Elodea Canadensis Michx Research Articles

Measuring Chlorophyll a and 14C-Labeled Photosynthate in Aquatic Angiosperms by the Use of a Tissue Solubilizer

A compound that quantitatively correlated with chlorophyll a could be measured fluorometrically in the extracts of leaves of three aquatic angiosperms (Myriophyllum heterophyllum Michx., Potamogeton crispus L., Elodea canadensis Michx.) treated with the tissue solubilizer BTS-450. Fluorescent characteristics of the solubilized plant tissues were stable for several weeks in the dark at temperatures up to 60 degrees C but rapidly degraded in sunlight or when acidified. (14)C-Labeled photosynthate, which had been fixed by leaf discs during 1- to 10-hour exposure to H(14)CO(3), was also readily extracted by the tissue solubilizer. Solubilizer extraction can, therefore, be used to determine both chlorophyll a content and (14)C incorporation rates in the same leaf sample. The method is practical, because no grinding is required, the fluorescent characteristics of the extracts are stable, and analyses can be performed with very little plant material (about 3 milligrams).

Effects of copper chelate on photosynthesis and some enzyme activities of Elodea canadensis

Apical shoots of Elodea canadensis Michx were exposed to different concentrations of Cu(II)—NTA for 21 days in each case; the copper levels used correspond to those in polluted waters of the area. The net assimilation rate of the plants decreased as exposure time and copper concentration increased, whereas the activities of the enzymes, isocitrate dehydrogenase and glutamate dehydrogenase, first increased under slight or moderate stress, but decreased markedly after longer exposure and higher copper levels.

Effects of Low Concentrations of Herbicides on Submersed Aquatic Plants

Laboratory studies were conducted to investigate the possibility that herbicide runoff from treated fields might be adversely affecting submersed aquatic plants in the Chesapeake Bay. In laboratory studies, I1 and I50 values (the concentrations inhibiting growth 1 and 50%, respectively) were calculated for three herbicides and several aquatic plants. Exposure periods varied from 3 to 6 weeks, with the 3-week exposure being most common. For atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], I1 values were usually a few parts per billion (ppb), whereas I50 values varied from ca. 80 ppb for elodea (Elodea canadensis Michx) to ca. 1040 ppb for Eurasian watermilfoil (Myriophyllum spicatum L.). The toxicity of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] was similar to that of atrazine. Glyphosate [N-(phosphonomethyl)glycine] was essentially non-toxic. Interactions between salinity and atrazine were studied using the brackish water species, vallisneria (Vallisneria americana Michx.). Increasing salinity did not affect atrazine toxicity. When atrazine was present in both the hydrosoil and water, the concentration in the water determined the toxicity. At concentrations below 1000 ppb, atrazine in the hydrosoil did not adversely affect the plants. Based on the results of these studies, and the known concentrations of herbicides in runoff water, these herbicides do not appear to pose any threat to the species tested.

Loss of inorganic and organic carbon by 14C-labelled aquatic plants

The loss of inorganic and extracellular organic carbon (EOC) from three 14C-labelled aquatic macrophytes was determined in a flow-through water system. The rates of inorganic 14C loss from Littorella uniflora (L.) Aschers. and Elodea canadensis Michx. during 2 h in the light decreased to 59 and 23% of the initial rates, respectively. The loss rate by Fontinalis antipyretica L. decreased only slightly during 2 h in the light. The rates of inorganic 14C loss in darkness were higher than those in the light. After the initial post-illumination CO 2 burst, the loss rates decreased only slightly in Littorella and Fontanalis`s, but very rapidly in Elodea. The loss of 14C-labelled EOC declined rapidly during the first hour after placing the plants in an unlabelled medium, and then approached almost constant rates. From 15 to 85% of the total EOC could be recovered on a 0.2 μm membrane filter. The particulate fraction was shown to be of direct macrophyte origin. The major portion of the dissolved EOC lost by Littorella had a molecular weight of about 200 and was probably an early photosynthetic product. Due to a decrease in EOC activity with time after placing labelled plants in an unlabelled medium, the use of the 14C labelling technique to measure quantitative loss of EOC must be used in a relative way.

Elodea canadensis and its dormant apices: An investigation of organic and mineral constituents

Some organic and inorganic constituents of Elodea canadensis Michx. and its dormant apices were investigated. Plants collected at a site with a higher phosphate load (0.14 meq PO 4 l −1 daily mean, 0.28 meq l −1 maximum) were characterized by lower starch levels and higher total concentrations of cations, inorganic and organic anions, respectively, as compared with plants from a less eutrophic site. In winter, starch was accumulated in the plants and the concentrations of ionic components decreased markedly. The uniqueness of the dormant apices was demonstrated by very high starch levels and low concentrations of cations, and organic and inorganic anions. Moreover, succinate, a component not present in detectable amounts in the parent plants, made up 3.7% of the total organic anion content.

The influence of environmental factors on apparent photosynthesis and respiration of the submersed macrophyte Elodea canadensis

Abstract Oxygen effects on apparent photosynthetic and dark respiratory O2 exchange rates of detached leaves of Elodea canadensis Michx. (Hydrocharitaceae) were determined over a range of conditions which the submersed plant is likely to experience in shallow water. Apparent photosynthesis is inhibited by O2 under all the experimental regimes of light, temperature, CO2 concentration and pH. This inhibition is not caused solely by an accelerated rate of dark respiration, and the observed variations in O2 inhibition are comparable to O2 effects on photosynthesis and photorespiration of terrestrial C3 plants. Percentage inhibition of apparent photosynthesis is enhanced by high O2 and also by low CO2. These results indicate that high O2, high pH and low CO2 conditions could cause major losses in photosynthetic activity under field conditions. This may account for some of the losses in biomass that are observed under still water conditions.

Nutrient Chemistry in Herbicide‐treated Ponds of Differing Fertility

AbstractPonds 0.04 ha in bottom area and 1.2 m uniform depth with similar densities of the submerged aquatic plant Elodea canadensis Michx. but with different previous nutrient additions were treated with 1 mg/liter diquat (6,7‐dihydrodipyrido [1,2‐a:2′,1′‐c] pyrazinediium ion) on 17 Nov. 1972. This was done to simulate normal weedkill conditions and to measure subsequent carryover effects of past nutrient inputs. Before treatment and for 1 year thereafter, soluble P, particulate P, NO3−, NO2−, NH4+, K+, and chlorophyll a were measured in treated and similar control ponds. After herbicide treatment soluble P concentrations rose dramatically within 24 hours but were reduced to control levels of 10 to 20 µg/liter within 3 weeks. All P forms in the fertilized treated pond remained low until the following June, when particulate and organic P increased to 100 to 300 µg/liter as a result of mineralization processes. Chlorophyll a rose soon after to about 200 µg/liter and NH2+‐N to 100 µg/liter. There were no other differences between control or treated ponds in NH4+ or NO3− concentrations, but both increased several fold each fall in all ponds. Definite carryover effects of previous nutrient inputs were demonstrated in the herbicidetreated ponds, but not in untreated ponds. The compartment in the pond which stored these nutrients and then released them upon herbicide treatment was the rooted macrophytes.

Photosynthesis, respiration, and organic carbon release in Elodea canadensis michx.

Photosynthesis, respiration, and release of organic carbon were examined using 14C in the freshwater angiosperm Elodea canadensis Michx. to investigate ecophysiological implications of recent biochemical evidence for significant levels of C 4 photosynthesis in this plant, a pathway normally associated with low photorespiration and high photosynthetic efficiency. Photosynthetic light saturation level was somewhat high, but not in the normal C 4 range. In morning and afternoon in situ experiments with oxygen manipulations, the plant exhibited an afternoon depression of net photosynthesis suggestive of C 3 performance. Organic carbon release was significant and may have included glycolate, but photorespiration as oxygen-sensitive loss of carbon dioxide in the light was not demonstrable, and the carbon dioxide compensation point was very low and oxygen-insensitive, consistent with C 4 efficiency. Thus the plant, while not a C 4 species, appeared to have some responses consistent with partial operation of the C 4 pathway, which may contribute to the frequent competitive superiority of the plant.

DIFFERENTIAL ENZYME ACTIVITY DURING TRICHOBLAST DIFFERENTIATION IN ELODEA CANADENSIS

Enzymes active in the developing root epidermis of Elodea canadensis Michx. were demonstrated by histochemical techniques. The future root‐hair‐forming cells (trichoblasts) showed a period of elevated activity more extensive than the one previously reported in trichoblasts of another species for dehydrogenases (glucose‐6‐phosphate, pyruvate, lactate, succinic, isocitrate, glutamate), phosphatases (acid, ATPase, 5‐nucleotidase), cytochrome oxidase, and peroxidase. This elevated activity extended from the time of trichoblast formation up to the point of root hair outgrowth, even for enzymes not previously demonstrated in trichoblasts: alkaline phosphatase, NADH diaphorase, NADPH diaphorase, esterase, and leucine aminopeptidase. Glucose‐6‐phosphatase and aryl sulfatase were not detected. The single exception to this pattern was phosphorylase activity, which intensified only just prior to and during root hair outgrowth. The more generalized activity pattern is considered to indicate the so‐called meristematic character of these cells in terms of both macromolecular synthesis and lack of specialization. It is suggested that specific root hair development begins just prior to initiation, at the point marked by elevated phosphorylase activity.

Differential Enzyme Activity During Trichoblast Differentiation in Elodea canadensis

Enzymes active in the developing root epidermis of Elodea canadensis Michx. were demonstrated by histochemical techniques. The future root-hair-forming cells (trichoblasts) showed a period of elevated activity more extensive than the one previously reported in trichoblasts of another species for dehydrogenases (glucose-6-phosphate, pyruvate, lactate, succinic, isocitrate, glutamate), phosphatases (acid, ATPase, 5-nucleotidase), cytochrome oxidase, and peroxidase. This elevated activity extended from the time of trichoblast formation up to the point of root hair outgrowth, even for enzymes not previously demonstrated in trichoblasts: alkaline phosphatase, NADH diaphorase, NADPH diaphorase, esterase, and leucine aminopeptidase. Glucose-6-phosphatase and aryl sulfatase were not detected. The single exception to this pattern was phosphorylase activity, which intensified only just prior to and during root hair outgrowth. The more generalized activity pattern is considered to indicate the so-called meristematic character of these cells in terms of both macromolecular synthesis and lack of specialization. It is suggested that specific root hair development begins just prior to initiation, at the point marked by elevated phosphorylase activity.

Effects of Fertilization on Aquatic Plants, Water, and Bottom Sediments

A 2-year field study was conducted to determine the effects of fertilization on elodea(Elodea canadensisMichx.), eurasian watermilfoil(Myriophyllum spicatumL.), and heartleaf pondweed(Potamogeton pulcherTuckerm.). Plants, water, and sediment were sampled and inorganic mineral contents determined. Water concentrations of NO3, NH4, P, and K increased sharply following fertilization and generally reached maximum values within 7 days after treatment. Concentrations of these nutrients decreased rapidly after reaching maximum values. In the first year, plant growth was not increased due to fertilization while in the second year only heartleaf pondweed produced significantly greater yields. Elodea and eurasian watermilfoil grew better in the control environment, presumably due to less competition from algae, whose growth was increased by the addition of fertilizer. At the end of the study the top 1.3 cm of bottom sediment had increased in cation exchange capacity (C. E. C.), organic matter, total N, and available P for all treatments while the underlying sediment remained relatively unchanged. Available P was greater in the surface of the fertilized sediment than in the surface of the control sediment.

Ecology of Aquatic Vascular Plants in Southern Ontario Impoundments

Aquatic plants and physical-chemical data were collected during 1969 from 19 ponds and lakes. The fertility of these waters, as indicated by specific conductance, appeared to be a function of watershed area over the range 0 to 100 hectares. For watersheds greater than 100 hectares, differences in soil type and farming intensity were major causes of variability. Chara (Charaspp.) was found at specific conductances from 96 to 445 micromhos/sq cm (at 18 C) but was most abundant between 218 and 300. Chara also grew best in the upper half of the transparency range at Secchi disc readings varying from 2.4 to 5.8 m. Elodea (Elodea canadensisMichx.) flourished at specific conductances of 224 to 300 micromhos/sq cm and at transparencies from 2.7 to 5.8 m. Largeleaf pondweed (Potamogeton amplifoliusTuckerm.) was found only in the least fertile impoundment, whereas curlyleaf pondweed (P. crispusL.) occurred only in the most fertile impoundment. Sago pondweed (P. pectinatusL.) occurred at specific conductances of 200 to 349 micromhos/sq cm but was most prolific from 229 upward. This species also favored extensive shallow areas subject to a continuous summer flow.

Effect of Sublethal and Lethal Temperature on Plant Cells

Soybean, Glycine max L., and elodea, Elodea canadensis Michx, leaves were exposed to sublethal and lethal temperatures and examined by light microscopy. Loss of chlorophyll and swollen chloroplasts were observed in cells of elodea leaves exposed to sublethal temperatures. At the thermal death point of leaf cells of elodea and soybean, there was a disorganization of the tonoplast membrane, plasmalemma, and chloroplast membranes. Approximately 40% of the cells in elodea and 50% of the cells in soybean leaves exhibited oriteria of cell death when exposed to a temperature which induced necrotic leaf tissue. Plasmolysis of leaf cells of elodea and soybean occurred at lethal temperatures, but did not appear to be the primary cause of cellular death. The primary effect of lethal temperatures on the leaf cells used in these experiments is disintegration of the cellular membranes.Following exposure of attached elodea leaves to lethal temperatures, changes in leaf cells were periodically observed with a light microscope. In low temperature treatments, (43 through 52 degrees ), the percentages of cells exhibiting criteria of death 12 days after treatment did not change from the percentages determined immediately after treatment. All treatments above 52 degrees resulted in 40% or more of the cells exhibiting criteria of cell death immediately after treatment. In these treatments, this resulted in all cells exhibiting criteria of death on the fourth day after treatment.

Influence of Simazine on Apparent Photosynthesis of Aquatic Plants and Herbicide Residue Removal from Water

Simazine (2-chloro-4,6-bis(ethylamino)-s-triazine) at 0.12 to 1.0 ppmw in nutrient cultures of common duckweed (Lemna minor L.), elodea (Elodea canadensis Michx.), and parrotfeather (Myriophyllum brasiliense Camb.) inhibited oxygen evolution within 24 hr. Of the plants studied, the submersed form of parrotfeather exhibited the greatest reduction in apparent photosynthesis as measured by dissolved oxygen in the water. Simazine in nutrient culture without plants remained relatively stable during the treatment period; a slight, but not significant, diminution of chemical was detected after 4 days. Each species, elodea or emersed parrotfeather, reduced the concentration of simazine in solution within 48 hr after treatment.

Uptake and Translocation of Diquat in Elodea

Uptake and translocation of 6,7-dihydrodipyrido[1,2-a:2′, 1′-c]pyrazidiinium salt (diquat) in elodea (Elodea canadensis Michx) was investigated by autoradiography and counting of plants treated with diquat-14C. Uptake initially was very rapid followed by a slower accumulation of diquat. Part of this uptake was reversible in water and rapidly reached a saturation value while the slower uptake was nonreversible. This reversibility of uptake appears to indicate an initial passive adsorption probably followed by accumulation. Slight basipetal and acropetal movement of diquat was demonstrated with accumulation in the nodes and axillary buds. Movement was unaffected by light versus dark treatments. Diquat injured treated and adjacent untreated shoots of elodea to almost the same extent. This transfer occurred whether or not the treated and untreated shoots were in contact.

The Tetrazolium Reaction as a Measure of the Action of Diquat in Elodea

The production of red triphenyl formazan (hereinafter referred to as TPF) from colorless 2,3,5-triphenyl tetrazolium chloride (hereinafter referred to as TTC) by living cells was used as a vitality indicator for examining the effects of 6,7-dihydrodipyrido[1,2-a:2′,1′-c] pyrazidiinium salt (diquat) in elodea (Elodea canadensisMichx) shoots at varying light intensities. Diquat at 10 ppmw completely killed the elodea in 6 hr at 183 ft-c and at almost the same rate at 13,000 ft-c due to light saturation near the lower level. Over 24 hr were required for this effect in the dark. Between 29 and 183 ft-c, TPF production varied inversely with the light intensity. A comparison is made with the destruction of chlorophyll by diquat.