• The Korean Journal of Ecology
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• v.22 no.3
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• pp.139-144
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• 1999

In order to clarify ecological survival strategy of Rumex crispus community dominating under contaminated area of lower region of Kumho riverside including Chimsangyo (CS), Paldalgyo (PD), Talseochon (TS) and Kumhogyo (KH), we analyzed the content of heavy metals and inorganic matter and vegetative growth. R. crispus showed rapid formation of community by high growth rate, high T/R ratio and showed maximum T/R ratio at the contaminated area Talseochon. Nitrogen and phosphorus contents in R. crispus showed high value in shoot than that of root. T/R ratio of nitrogen and phosphorus showed 3.1∼3.6 and 1.5∼4.5 for the early growth stage, and 6.7∼17.3 and 3.9∼8.3 for the late one, respectively. The absorbed heavy metals by riot were translocated to shoot, the heavy metal content in shoot higher than those in root of Cu, Zn, Fe, and Pb for 3.6, 1.7, 1.5 and 4.8 times, respectively. Distribution ratio of the heavy metals in each organ showed 61∼85% and 15∼39% for shoot and root, respectively. R. crispus accumulated heavy metals in the order of Fe>Zn>Cu>Pb in shoot, and showed maximum values of Cu, Zn, Fe and Pb for 89.7, 376.6, 2946.1 and 13.2 ㎍/g dw, respectively at Talseochon in April. A physiological and morphological characteristics of R. crispus showed thickened leaf, increased water content above 80% and rapid growth of shoot. R. crispus showed ecological adaptation to the contaminated area by transportation of heavy metals and inorganic matter to shoot, and by accumulation of Ca ion in root.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.237-246
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• 1995

Larvae of the freshwater shrimp, Macrobrachium nipponense were reared in the laboratory at constant condition $(25^{\circ}C,\;7\%o)$, and their feeding rate, oxygen consumption rate, and growth rate were measured in regular intervals of time during larval development. Regression equations describing rates of feeding, growth and respiration as functions of time during individual larval molt cycles were inserted in a simulation model in order to analyse time-dependent patterns of variation as well as in bioenergetic efficiencies. Absolute values for feeding, growth, respiration and assimilation showed clear changes during the molt cycle, The absolute and specific values of respiration (R: R/C) showed small variation during the individual molt cycles. Significance of respiration in relation to growth (G) increased within the carbon budget, respiration rate (R/C) outbalanced growth rate (G/C) in late premolt. When the portion of metabolizable carbon is respired (R/G), metabolic coefficient was < 1 (i.e. R$(K_2)$ decreased concurrently, In cumulative carbon budget, total feeding was $491.54\;{\mu}g$ C/ind., assimilation was $85.3\%$, respiration was $47.7\%$, and growth was $37.6\%$ from hatching to postlarval stage.

• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.1
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• pp.25-30
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• 1987

There are differences in opinion as to whether nitrogen fertilizer should be used when establishing alfalfa (Medicago sativa L.). Various reports show that under a hot environment, rhizobia (Rhizobium meliloti) are not as effective in fixing atmospheric nitrogen as they are under moderate temperatures. It is also believed that the addition of nitrogen fertilizer inhibits nodulation of alfalfa seedlings. A replicated experiment was conducted under controlled environmental conditions at the University of Nevada-Reno, Reno, Nevada, USA, to determine the effects of nitrogen application on seedling growth and nodulation of alfalfa grown in a hot environment. Sterile sand was used as the growing media to which a complete nutrient solution minus nitrogen was applied volumetrically to each pot daily. In addition, half of the pots received NH4-$NO_3$, at the rate of 11.2 kg per ha at seeding and at two and four weeks after planting giving a total nitrogen application rate of 33.6 kg per ha during the seven-week experimental period. Rhizobia inoculant (R-12) consisted of a mixture of strains 171-15a, 1682c and 80 PI 265 of (Rhizobium meliloti). Inoculant was applied to the seeds prior to planting and to the sand media at two and four weeks after seeding. Twenty seeds were planted in pots 14.0 cm in diameter and 11.5 cm deep. Plants were thinned to ten plants per pot after emergence and were grown in a controlled environment chamber with a 16-hour light period. Soil temperature at 6 cm depth ranged from 17.4^{\circ}C.$ to 31.1^{\circ}C.$ and had a daily mean of 26.5^{\circ}C.$. Plants were harvested at weekly intervals for seven weeks. Root, shoot and total length, dry weight, volume and number of nodules per plant were determined. Root, shoot, and total length were greater in seedlings grown in soil where nigrogen was applied than that grown in soil to which no nitrogen was applied. The average size of the seedlings as determined by volume and weight was more than two times greater where plants were fertilized with nitrogen. Nodule number per seedling was also greater when nitrogen was applied compared to those which received no nitrogen. The differences were greater as the plants became older. The rhizobia did not fix enough nitrogen for adequate growth of seedlings. This is probably due to high temperature growing conditions that caused the rhizobia to become relatively ineffective as compared to cooler growing conditions. Data suggests it would be desirable to apply nitrogen at seeding when alfalfa is established under hot conditions that occur in mid- or late summer.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.1
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• pp.75-78
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• 1971

A theory and method on the economic allocation of a limitted amount of fertilizer to different crops which show different responses to the application of fertilizers was discussed. If the amount of fertilizer is not enough for all the crops which a farmer plans to grow, the fertilizer should be shared among the crops so as to maximize his profit from all his crops. According to the theory and method discussed here 9.14, 7.11 and 8.75kg per ha./10 of nitrogen should be allocated to rice, barley and wheat instead of 10, 7.5 and 7.5kg per ha./10 which were the amount allocated by the Government of Korea in 1968. The theory could also be with advantage applied to the planning of national fertilizer allocation.

• The Korean Journal of Ecology
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• v.24 no.3
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• pp.157-168
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• 2001

Herbicides have been used to control weeds for decades. If detoxification upon exposure to herbicides requires considerable amounts of energy, it could affect the pattern of resource allocation to growth and reproduction of crops. We examined the effects of three levels of a herbicide (Control, Low, and High) on germination, growth and reproductive characters of Glycine max treated twice, i.e., before and after seed germination. Since flowering time of G. max was separated into two groups, flowering time was also considered as a variable in this study. The rate of seed germination tended to be higher at the low level of herbicide compared to other levels. Chlorosis and shape variation of leaves were apparent after the second herbicide treatment, but completely disappeared after six weeks of treatment. The herbicide effects on growth characters were somewhat different between early and late flowering plants, but plants treated with both low and high levels of herbicide reduced their growth compared to those in the control group regardless of flowering time. Plants at the high level of herbicide exhibited the highest growth rate later in the season, suggesting that plants compensated to some extent for reduced growth. However, growth reduction among plants at the high level of herbicide was persistent until the end of growing season. Among plants flowered late in the season, plants in the control level bore a higher number of nodules per plant than those in other levels; such a pattern did not exist among plants flowered early in the season. Plants treated with low and high levels of herbicide produced a lower number of flowers than those in the control. Thus, the herbicide examined affected not only the growth and reproductive characters of non-target crops but also the development and growth of root nodules.

• Journal of Korean Society of Forest Science
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• v.87 no.2
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• pp.276-285
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• 1998

The aboveground biomass and nutrient content (N, P, K, Ca and Mg) of Pinus koraiensis S. et Z., aged 9, 22, 34, 46, 66 years, were measured in the Experiment Forest of Kangwon National University of Kangwondo province. The site index of the stands ranged from 13.5 to 14.2. Allometric equations (logY=alogX+b, where Y, X is ovendry mass and DBH, respectively) relating dry weights of stem, branches and needles to diameter at breast height (DBH) were developed to estimate aboveground tree biomass. Total above ground tree biomass increased with stand age from $21.8t\;ha^{-1}$ in the 9-year-old stand to $130t\;ha^{-1}$ in the 66-Year-old stand. Aboveground biomass was allocated as follows : stem> branch > foliage, except for the 9-year-old stand which had a greater proportion of foliage biomass than branch biomass. As stand age increased, an increasing proportion of annual biomass increment was allocated to stems. The aboveground biomass of shrubs and herbs ranged from 0.4 to $3.9t\;ha^{-1}$ and from 0.05 to $0.6t\;ha^{-1}$, respectively. No relationship was found between aboveground understory biomass and stand age. The mass of woody debris and forest floor varied between 0.59 to $1.54t\;ha^{-1}$ and 6.0 to $21.63t\;ha^{-1}$, respectively. Nutrient accumulation in aboveground tree biomass increased with stand age and was in the order of N > Ca > K > P > Mg. Average rates of nutrients accumulation in biomass were greatest in the early stages of stand development, and less marked as stand aged. The nutrient concentrations in different tree components decreased in the order of needle > branch > stem. There were no detectable trends in nutrient content of the forest floor and mineral soils with stand age. Understory vegetation contributed little to the nutrient pool of these Korean pine ecosystems. Mineral soil contained the Breast proportion of nutrient capital of the various ecosystem compartments.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.35-41
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• 2008

Nutrient Enrichment Bioassays (NEBs) were conducted in the laboratory during June $22{\sim}28$, 2006 in order to determine primary limiting factor on the phytoplankton growth. For the NEBs, the water was sampled using a 10L polyethylene-lined container and dispensed into 2.5L container in the laboratory. The algal growths response in the control (C) and three treatments of phosphorus (P), 2-fold phosphorus (2P), and nitrate nitrogen $(NO_3-N)$ were monitored during 7 days. In the cubitainers which were spiked as P (T1) and 2P (T2) Chl-${\alpha}$ concentrations were decreased during the test period and the final concentrations was low than initial values. However, Chl-${\alpha}$ in the cubitainers which were spiked as $NO_3$(T3) and $P+NO_3$(T4) showed significant increases compared to the initial values, indicating that in the short-term experiments, nitrogen seemed to be a primary limiting nutrient during the periods of NEBs experiment. Long-term ambient nutrient data of TP and TN, and TN:TP mass ratios, however, showed a potential phosphorus limitation on phytoplankton growth and previous other researchers showed a variations of limiting nutrients by nitrogen or phosphorus depending on the seasons sampled and locations. In this study nitrogen as primary limiting nutrient in the NEBs seem to be an seasonal effect rather than the consistent nitrogen limitation.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.2
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• pp.114-123
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• 2009

To investigate the possible use of plants for landscaping in reclaimed soil, a planting pilot system experiment was performed over the course of four years in reclaimed dredging area with four species: Alnus firma, Alnus hirsuta, Pinus thunbergii, and Pyrachantha angustifolia for 4 years. The physicochemical characteristics of the tested soil showed that it was sandy through coming from a reclaimed dredging area. The average pH of the tested soil was 7.16(slight alkali), and electric conductivity(EC) was relatively low, $294{\mu}S/cm$, even though it came from a saltwater area. To test the effect of planting density vs. phytomass by plant specie from a planting basin, the experiment was designed using four plant species with high and low planting densities over 4 years. The planting conditions of the growth of landscape tree species exhibited growth height as follows: A. hirsuta, A. firma, P. thunbergii, and P. angustifolia, whill the DBH followed the order of A. hirsuta, A. firma, and P. thunbergii. The total phytomass of each plant was higher at low density planting areas than high density planting area in terms of total phytomass production and growth distribution in the reclaimed dredging area. Total phytomass per unit area increased as follows: A. hirsuta, A. firma, P. thunbergii, and P. angustifolia. The total phytomass per each tested plant was 2 times higher in low density planting areas than high density planting areas. Total phytomass per unit area, however, was similar or slighty higher in high density planting areas compared to low density areas. Among the tested plants, A. hirsuta showed the highest phytomass, implying that A. hirsuta adapted very well to the reclaimed area and has the capability of a fast growth, nitrogen fixation tree, and utilizing insoluble nutrients through inoculated root nodule bacteria. The yield of phytomass per individual in low density Alnus species was greater than that of the high density. However, those per unit areas had no difference in the density-dependent planting. The ratio of belowground to aboveground was $0.21{\sim}0.26$. Thus, it could be concluded that the Alnus species are potential candidates for ornamental tree species in reclaimed dredging areas. This study offers baseline data for the use of ornamental tree species in reclaimed dredging areas. Additional research is required for different ornamental species in order to increase phytomass of a planting conditions based on reclaimed dredging areas.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.279-288
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• 2014

To understand changes in composition and distribution of nutrients during early shoot growth of persimmon, organic compounds and inorganic elements of terminal shoots were analyzed for about 40 days from the time of foliation. Sample shoots were collected from mature 'Fuyu' trees for this three-year experiment and they were divided to stem, leaves, and the fruits including flower buds at the earliest stage. During shoot growth, concentration of soluble sugars increased in both leaves and fruits, but that of starch increased only in leaves. Those of amino acids tended to decrease in all the parts but there was no consistent change in proteins. As shoots grew, contents of all the organic compounds in a shoot increased, and they were especially higher in May leaves accounting for more than 60% of the shoot total for each nutrient. Along with shoot growth, concentrations of N and P gradually decreased in all three parts, while K decreased only in stem. However, those of Ca and Mg did not show notable changes in all the parts with wide variations depending on the year. Due to the quantitative increase in growth, contents of inorganic elements in a shoot increased in all the parts and the leaves accounted for 54-82% of the shoot total. At the cessation time of extension growth, a shoot contained 526-768 mg of soluble sugars, 245-844 mg of starch, 26-31 mg of amino acids, and 66-103 mg of proteins for three years. On the other hand, a shoot contained 203-388 mg of K, the greatest among the inorganic elements, followed by 132-159 mg of N. Changes of the nutrients in a shoot were much greater during the earlier stage of growth after foliation than during the later stage toward growth cessation, suggesting the importance of mobilizing reserve nutrients for the early growth of the shoots. The results of this study also suggested that the rate of nutrient changes, especially during the earlier stage of shoot growth, could be affected by environmental and cultural conditions.

• Korean Journal of Environmental Agriculture
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• v.32 no.3
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• pp.214-223
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• 2013

BACKGROUND: This study focused on the development of an analytical method about dichlorprop (DCPP; 2-(2,4-dichlorophenoxy)propionic acid) which is a plant growth regulator, a synthetic auxin for agricultural commodities. DCPP prevents falling of fruits during their growth periods. However, the overdose of DCPP caused the unwanted maturing time and reduce the safe storage period. If we take fruits with exceeding maximum residue limits, it could be harmful. Therefore, this study presented the analytical method of DCPP in agricultural commodities for the nation-wide pesticide residues monitoring program of the Ministry of Food and Drug Safety. METHODS AND RESULTS: We adopted the analytical method for DCPP in agricultural commodities by gas chromatograph in cooperated with Electron Capture Detector(ECD). Sample extraction and purification by ion-associated partition method were applied, then quantitation was done by GC/ECD with DB-17, a moderate polarity column under the temperature-rising condition with nitrogen as a carrier gas and split-less mode. Standard calibration curve presented linearity with the correlation coefficient ($r^2$) > 0.9998, analysed from 0.1 to 2.0 mg/L concentration. Limit of quantitation in agricultural commodities represents 0.05 mg/kg, and average recoveries ranged from 78.8 to 102.2%. The repeatability of measurements expressed as coefficient of variation (CV %) was less than 9.5% in 0.05, 0.10, and 0.50 mg/kg. CONCLUSION(S): Our newly improved analytical method for DCPP residues in agricultural commodities was applicable to the nation-wide pesticide residues monitoring program with the acceptable level of sensitivity, repeatability and reproducibility.