• Journal of Ecology and Environment
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• v.42 no.4
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• pp.155-162
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• 2018

Background: In ecosystem carbon cycle studies, distinguishing between $CO_2$ emitted by roots and by microbes remains very difficult because it is mixed before being released into the atmosphere. Currently, no method for quantifying root and microbial respiration is effective. Therefore, this study investigated the relationship between soil respiration and underground root biomass at varying distances from the tree and tested possibilities for measuring root and microbial respiration. Methods: Soil respiration was measured by the closed chamber method, in which acrylic collars were placed at regular intervals from the tree base. Measurements were made irregularly during one season, including high temperatures in summer and low temperatures in autumn; the soil's temperature and moisture content were also collected. After measurements, roots of each plot were collected, and their dry matter biomass measured to analyze relationships between root biomass and soil respiration. Results: Apart from root biomass, which affects soil's temperature and moisture, no other factors affecting soil respiration showed significant differences between measuring points. At each point, soil respiration showed clear seasonal variations and high exponential correlation with increasing soil temperatures. The root biomass decreased exponentially with increasing distance from the tree. The rate of soil respiration was also highly correlated exponentially with root biomass. Based on these results, the average rate of root respiration in the soil was estimated to be 34.4% (26.6~43.1%). Conclusions: In this study, attempts were made to differentiate the root respiration rate by analyzing the distribution of root biomass and resulting changes in soil respiration. As distance from the tree increased, root biomass and soil respiration values were shown to strongly decrease exponentially. Root biomass increased logarithmically with increases in soil respiration. In addition, soil respiration and underground root biomass were logarithmically related; the calculated root-breathing rate was around 44%. This study method is applicable for determining root and microbial respiration in forest ecosystem carbon cycle research. However, more data should be collected on the distribution of root biomass and the correlated soil respiration.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.328-328
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• 2017

Drought is a major limiting factor that reduces rice production and occurs often especially under recent climate change. Plants have the ability to alter their developmental morphology in response to changing environment, which is known as phenotypic plasticity. In our previous studies, we found that one chromosome segment substitution line (CSSL50 derived from Nipponbare and Kasalath crosses) showed no differences in shoot and root growth as compared with the recurrent genotype, Nipponbare under non-stress condition but showed greater growth responses compared with Nipponbare under mild drought stress condition. We hypothesized that reducing root respiration as metabolic cost, which may be largely a consequence of aerenchyma formation would be one of the key mechanisms for root plasticity expression. This study aimed to evaluate the root respiration and aerenchyma formation under various soil moisture conditions among genotypes with different root plasticity. CSSL50 together with Nipponbare and Kasalath were grown under waterlogged conditions (Control) and mild drought stress conditions (20% of soil moisture content) in a plastic pot ($11cm{\times}14cm$, ${\varphi}{\times}H$) and PVC tube ($3cm{\times}30cm$, ${\varphi}{\times}H$). Root respiration rate was measured with infrared gas analyzer (IRGA, GMP343, Vaisala, Finland) with a closed static chamber system. There was no significant difference between genotypes in control for shoot and root growth as well as root respiration rate. In contrast, all the genotypes increased their root respiration rates in response to mild drought stress. However, CSSL50 showed lower root respiration rate than Nipponbare, which was associated by higher root aerenchyma formation that was estimated based on internal gas space (porosity) under mild drought stress conditions. Furthermore, there were significant negative correlations between root length and root respiration rate. These results imply that reducing the metabolic cost (= root respiration rate) is a key mechanism for root plasticity expression, which CSSL50 showed under mild drought.

• The Korean Journal of Ecology
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• v.24 no.2
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• pp.87-91
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• 2001

The response of respiration rates of root, Ao layer and mineral soil to varying environmental factors was studied in Popuius maximowiczii stand (25-year-old) during the growing season of 1997. Soil temperature showed a pronounced seasonal course, in contrast to soil moisture. The mineral soil respiration was high in August, and root and Ao layer respiration, were high in July. An exponential equation best described the relationships between soil temperature and mineral soil respiration, and total soil respiration (r＝0.95 and 0.92, p＜0.001), respectively. In P. maximowiczii stand, soil respiration rates were reduced by about 19% after removal of the Ao layer, and by about 30% after removal of living root. Therefore, mineral soil respiration seemed to contribute gretly to the total soil respiration (50%).

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.28-34
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• 2005

We review three methods of separating soil respiration into root and soil microbial contribution: (1) component integration, (2) root exclusion, and (3) isotopic method. Among these methods, component integration and root exclusion are most commonly used. Root respiration contribution to soil respiration estimated by the root exclusion method is higher than those by other two methods. Trenching has little environmental disturbances in soil or on surface of site compared to other methods in root exclusion such as root removal and gap formation. Isotopic method has an advantage over other methods because of minimal soil and root disturbances, but this method is costly and requires techniques for the complex analysis. Trenching seems to be an appropriate in situ method for calculating component contributions to soil respiration with minimum disturbances in site. However, the method overestimates the contribution of microbial respiration because of root decay, and realistic results could be obtained by estimating root decay or avoiding large roots in trenched plots.

• Journal of Ginseng Research
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• v.10 no.2
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• pp.180-186
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• 1986

Photosynthesis and respiration of leaf and root of field grown Panax ginseng were investigated according to aerial part sensecence. No apparent photosynthesis activity was detected in senescenced leaf(less than 0.7mg total chlorophyll/g FW) and leaf dark respiration was consistent relation with senescence. Leaf respiratory Q$_{10}$ consistently increased with senscence. Root respiration and Q$_{10}$ tended to decrease with aerial part senescence only in the range of optimum temperature of leaf growth. Apparent photosynthesis or respiration of leaf was negatively or positively correlated, respectively with the increase of air temperature. Root respiration with temperature was well accordance with Arrhenius plot which was not consistent with aerial part senescence. Accelerated senescence may be recommendable for better root yield unless any reserve in stem or leaves contributes to root through translocation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.4
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• pp.1-11
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• 1979

Increased nitrogen fertilization increased root respiration and top dry weight of rice plant, and increased phosphorus fertilization increased root respiration only with the same amount of nitrogen applied. The effect of phosphorus on root respiration under low growth temperature was not significant and the large application of phosphorus alone decreased root respiration greatly. Root respiration per unit root weight correlated highly with top dry weight and nutrient uptake.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.2
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• pp.154-157
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• 1985

This study was conducted to know the respiration rate in different organ of 4 years old ginseng plant on June 14 and in different root conditions of 6 years old on October 1. Respiration rate of each organ was the increasing order of young berry, leaf, peduncle, stem and root at all temperature(15$^{\circ}C$ to 30$^{\circ}C$). Temperature coefficients of respiration rate from 15$^{\circ}C$ to 30$^{\circ}C$ of each organ were 2.39 in young berry, 1.75 in leaf, 1.57 in root, 1.17 in stem and 1.16 in peduncle. There was no difference between respiration rate of large size root (117${\pm}$8.8g) and that of small size (54${\pm}$4.0g) in 6 years old ginseng. Respiration rate was decreased with the decrease in the water content in root, especially in small size root. And respiration rate of red skin root was higher than that of healthy root.

• Journal of Ginseng Research
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• v.22 no.3
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• pp.161-167
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• 1998

American ginseng plants (Panax quinquefolium L.) of various ages were harvested every two weeks during each of three growing seasons and dry matter yield of components and root respiration determined. Shoot dry weight was about 0.5 g, 2.5 g and 4 g for 2, 3 and 4-year-old plants, respectively and fruit dry weight was as much as 50% of this in 3- and 4-year-.old plants. Root dry weight decrease by 30~50% as shoots emerged and at the end of the season was about 2 g, 3.5 g and 5 g in 2, 3, 4 and 5-year-old plants, respectively. Shoot and root dry weight were linearly related with an approximate 1:2 ratio. Root respiration rate at 2$0^{\circ}C$ in the dark was about 5 $\mu\textrm{g}$ CO2 g-1 DW(dry weight) min-1 in the early season, then doubled within 50 days as shoots emerged, and thereafter declined over the season to 2~5 $\mu\textrm{g}$ CO2 g-1 DW min-1. The Q10 for dark respiration over the interval from 10 to 2$0^{\circ}C$ was 1.58. Root respiration rate and shoot growth rate was positively linearly related in all ages of plants. Key words: Dry weight, partitioning.

• Journal of Ecology and Environment
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• v.34 no.2
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• pp.193-202
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• 2011

We studied temperature sensitivity characteristics of soil respiration during periods of rising and falling temperatures within a common temperature range. We measured soil respiration continuously through two periods (a period of falling temperature, from August 7, 2003 to October 13, 2003; and a period of rising temperature from May 2, 2004 to July 2, 2004) using an open-top chamber technique. A clear exponential relationship was observed between soil temperature and soil respiration rate during both periods. However, the effects of soil water content were not significant, because the humid monsoon climate prevented soil drought, which would otherwise have limited soil respiration. We analyzed temperature sensitivity using the $Q_{10}$ value and $R_{ref}$ (reference respiration at the average temperature for the observation period) and found that these values tended to be higher during the period of rising temperature than during the period of falling temperature. In the absence of an effect on soil water content, several other factors could explain this phenomenon. Here, we discuss the factors that control temperature sensitivity of soil respiration during periods of rising and falling temperature, such as root respiration, root growth, root exudates, and litter supply. We also discuss how the contribution of these factors may vary due to different growth states or due to the effects of the previous season, despite a similar temperature range.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.362-369
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• 1990

In order to determine the mechanism of saline stress, forage plants were irrigated with sea water. Saline stress was investigated on photosynthesis, root respiration, evapotranspiration and visual symptoms. All crops showed increased relative evapotranspiration and relative photosynthesis under low temperature (11-16$^{\circ}C$) rather than high temperature (22-24$^{\circ}C$). The correlation coefficients calculated for each crop between relative evapotranspiration and root respiration were 0.996$\^$**/ for orchard grass, 0.828$\^$*/ for alfalfa and 0.963$\^$**/ for white clover. No significant correlation coefficient between relative evapotranspiration and root repiration was found for the tall fescue. The effects of OED spray on the evapotranspiration and root respiration of crops in the sea watered pots were low compared with those in the fresh watered pots. When OED was sprayed and zeolite was used, the evapotranspiration and root respiration were low compared with check pots and sand pots. The root damage due to sea water treatment was characterized by brown colored root cortex in orchard grass and tall fescue, and water penetration of root cortex in alfalfa and white clover.