti-bacterial potency of Tanpo-san on S. aureus was not appeared all samples. Anti-bacterial potency with change of volume was increased in propotion to increase volume, and the Anti-bacterial potency of 2 days was equal to 6 days. Anti-bacterial potency of Tangpo-san on S. aureus was appeared continuous. 2. Anti-bacterial potency of Tangpo-san on S. epidermidis was appeared in 100%, 10% on 2 and 6 days, and the Anti-bacterial potency of 6 days was decreased. In 2 days, Anti-bacterial potency was appeared 40 and 50u1, in 6 days, Anti-bacterial potency was appeared all samples. Anti-bacterial potency with change of volume was increased in propotion to increase volume and increased on 6 days, but bacteria was increased. Anti-bacterial potency of Tangpo-san on S. epidermidis wasn't appeared continuous. Conclusions : Anti-bacterial potency of Tangpo-san on cultivation of S. aureus showed continuous, but on cultivation of S. epidermidis was not showed continuous.