• Journal of Ecology and Environment
• /
• 제42권1호
• /
• pp.43-49
• /
• 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
• /
• 제32권2호
• /
• pp.139-153
• /
• 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
• /
• 제32권2호
• /
• pp.97-111
• /
• 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.

• 대한지역사회영양학회지
• /
• 제22권6호
• /
• pp.495-506
• /
• 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.

• 한국식물병리학회:학술대회논문집
• /
• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
• /
• pp.104.1-104
• /
• 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
• /
• 제43권3호
• /
• pp.308-312
• /
• 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.

• 한국산림과학회지
• /
• 제86권1호
• /
• pp.1-8
• /
• 1997

뉴질랜드 북섬의 다우지역에서 라디아타소나무 유묘생장이 일련의 주요 잡초종과의 경쟁으로 인하여 감소함을 계량화(計量化)하기 위하여 계획된 실험의 2차년도 결과이다. 라디아타소나무 유묘(1/0)들을 각각 잡초제거구와 활엽성초본, 목초, broom, pampas, buddleia, gorse와 함께 생육시켰다. 양료와 수분공급은 각 요인에 관수와 시비, 무관수와 무시비로 다양화하였다. 식재 21개월 후 라디아타소나무 유묘의 재적생장량은 잡초제거구와 gorse와 함께 생육된 구에서 최대였고 buddleia나 pampas와 함께 생육된 곳에서는 최소였다. 유묘생장에 대한 잡초의 영향이 수분이나 양료 경쟁에 의해 조정된다는 증거가 없었다. 유묘를 능가하여 치솟는 키크고 빨리 자라는 종(broom, buddleia, pampas)들이 유묘 생장에 가장 큰 영향력을 갖고 있고 그 영향력의 크기는 유묘 위에 뒤덮는 정도와 상관관계가 있었다. 이것은 피음 혹은 광경쟁이 아마도 중요한 인자임을 암시해 주고 있다.

• 한국수산과학회지
• /
• 제42권6호
• /
• pp.674-682
• /
• 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.

• 한국환경과학회지
• /
• 제14권9호
• /
• pp.873-879
• /
• 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.

• 한국해양학회지:바다
• /
• 제19권4호
• /
• pp.232-242
• /
• 2014

본 연구는 유해 와편모조류 Cochlodinium polykrikoides와 규조류 Skeletonema sp.의 용존 유기 영양염에 대한 이용 및 흡수능력을 통해서 종간 경쟁관계를 파악하였다. C. polykrikoides와 Skeletonema sp.는 용존 무기 질소와 무기인 이외에 다양한 용존 유기 질소와 유기 인을 이용하여 성장하였다. 이는 용존 무기 질소 또는 무기 인이 제한 영양염으로 작용하는 환경에서 중요한 생존전략으로 작용할 것이다. Urea와 glycerophospahte(glycero-P)의 흡수동력학 실험으로부터 도출된 반포화상수(Ks) 값은 C. polykrikoides가 Skeletonema sp.에 비해서 낮은 값을 보였다. 이는 Skeletonema sp.가 C. polykrikoides에 비해서 urea와 glycero-P와 같은 유기 영양염에 대한 친화성이 높음을 의미한다. 하지만 Skeletonema sp.가 유기 영양염에 대한 친화성이 높을지라도 C. polykrikoides가 ${\alpha}$ (${\rho}_{max}/Ks$) 값이 높아, 저농도의 영양염 조건(