• Journal of Ecology and Environment
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• v.42 no.1
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• pp.43-49
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• 2018

Iris laevigata is geographically restricted and legally protected in Korea. In this study, a mesocosm study was conducted to examine the effects of environmental conditions such as water levels and soil nutrient conditions on the growth and survival of I. laevigata seedlings. Complete submergence lowered the total number of leaves, biomass, and survival rates. A rise in soil nutrients increased overall seedling growth and increased tiller numbers via the promotion of asexual reproduction. Also, we found that the lowest measured values of seedlings are associated with the most stressful condition due to the interaction of low soil nutrients and high water levels. I. laevigata seedlings, however, are distributed in low-nutrient habitats such as floating mat, even though they do not grow well under these conditions. This study suggests that I. laevigata does not prefer low-nutrient condition but choose another benefit such as low competition. Also, the water level must be lower than the seedling height for effective growth and management of I. laevigata.

• ALGAE
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• v.32 no.2
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• pp.139-153
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• 2017

The ability of a red tide species to take up nutrients is a critical factor affecting its red tide dynamics and species competition. Nutrient uptake by red tide species has been conventionally measured by incubating nutrient-depleted cells for a short period at 1 or 2 light intensities. This method may be applicable to certain conditions under which cells remain in oligotrophic water for a long time and high nutrients are suddenly introduced. Thus, a new method should be developed that can be applicable to the conditions under which cells are maintained in eutrophicated waters in healthy conditions and experience light and dark cycles and different light intensities during vertical migration. In this study, a new repletion method reflecting these conditions was developed. The nitrate uptake rates of the red tide dinoflagellate Prorocentrum micans originally maintained in nitrate repletion and depletion conditions as a function of nitrate concentration were measured. With increasing light intensity from 10 to $100{\mu}E\;m^{-2}s^{-1}$, the maximum nitrate uptake rate ($V_{max}$) of P. micans increased from 3.6 to $10.8 pM\;cell^{-1}d^{-1}$ and the half saturation constant ($K_{s-NO3}$) increased from 4.1 to $6.9{\mu}M$. At $20{\mu}E\;m^{-2}s^{-1}$, the $V_{max}$ and $K_{s-NO3}$ of P. micans originally maintained in a nitrate repletion condition were similar to those maintained in a nitrate depletion condition. Thus, differences in cells under nutrient repletion and depletion conditions may not affect $K_{s-NO3}$ and $V_{max}$. Moreover, different light intensities may cause differences in the nitrate uptake of migratory phototrophic dinoflagellates.

• Ocean and Polar Research
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• v.32 no.2
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• pp.97-111
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• 2010

Phytoplankton production is affected by various physico-chemical factors of environment. However, one of the most critical factors generally accepted as controlling primary production of phytoplankton is nutrients. It has recently been found that the succession of phytoplankton groups and species are closely related to the chemical properties of ambient water including nutrient limitation and their ratios. In Jangmok Bay, silicate and nitrate are primarily supplied by rainfall, while phosphate and ammonia are supplied by wind stress. Typhoons are associated with rainfall and strong wind stress, and when typhoons pass through the South Sea, such events may induce phytoplankton blooms. When nutrients were supplied by heavy rainfalls during the rainy season and by summer typhoons in Jangmok Bay, the dominant taxa among the phytoplankton groups were found to change successively with time. The dominant taxon was changed from diatoms to flagellates immediately after the episodic seasonal events, but returned to diatoms within 3~10 days. Pseudo-nitzschia spp. were dominant mainly in the presence of low phosphate levels during the first of the survey which included the rainy season, while Skeletonema costatum was dominant when phosphate concentrations were high due to the strong wind stress during the latter half of the survey as a result of the typhoon. The competition between S. costatum and Chaetoceros spp. appeared to be regulated by the silicate concentration. S. costatum preferred high silicate and phosphate concentrations; however, Chaetoceros spp. were able to endure low silicate concentrations. These results implied that, in coastal ecosystems, the input patterns of each nutrient supplied by rainfall and/or wind stress appeared to contribute to the summer succession of phytoplankton groups and species.

• Korean Journal of Community Nutrition
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• v.22 no.6
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• pp.495-506
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• 2017

Objectives: Weight control practices are common in combat sport athletes. This study was performed to examine nutrient intakes of male college combat sport athletes (taekwondo, boxing, judo) by weight control (WC) status. Methods: Subjects were male combat sport athletes (n=90) from colleges in Gyeonggi Province. Survey was conducted during 2016. Questionnaire included general characteristics, weight control, and dietary intakes during the period of training, weight control, weigh-in ~ before competition and between competitions. Subjects were grouped into high- and normal WC groups. T-test, ${\chi}^2-test$, Fisher's exact test and ANCOVA were used to analyze the data. Results: During training, energy intake was 75.4% of EER and C:P:F ratio was 57.5:13.9:28.7. Iron and zinc intakes were different by WC groups (p<0.05). During weight control, energy intake was 44.7% of EER in normal WC and 30.5% in high WC group (p<0.05). C:P:F ratio was 69:11.1:19.5, and ratio from protein and fat was lower in the high WC group (p<0.05). Most nutrient intakes during weight control were less than 50% of 2015 KDRIs (RNI or AI), and intakes including thiamin (p<0.01), vitamin A, riboflavin, niacin, folate, calcium, potassium and zinc (p<0.05) were significantly lower in the high WC. Energy intake after weighing before the competition was 1,315 kcal, and energy (kcal/kg BW, p<0.05) and carbohydrate intakes (g/kg BW, p<0.01) were significantly higher in the high WC group. Energy intake between competitions was 691.1 kcal, with no difference by the WC group. Conclusions: Nutrients intakes of combat sport athletes were inadequate. Dietary intakes during weight control were much below than the KDRIs, especially in the high WC group. It is needed to develop nutrition education programs for combat sport athletes to avoid severe energy restrictions and to apply specific dietary guides to each period of training and weight control.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.104.1-104
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• 2003

To screen for potential biocontrol agents against postharvest disease of garlics caused by Penicillium hirsutum, a total of 933 isolates (432 fungi and 501 bacteria) were isolated from the rhizoshere or rhizoplane of garlics. Among them, Pantoea agglomerans isolate 59-4 (Pa 59-4) was selected for a potential biocontrol agent by in vivo wounded garlic bulb assay, When the spore suspension (10$\^$5/ spores/$m\ell$) of Penicillium hirsutum was co-inoculated with spore or cell suspension of each fungal or bacterial isolate on wounded garlics, the isolate highly suppressed disease development. Soaking garlic bulbs in the suspension of Pa 59-4 significantly reduced garlic decay from p. hirsutum. However, Pa 59-4 did not inhibit the mycelial growth of P. hirsutum in dual-culture with P. hirsutum on Tryptic soy agar. In order to elucidate mode of action of Pa 59-4 nutrient competition between Pa 59-4 and P. hirsutum was investigated using tissue culture plates with cylinder inserts containing defusing membrane reported by Janisiewicz et al. The results showed that Pa 59-4 effectively suppressed spore germination and mycelial growth of blue mold in the low concentration (0.5％) of garlic juice, but did not suppress those of blue mold in the higher concentration (5％) of garlic juice. This result suggests that the mechanism in biocontrol of garlic blue mold by Pa 59-4 may involve in nutrient competition with P. hirsutum on garlic bulbs.

• Journal of Microbiology
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• v.43 no.3
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• pp.308-312
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• 2005

The global RNA transcription profiles of Bacillus lentimorbus WJ5 under an in vitro co-culture with Colletotrichum gloeosporioides were analyzed in order to study the antagonistic bacteria-fungi interactions. Using a filter membrane system, B. lentimorhus WJ5 was exposed to the spores of C. gloeosporioides at the late exponential stage. The transcription profiles of the B. lentimorhus WJ5, both with and without a challenge from C. gloeosporioides, were analyzed using custom DNA chips containing 2,000 genome fragments. A total of 337 genes were expressed, with 87 and 47 up- and down-regulated, respectively. Of these, 12 genes, which were involved in central carbon metabolisms, and 7 from minor catabolism were relatively highly up-regulated (> 10 fold) and down-regulated (< 0.2 fold), respectively. Nine genes, which were thought to be related to the antifungal activity, were also up-regulated, but their levels were not so high (2.0 - 9.7 folds). From the results, during the early stage of the co-culture of B. lentimorbus WJ5 and C. gloeosporioides, nutrient competition seemed to occur; therefore, the genes from central carbon metabolisms could be up-regulated, while those from minor catabolism could be down-regulated.

• Journal of Korean Society of Forest Science
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• v.86 no.1
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• pp.1-8
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• 1997

Second year results are presented from a trial designed to quantify the reduction in radiata pine(Pinus radiata D. Don) seedling growth caused by competition from a range of important weed species on a moist North Island site in New Zealand. Radiates pine seedlings(1/0) were grown on the weed free control and with either herbaceous broadleaves, grass, broom, pampas, buddleia, or gorse. Resource(nutrient and water) levels were varied by factorial +/- irrigation and fertilizer treatments. Radiata pine seedling volume growth 21 months after planting was greatest when it was grown on the weed free control or in association with gorse, and was least when grown with either buddleia or pampas. There was no evidence that the effects of the weeds on seedling growth were mediated by either competition for water or nutrients. Tall, fast-growing species that overtopped the seedlings(broom, buddleia, pampas) had the greatest effect on seedling growth and the magnitude of the effect was correlated with degree of overtopping. This implies that shading or competition for light is probably an important factor.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.674-682
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• 2009

Recently, the occurrence of harmful algae blooms from the Chattonella group has been increasing and expanding in the southern and western seas of Korea. We investigated the relationship between growth kinetics and nutrients in the harmful algae Chattonella marina and Chattonella ovata of the South Sea, Korea. As a result; high concentrations of ammonium ($30\;{\mu}M$ and above) was not effective to the growth of C. ovata, while C. marina displayed good growth at concentration of $100\;{\mu}M$. The half-saturation constant ($K_s$) of C. marina for ammonium ($2.51\;{\mu}M$), nitrate ($5.36\;{\mu}M$) and phosphate ($0.75\;{\mu}M$) was higher than C. ovata (1.85, 4.01, and $0.61\;{\mu}M$, respectively). This indicates that C. ovata can achieve higher cell densities than C. marina under lower nutrient conditions. These $K_s$ values were comparatively higher than those of diatoms and other flagellates previously reported. Therefore, our results indicate that the growth of C. marina and C. ovata is less adapted to lower nutrient environments than other competition species, such as Skeletonema costatum and Cochlodinium polykrikoides.

• Journal of Environmental Science International
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• v.14 no.9
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• pp.873-879
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• 2005

This study was investigate to evaluate the phosphate uptake rate of green algae in relation to diurnal rhythm and algae control method. The phosphate uptake rates of Chlorella vulgaris and Ankistrodesmus convolutus increased in light period and decreased in dark period. On the contrary, those of Chlamydomonas sp. showed a peak in the late dark period. The differences among species in phosphate uptake in relation to diurnal rhythm were due to the severe competition among species and seemed to alleviate the competition for nutrient supplies. The compound of CellCaSi, Ca and Fe showed the effective removal of the phosphorus. The extracts from rice and barley straw exhibited a significant effect on the growth inhibition of Microcystis aeruginosa.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.4
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• pp.232-242
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• 2014

We investigated the interspecific competition between the harmful dinoflagellate Cochlodinium polykrikoides and diatom Skeletonema sp. based on the utilization and uptake of dissolved organic nutrients. C. polykrikoides and S. costatum were able to grow using dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) as well as dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP). This result indicates that the utilization of dissolved organic nutrients may play a role in surviving strategy in the DIN or DIP-limited environments. The half-saturation constants (Ks) of urea and glycerophosphate (glycero-P) calculated from uptake kinetics experiment of C. polykrikoides was lower than those of Skeletonema sp. This result indicates that Skeletonema sp. have higher affinity for dissolved organic nutrients, such as urea and glycero-P, than C. polykrikoides. Although Skeletonema sp. have higher affinity of dissolved organic nutrients, C. polykrikoides could effectively uptake for urea and glycero-P at sub-saturating nutrient concentrations (${\alpha}$ (${\rho}_{max}/Ks$) of C. polykrikoides was higher than Skeletonema sp.. Therefore, C. polykrikoides by utilization and effectively uptake of dissolved organic nutrients under monoculture may have an advantageous position in the interspecific competition with Skeletonema sp. in the low nutrient environments.