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Bart A. Nolet - One of the best experts on this subject based on the ideXlab platform.
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Appendix B. Figures showing (1) an overview of the study area and study design; (2) Sago Pondweed tuber biomass densities in the experimental grid; (3) mean Sago Pondweed tuber density for plots in which aboveground biomass was removed during differe
2016Co-Authors: Raymond H. G. Klaassen, Bart A. Nolet, Daniëlle BankertAbstract:Figures showing (1) an overview of the study area and study design; (2) Sago Pondweed tuber biomass densities in the experimental grid; (3) mean Sago Pondweed tuber density for plots in which aboveground biomass was removed during different stages of the growing season; and (4) the mean Sago Pondweed biomass density encountered by a swan when it made short and long movements from patches with different initial tuber density classes
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how a bottom dweller beats the canopy inhibition of an aquatic weed potamogeton pectinatus by macroalgae chara spp
Freshwater Biology, 2010Co-Authors: Bert Hidding, Robert J Brederveld, Bart A. NoletAbstract:1. Bottom-dwelling charophytes have been observed to replace canopy-forming Pondweeds within a few years in de-eutrophied shallow lakes. Competition for bicarbonate (HCO3−) may explain this shift in vegetation dominance but inhibition of Pondweeds by Chara spp. through direct competition has not been shown experimentally. 2. We tested whether charophytes inhibited growth of fennel Pondweed (Potamogeton pectinatus) in the absence of belowground competition by growing plants in pots in mesocosms following a replacement series experimental design. To further understand the role of bicarbonate, we studied main and interactive effects of Chara, light and bicarbonate on P. pectinatus growth in a laboratory study. 3. Early in the mesocosm experiment, high charophyte densities had a negative effect on P. pectinatus cover at a time when bicarbonate levels were low. However, bicarbonate levels eventually converged to low levels in all treatments. At final harvest, both species exhibited lower biomasses at higher densities of conspecific pots, indicating that ultimately intraspecific competition was limiting. In a laboratory study, Chara inhibited P. pectinatus the most under a combination of high light and high bicarbonate concentrations, suggesting that Chara may negatively affect P. pectinatus by acting as a general nutrient sink. 4. Our results suggest that Chara growth can reduce bicarbonate levels, delaying but not preventing a P. pectinatus growth pulse. Given the recorded inhibition under ample bicarbonate supply, Chara’s ability to act as nutrient sink may contribute to the decline of P. pectinatus under Chara recovery in shallow lakes.
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Differences in tolerance of Pondweeds and charophytes to vertebrate herbivores in a shallow Baltic estuary
Aquatic Botany, 2010Co-Authors: Bert Hidding, Elisabeth S. Bakker, Frida Keuper, T. De Boer, P.p. De Vries, Bart A. NoletAbstract:It has been suggested that herbivorous waterfowl may be important in shaping aquatic plant communities in shallow wetlands. As such, a shift from canopy forming Pondweeds to bottom-dwelling charophytes in a formerly turbid Pondweed dominated lake has been partly attributed to waterfowl herbivory. Here we study the separate and combined effects of both belowground herbivory in spring by whooper swans and Bewick ‘s swans, and grazing in summer by waterfowl and fish on the community composition in a shallow Baltic estuary during one year. The macrophyte community was dominated by charophytes (mainly Chara aspera) with Potamogeton pectinatus and Najas marina present as subdominants. Other species were rare. Both spring and summer herbivory had no effect on total plant biomass. However, P. pectinatus was more abundant in plots that were closed to spring and summer herbivores. N. marina was more abundant in grazed plots, whereas Chara spp. biomass remained unaffected. Probably belowground propagules of both C. aspera and P. pectinatus were consumed by swans but since C. aspera bulbils were numerous it may have compensated for the losses. P. pectinatus may not have fully recovered from foraging on tubers and aboveground biomass. Our results are in line with other studies in Chara dominated lakes, which found no effect of grazing on summer aboveground Chara biomass, whereas several studies report strong effects of herbivory in lakes dominated by P. pectinatus.
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The role of herbivorous water birds in aquatic systems through interactions with aquatic macrophytes, with special reference to the Bewick's Swan: Fennel Pondweed system
Hydrobiologia, 2007Co-Authors: Marcel Klaassen, Bart A. NoletAbstract:The role of aquatic macrophytes in stimulating biodiversity and maintaining clear waters is currently undisputed. The management of (eutrophic) shallow waters is therefore often directed at (re-)establishing macrophyte domination. In contrast, the role of water birds has long been considered of minor importance for the functioning of fresh water ecosystems. Indeed, in terms of biomass and production, water birds constitute only a minor part of these systems. However, water birds may graze heavily on water plants under certain circumstances, and the question arises whether herbivorous water birds have an important indirect effect on shallow fresh water systems. Mainly illustrated with the interaction between Bewick’s Swans and Fennel Pondweed, we present data on the role that water plants may play in the life of water birds and how water birds may impact water plants’ fitness in terms of survival, production, dispersal and competitive ability. It appears that water plants may be crucial for water birds during periods of high-energy requirements, such as migration. Despite the plants’ costs associated with water bird grazing, the interaction between water birds and water plants varies in nature from an apparent predator–prey relationship to a mutually beneficial interaction depending on the context and the perspective. For the case of the Bewick’s Swan–Fennel Pondweed interaction, regular bird grazing is sustainable and may actually favour the plant’s dispersal. Thus, Bewick’s Swans themselves may in fact play a crucial role in establishing and maintaining the Fennel Pondweed rich staging sites between the swans’ wintering and breeding grounds, which are vital for the swans’ successful migration.
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overcompensation and grazing optimisation in a swan Pondweed system
Freshwater Biology, 2004Co-Authors: Bart A. NoletAbstract:1. The general notion is that negative effects of vertebrate herbivores on water plants, which play a key role in freshwaters, prevail, and that positive feedbacks of herbivores on plants are insignificant. 2. The most likely systems to find such positive feedbacks are those in which herbivores exert strong feeding pressures on plants during part of the year. Previous theoretical work has suggested that compensatory production occurs when migratory Bewick's swans forage on tubers of fennel Pondweed. As a corollary, the swans can exploit the tubers down to a level that maximises their tuber yield. 3. In order to test these hypotheses, I measured Pondweed tuber biomass on three occasions per year (just before and after foraging, and just before tuber sprouting) in three consecutive years. The 17 sampling sites in the Lauwersmeer (the Netherlands) were classified according to their silt content and water depth. Within four silt-depth classes, I predicted for each year tuber biomass production and, from that, the optimum foraging threshold that would result in the maximum tuber biomass yield 4. Water depth did not affect tuber production, and silt content only did in one of the 3 years. In accordance with overcompensation predictions, tuber production was higher at plots with moderate foraging pressures than at plots with little or no grazing. However, the winter and summer conditions following the swan foraging had large unpredictable effects on tuber mortality and production. 5. These results indicate that overcompensation by fennel Pondweed occurs and that Bewick's swans are generally able to profit from it, albeit without fine-tuning of the foraging threshold to the yield. [KEYWORDS: compensatory production ; foraging threshold ; intraspecific competition ; maximum yield ; sequential model]
Kimiharu Ishizawa - One of the best experts on this subject based on the ideXlab platform.
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involvement of plasma membrane h atpase in anoxic elongation of stems in Pondweed potamogeton distinctus turions
New Phytologist, 2011Co-Authors: Yayoi Koizumi, Yoshinao Hara, Yoshiaki Yazaki, Katsuhiro Sakano, Kimiharu IshizawaAbstract:Summary •Pondweed (Potamogeton distinctus) turions can elongate in the absence of O2. Alcoholic fermentation serves to produce energy for anoxic elongation via the breakdown of starch stored in cells. However, the mechanism of cell growth during anoxic elongation is not fully understood. •Changes in pH, H+ equivalent and lactate content of the incubation medium were measured during anoxic elongation. The effects of fusicoccin (FC), indole-3-acetic acid (IAA), vanadate, erythrosine B and K+ channel blockers on anoxic elongation were examined. Cytoplasmic pH and vacuolar pH were measured by 31P nuclear magnetic resonance (NMR) spectroscopy. •Acidification of the incubation medium occurred during anoxic elongation. The contribution of CO2 and lactic acid was not sufficient to explain the acidification. FC and IAA enhanced the elongation of stem segments. Vanadate and erythrosine B inhibited anoxic elongation. Acid growth of notched segments was observed. The activity of plasma membrane H+-ATPase extracted from Pondweed turions was increased slightly in anoxic conditions, but that from pea epicotyls sensitive to anoxic conditions was decreased by incubation in anoxic conditions. Both the cytoplasmic pH and vacuolar pH of Pondweed turion cells chased by 32P NMR spectroscopy were stabilized during a short period < 3 h after anoxic conditions. •We propose that the enhancement of H+ extrusion by anoxic conditions induces acidification in the apoplast and may contribute to the stabilization of pH in the cytoplasm.
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Involvement of plasma membrane H+‐ATPase in anoxic elongation of stems in Pondweed (Potamogeton distinctus) turions
The New phytologist, 2011Co-Authors: Yayoi Koizumi, Yoshinao Hara, Yoshiaki Yazaki, Katsuhiro Sakano, Kimiharu IshizawaAbstract:Summary •Pondweed (Potamogeton distinctus) turions can elongate in the absence of O2. Alcoholic fermentation serves to produce energy for anoxic elongation via the breakdown of starch stored in cells. However, the mechanism of cell growth during anoxic elongation is not fully understood. •Changes in pH, H+ equivalent and lactate content of the incubation medium were measured during anoxic elongation. The effects of fusicoccin (FC), indole-3-acetic acid (IAA), vanadate, erythrosine B and K+ channel blockers on anoxic elongation were examined. Cytoplasmic pH and vacuolar pH were measured by 31P nuclear magnetic resonance (NMR) spectroscopy. •Acidification of the incubation medium occurred during anoxic elongation. The contribution of CO2 and lactic acid was not sufficient to explain the acidification. FC and IAA enhanced the elongation of stem segments. Vanadate and erythrosine B inhibited anoxic elongation. Acid growth of notched segments was observed. The activity of plasma membrane H+-ATPase extracted from Pondweed turions was increased slightly in anoxic conditions, but that from pea epicotyls sensitive to anoxic conditions was decreased by incubation in anoxic conditions. Both the cytoplasmic pH and vacuolar pH of Pondweed turion cells chased by 32P NMR spectroscopy were stabilized during a short period
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Anoxia-enhanced expression of genes isolated by suppression subtractive hybridization from Pondweed ( Potamogeton distinctus A. Benn.) turions
Planta, 2007Co-Authors: Taro Harada, Shigeru Satoh, Toshihito Yoshioka, Kimiharu IshizawaAbstract:Pondweed (Potamogeton distinctus A. Benn.), a monocot aquatic plant species, has turions, which are overwintering buds forming underground as an asexual reproductive organ. Turions not only survive for more than one month but also elongate under strict anoxia, maintaining high-energy charge by activation of fermentation. We cloned 82 cDNA fragments of genes, that are up-regulated during anoxic growth of Pondweed turions, by suppression subtractive hybridization. The transcript levels of 44 genes were confirmed to be higher under anoxia than those in air by both Northern blot analysis and a semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) method. A homology search for their nucleotide sequences revealed that some of them are highly homologous to known sequences of genes from other plants. They included alcohol dehydrogenase, pyruvate decarboxylase (PDC), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), vacuolar H+-translocating pyrophosphatase and a plasma membrane intrinsic protein. Time courses of transcript accumulation of some genes under anoxia were different from those in air. The activity of PDC increased under anoxic conditions but the activities of GAPDH and pyrophosphatase remained constant after anoxic treatment. Anoxically up-regulated genes are possibly involved in physiological events to control energy production, pH regulation and cell growth under anoxia. These results suggest that transcriptional regulation of these genes serves as an essential part of survival and growth of Pondweed turions under anoxia.
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expression of sucrose synthase genes involved in enhanced elongation of Pondweed potamogeton distinctus turions under anoxia
Annals of Botany, 2005Co-Authors: Taro Harada, Kimiharu Ishizawa, Shigeru Satoh, Toshihito YoshiokaAbstract:� Background and Aims Overwintering buds (turions) of the monocot aquatic Pondweed species (Potamogeton distinctus) are highly tolerant to anoxic stress. Sucrose metabolism accompanied by enhanced activity of sucrose synthase (SuSy) operates actively during anaerobic elongation of Pondweed turions. The aim of this study is to isolate SuSy genes from the turions and to investigate their transcriptional changes in response to anoxia and other stimuli. � Methods SuSy genes were isolated from Pondweed turions by PCR methods and transcript levels of SuSy genes were examined in response to anoxia, sugars and plant hormones. In addition, the effects of anoxia on SuSy activity were examined both in the soluble fraction and in the microsomal fraction. � Key Results cDNAs of two SuSy genes (PdSUS1 and PdSUS2) were cloned from Pondweed turions. The levels of PdSUS1 transcripts increased under anoxia but did not with sugar treatments. Anoxia-stimulated elongation of turions was further enhanced by 2,4-dichlorophenoxyacetic acid (2,4-D) and suppressed by treatments with sorbitol, 2-deoxyglucose (2-dGlc) and abscisic acid (ABA). The levels of PdSUS1 transcripts were increased by 2,4-D and decreased by sorbitol under anoxia. The levels of PdSUS2 transcripts were not significantly affected by anoxia and any other treatments. SuSy activity of turions under anoxia was enhanced in the soluble fraction, but not in the microsomal fraction. � Conclusions Up-regulation of PdSUS1 transcription under anoxia may not be attributed to sugar starvation under anoxia. A positive correlation between stem elongation and the level of PdSUS1 transcripts was observed in turions treated with anoxic conditions, 2,4-D and sorbitol. The increase in SuSy activity in the cytosol may contribute to sugar metabolism and sustain stem elongation under anoxia.
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Starch degradation and sucrose metabolism during anaerobic growth of Pondweed (Potamogeton distinctus A. Benn.) turions
Plant and Soil, 2003Co-Authors: Taro Harada, Kimiharu IshizawaAbstract:Stem growth in Pondweed (Potamogeton distinctus A. Benn.) turions was stimulated in anaerobic conditions. Decreases in starch contents in turion cells, the number of amyloplasts in a cell and sizes of starch granules in amyloplasts clearly showed enhancement of starch consumption in turions during anaerobic growth of stems of Pondweed. Although the total activities of both α-amylase and starch phosphorylase were not stimulated by anaerobic conditions, the activities of one amylase and two isozymes of starch phosphorylase, separated by native polyacrylamide gel electrophoresis, were enhanced in anaerobic conditions. The sucrose content in turion cells decreased rapidly in the early stage of anaerobic growth but then remained constant after the enhanced growth had started, suggesting active sucrose metabolism. The activities of sucrose-phosphate synthase, sucrose synthase and acid invertase, measured in vitro, were enhanced in extracts from turions in anaerobic conditions. The induction of the activity of sucrose synthase was most significant, suggesting that sucrose synthase plays an important role in sucrose metabolism in Pondweed turions growing in anaerobic conditions.
P. Pardha-saradhi - One of the best experts on this subject based on the ideXlab platform.
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Differential Response of Floating and Submerged Leaves of Longleaf Pondweed to Silver Ions.
Frontiers in plant science, 2017Co-Authors: Nisha Shabnam, P. Sharmila, Govindjee, Hyunook Kim, P. Pardha-saradhiAbstract:In this study, we have investigated variations in the potential of floating and submerged leaves of longleaf Pondweed (Potamogeton nodosus) to withstand silver ion (Ag+)-toxicity. Both floating and submerged leaves changed clear colorless AgNO3 solutions to colloidal brown in the presence of light. Transmission electron microscopy revealed the presence of distinct crystalline Ag-nanoparticles (Ag-NPs) in these brown solutions. Powder X-ray diffraction pattern showed that Ag-NPs were composed of Ag0 and Ag2O. Photosystem (PS) II efficiency of leaves declined upon exposure to Ag+; with a significantly higher decline in the submerged leaves than in the floating leaves. Similarly, Ag+ treatment caused a significant reduction in the carboxylase activity of the ribulose bisphosphate carboxylase/oxygenase in leaves. The reduction in this carboxylase activity was significantly higher in the submerged than in the floating leaves. Ag+ treatment also resulted in a significant decline in the levels of non-enzymatic and enzymatic antioxidants; the decline was significantly lower in the floating than in submerged leaves. X-ray photoelectron spectroscopy revealed the presence of Ag2O in these leaves. Inductively coupled plasma mass spectrometry analysis revealed a three-fold higher Ag content in the submerged than in floating leaves. Our study demonstrates that floating leaves of longleaf Pondweed have a superior potential to counter Ag+-toxicity compared with submerged leaves, which could be due to the superior potential of floating leaves to reduce Ag+ to less/non-toxic Ag0/Ag2O-nanoparticles/nanocomplexes. We suggest that modulating the genotype of longleaf Pondweed to bear higher proportion of floating leaves would help in cleaning fresh water bodies contaminated with ionic forms of heavy metals.
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Differential Response of Floating and Submerged Leaves of Longleaf Pondweed to Silver Ions
Frontiers Media S.A., 2017Co-Authors: Nisha Shabnam, P. Sharmila, Hyunook Kim, P. Pardha-saradhiAbstract:In this study, we have investigated variations in the potential of floating and submerged leaves of longleaf Pondweed (Potamogeton nodosus) to withstand silver ion (Ag+)-toxicity. Both floating and submerged leaves changed clear colorless AgNO3 solutions to colloidal brown in the presence of light. Transmission electron microscopy revealed the presence of distinct crystalline Ag-nanoparticles (Ag-NPs) in these brown solutions. Powder X-ray diffraction pattern showed that Ag-NPs were composed of Ag0 and Ag2O. Photosystem (PS) II efficiency of leaves declined upon exposure to Ag+ with a significantly higher decline in the submerged leaves than in the floating leaves. Similarly, Ag+ treatment caused a significant reduction in the carboxylase activity of the ribulose bisphosphate carboxylase/oxygenase in leaves. The reduction in this carboxylase activity was significantly higher in the submerged than in the floating leaves. Ag+ treatment also resulted in a significant decline in the levels of non-enzymatic and enzymatic antioxidants; the decline was significantly lower in the floating than in submerged leaves. X-ray photoelectron spectroscopy revealed the presence of Ag2O in these leaves. Inductively coupled plasma mass spectrometry analysis revealed a three-fold higher Ag content in the submerged than in floating leaves. Our study demonstrates that floating leaves of longleaf Pondweed have a superior potential to counter Ag+-toxicity compared with submerged leaves, which could be due to superior potential of floating leaves to reduce Ag+ to less/non-toxic Ag0/Ag2O-nanoparticles/nanocomplexes. We suggest that modulating the genotype of longleaf Pondweed to bear higher proportion of floating leaves would help in cleaning fresh water bodies contaminated with ionic forms of heavy metals
Kurt D Getsinger - One of the best experts on this subject based on the ideXlab platform.
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Early-season, Low-dose Applications of Endothall to Selectively Control Curlyleaf Pondweed in Minnesota Lakes
2008Co-Authors: John G. Skogerboe, Kurt D Getsinger, Angela G Poovey, Wendy Crowell, Eric MacbethAbstract:Abstract : This multi-year study was designed to evaluate early spring applications of low doses of endothall to selectively control the invasive submersed plant curlyleaf Pondweed (Potamogeton crispus L.) in Minnesota lakes.
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concentration exposure time relationships for controlling sago Pondweed stuckenia pectinata with endothall
Weed Technology, 2008Co-Authors: Jeremy G. Slade, Angela G Poovey, Kurt D GetsingerAbstract:The submersed macrophyte, sago Pondweed, frequently grows to nuisance levels in water conveyance systems throughout the western United States and can cause problems in lakes, reservoirs, and other water bodies. The liquid dipotassium and dimethylalkylamine salt formulations of endothall were evaluated for controlling sago Pondweed using short exposure times (3 to 24 h) under controlled environmental conditions (14 : 10 h light : dark; 21.5 C). Endothall treatments ranged from 1 to 10 mg ai/L (dipotassium salt) and 0.5 to 5 mg ae/L (dimethylalkylamine salt). Sixteen concentration and exposure time (CET) combinations were evaluated in each study. At 4 wk after treatment, all CET combinations significantly reduced shoot biomass (43 to 99%) of sago Pondweed compared with the untreated reference. Reduction in shoot biomass was greater in plants that received higher herbicide doses and longer exposure times. In addition, more than half of the endothall CET combinations controlled sago Pondweed by at least 90%, ...
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Concentration–Exposure Time Relationships for Controlling Sago Pondweed (Stuckenia pectinata) with Endothall
Weed Technology, 2008Co-Authors: Jeremy G. Slade, Angela G Poovey, Kurt D GetsingerAbstract:The submersed macrophyte, sago Pondweed, frequently grows to nuisance levels in water conveyance systems throughout the western United States and can cause problems in lakes, reservoirs, and other water bodies. The liquid dipotassium and dimethylalkylamine salt formulations of endothall were evaluated for controlling sago Pondweed using short exposure times (3 to 24 h) under controlled environmental conditions (14 : 10 h light : dark; 21.5 C). Endothall treatments ranged from 1 to 10 mg ai/L (dipotassium salt) and 0.5 to 5 mg ae/L (dimethylalkylamine salt). Sixteen concentration and exposure time (CET) combinations were evaluated in each study. At 4 wk after treatment, all CET combinations significantly reduced shoot biomass (43 to 99%) of sago Pondweed compared with the untreated reference. Reduction in shoot biomass was greater in plants that received higher herbicide doses and longer exposure times. In addition, more than half of the endothall CET combinations controlled sago Pondweed by at least 90%, ...
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Selective control of Eurasian watermilfoil and curlyleaf Pondweed using low doses of endothall combined with 2,4-D
2006Co-Authors: John G. Skogerboe, Kurt D GetsingerAbstract:Abstract : This study was designed to evaluate early spring applications of low doses of endothall (1 mg/L ai) combined with 2,4-D (0.5 mg/L ai) to selectively control the invasive species curlyleaf Pondweed (Potamogeton crispus L) and Eurasian watermilfoil (Myriophyllum spicatum L) in Minnesota lakes.
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mesocosm evaluation of the species selective potential of fluridone
1997Co-Authors: M D Netherland, Kurt D Getsinger, J D SkogerboeAbstract:Fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl) phenyl]-4(1H)-pyridinone} was evaluated at rates of 0, 5, 10, and 20 µ g/L in 6,700-L outdoor mesocosm tanks for selective control of the exotic species Eurasian watermilfoil ( Myriophyllum spicatum L) . Non-target species included elodea ( Elodea canadensis Michaux) , American Pondweed ( Potamogeton nodosus Poiret) , sago Pondweed ( Potamogeton pectinatus L) , and vallisneria ( Vallisneria americana Michaux) . Throughout the study, untreated mesocosms were dominated by Eurasian watermilfoil and elodea with limited growth of vallisneria and the two Pondweed species. Fluridone treatments were conducted on April 23 and May 23 1995 to determine if plant growth stage affected species selectivity. Fluridone residues were monitored in water and target concentrations were achieved with a measured fluridone half-life of 33 days. The 5 µ g/L treatments in April (90 days of exposure) and May (60 days of exposure) reduced biomass of Eurasian watermilfoil by > 90% in late July, while biomass of non-target species generally exceeded the levels of untreated reference plants. Treatments of 10 and 20 µ g/L also reduced Eurasian watermilfoil biomass by > 90%; however, these application rates also reduced growth several non-target species by > 90%. Chara (Chara spp.) and southern naiad ( Najas guadalupensis (Sprengel) Magnus) propagules sprouted and attained high levels of biomass in mesocosms treated at 10 and 20 µ g/L. With the notable exception of vallisneria, plants exposed to 10 and 20 µ g/L in April (90 day exposure) did not show potential for recovery when placed in untreated water for 40 days. In contrast, when transferred to untreated water all species (with the exception of sago Pondweed) exposed to 5, 10, and 20 µ g/L in May (60 day exposure) recovered significantly in comparison to plants that remained exposed to low concentrations of fluridone (1 to 4 µ g/L). Results suggest that fluridone can selectively control Eurasian watermilfoil; however, initial treatment rate, length of exposure, and initial biomass of the plants are key factors. The range of fluridone concentrations that provide selective control of Eurasian watermilfoil in a mixed plant community may be quite narrow.
Nisha Shabnam - One of the best experts on this subject based on the ideXlab platform.
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Differential Response of Floating and Submerged Leaves of Longleaf Pondweed to Silver Ions.
Frontiers in plant science, 2017Co-Authors: Nisha Shabnam, P. Sharmila, Govindjee, Hyunook Kim, P. Pardha-saradhiAbstract:In this study, we have investigated variations in the potential of floating and submerged leaves of longleaf Pondweed (Potamogeton nodosus) to withstand silver ion (Ag+)-toxicity. Both floating and submerged leaves changed clear colorless AgNO3 solutions to colloidal brown in the presence of light. Transmission electron microscopy revealed the presence of distinct crystalline Ag-nanoparticles (Ag-NPs) in these brown solutions. Powder X-ray diffraction pattern showed that Ag-NPs were composed of Ag0 and Ag2O. Photosystem (PS) II efficiency of leaves declined upon exposure to Ag+; with a significantly higher decline in the submerged leaves than in the floating leaves. Similarly, Ag+ treatment caused a significant reduction in the carboxylase activity of the ribulose bisphosphate carboxylase/oxygenase in leaves. The reduction in this carboxylase activity was significantly higher in the submerged than in the floating leaves. Ag+ treatment also resulted in a significant decline in the levels of non-enzymatic and enzymatic antioxidants; the decline was significantly lower in the floating than in submerged leaves. X-ray photoelectron spectroscopy revealed the presence of Ag2O in these leaves. Inductively coupled plasma mass spectrometry analysis revealed a three-fold higher Ag content in the submerged than in floating leaves. Our study demonstrates that floating leaves of longleaf Pondweed have a superior potential to counter Ag+-toxicity compared with submerged leaves, which could be due to the superior potential of floating leaves to reduce Ag+ to less/non-toxic Ag0/Ag2O-nanoparticles/nanocomplexes. We suggest that modulating the genotype of longleaf Pondweed to bear higher proportion of floating leaves would help in cleaning fresh water bodies contaminated with ionic forms of heavy metals.
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Differential Response of Floating and Submerged Leaves of Longleaf Pondweed to Silver Ions
Frontiers Media S.A., 2017Co-Authors: Nisha Shabnam, P. Sharmila, Hyunook Kim, P. Pardha-saradhiAbstract:In this study, we have investigated variations in the potential of floating and submerged leaves of longleaf Pondweed (Potamogeton nodosus) to withstand silver ion (Ag+)-toxicity. Both floating and submerged leaves changed clear colorless AgNO3 solutions to colloidal brown in the presence of light. Transmission electron microscopy revealed the presence of distinct crystalline Ag-nanoparticles (Ag-NPs) in these brown solutions. Powder X-ray diffraction pattern showed that Ag-NPs were composed of Ag0 and Ag2O. Photosystem (PS) II efficiency of leaves declined upon exposure to Ag+ with a significantly higher decline in the submerged leaves than in the floating leaves. Similarly, Ag+ treatment caused a significant reduction in the carboxylase activity of the ribulose bisphosphate carboxylase/oxygenase in leaves. The reduction in this carboxylase activity was significantly higher in the submerged than in the floating leaves. Ag+ treatment also resulted in a significant decline in the levels of non-enzymatic and enzymatic antioxidants; the decline was significantly lower in the floating than in submerged leaves. X-ray photoelectron spectroscopy revealed the presence of Ag2O in these leaves. Inductively coupled plasma mass spectrometry analysis revealed a three-fold higher Ag content in the submerged than in floating leaves. Our study demonstrates that floating leaves of longleaf Pondweed have a superior potential to counter Ag+-toxicity compared with submerged leaves, which could be due to superior potential of floating leaves to reduce Ag+ to less/non-toxic Ag0/Ag2O-nanoparticles/nanocomplexes. We suggest that modulating the genotype of longleaf Pondweed to bear higher proportion of floating leaves would help in cleaning fresh water bodies contaminated with ionic forms of heavy metals
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REGULAR PAPER
2014Co-Authors: Nisha Shabnam, P. Sharmila, Anuradha SharmaAbstract:Mitochondrial electron transport protects floating leaves of long leaf Pondweed (Potamogeton nodosus Poir) against photoinhibition: comparison with submerged leave