Download or read book Growth and Rooting Depth Characteristics of Hydrilla Verticillata L f Royle and Myriophyllum Spicatum L on Fertilized and Unfertilized Sediments written by Dwilette G. McFarland and published by . This book was released on 1994 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aquatic Plant Control Research Program Growth and Rooting Depth Characteristics of Hydrilla Verticillata L f Royle and Myriophyllum Spicatum L on Fertilized and Unfertilized Sediments written by and published by . This book was released on 1994 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a series of controlled greenhouse experiments, growth and rooting depth characteristics of Hydrilla verticillata (L.f.) Royle and Myriophyllum spicatum L. were examined relative to sediment-N availability, over a range of sediment depths from 10 to 60 cm. Each species was grown separately on fine- textured, inorganic sediment, either amended with ammonium chloride (N-amended) or rendered N-poor due to previous support of submersed macrophyte growth (nonamended). For both species, diminished biomass production was accompanied by increased root-to-shoot ratios and increased rooting depth (to 60 cm) on nonamended sediment. High production levels in Myriophyllum and Hydrilla on N- amended sediment were unaffected by sediment depth, indicating (along with high tissue N concentrations) that the availability of N under those conditions was nonlimiting. With increased depth of nonamended sediment, both Hydrilla and Myriophyllum increased production and mitigated N-deficiency in plant tissues by increasing root accession of this nutrient from greater sediment depths. This ability, speculated here to be more or less developed in other macrophyte species, may affect the outcome of interspecific interactions, particularly when N concentrations in sediment are low. Aquatic plants, Nitrogen, Sediment composition, Hydrilla, Nutrient limitation, Sediment nutrient availability, Myriophyllum, Nutrient uptake, Submersed macrophytes.

Download or read book Growth and Rooting Depth Characteristics of Hydrilla Verticillata L f Royle and Myriophyllum Spicatum L on Fertilized and Unfertilized Sediments written by Dwilette G. McFarland and published by . This book was released on 1994 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aquatic Plant Control Research Program Feasibility of Relating Phenology and Carbohydrate Partitioning to Improve Aquatic Plant Control written by George J. Pesacreta and published by . This book was released on 1988 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phenology and carbohydrate literature for waterhyacinth (Eichhornia crassipes (Mart.) Solms), hydrilla (Hydrilla verticillata L.f. Royle), Eurasian watermilfoil (Myriophyllum spicatum L.), and alligatorweed (Alternanthera philoxeroides (Mart.) Griesb) was surveyed to assess the feasibility of using phenology/carbohydrate relationships for improving control tactics. Many studies have examined phenology of waterhyacinth, hydrilla, and Eurasian watermilfoil, but not alligatorweed. Phenology of monoecious and dioecious biotypes of hydrilla differs in growth pattern and propagule development. The monoecious biotype appears to be better adapted than the dioecious biotype to live at Northern latitudes because of its ability to produce more tubers and turions at lower water temperatures. A few investigations involving Eurasian watermilfoil and alligatorweed suggested that control efforts directed at the low ebb of carbohydrates will decrease biomass production. Little information on carbohydrate partitioning has been reported for waterhyacinth and hydrilla. Previous studies of these plants have not evaluated the role of starch reserves for plant survival. Environmental factors (e.g., temperature, light, and nutrients) have been shown to influence phenology and, by inference, carbohydrate partitioning. How these factors control carbohydrate partitioning in these plants is unknown. Phenological and carbohydrate relationships have not been fully developed to allow plant control programs to take advantage of weak points in a plant's life cycle. Keywords: Weed control; Aquatic weeds. (KT).

Download or read book Aquatic Plant Control Research Program Effects of Organic Amendments to Sediment on Freshwater Macrophyte Growth written by J. W. Barko and published by . This book was released on 1983 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growth of three submersed macorphyte species (Myriophyllum spicatum, Hydrilla verticillata, and Elodea canadensis) and three partially emergent macrophyte species (Sagittaria latifolia, Myriophyllum aquaticum, and Potamogeton nodosus) was examined on a nonamended sediment and on the same sediment amended by additions of five types of vegetative organic matter (two labile and three refractory). With individual amendments, the organic content of the sediment was increased from an initial value of ca. 10 percent to a final value of 15 percent (low-level amendment) and from an initial value of ca. 15 percent to a final value of 20, 25, and 30 percent (high-level amendments). At equal levels of organic matter addition (low-level amendment), macrophyte growth varied with the type of amendment and the species of aquatic macrophyte. Biomass accrual by emergent species as a group was generally greater on all sediments, and was less inhibited than that of submersed species on amended sediments. At the high levels of amendment, the growth of representative submersed and emergent species was severely inhibited on all amended sediments irrespective of amendment type. The inhibitory influence of Hydrilla verticillata of sediment amended by additions of labile organic matter decreased with increasing sediment age relative to time of amendment.

Download or read book Aquatic Plant Control Research Program Effects of Water Chemistry on Aquatic Plants Interactive Effects of Inorganic Carbon and Nitrogen on Biomass Production and Plant Nutrition written by R. M. Smart and published by . This book was released on 1990 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growth of submersed Egeria densa, Hydrilla verticillata, and Myriophyllum spicatum was examined under 2 levels of inorganic carbon supply, at 2 sediment nitrogen levels, in a solution containing moderate levels of major cations and inorganic carbon. The study's primary objective was to evaluate the interactive effects of inorganic carbon supply and sediment N availability on plant growth and nutrition. Results indicate that both inorganic carbon supply and sediment N availability can limit growth of submersed aquatic plant populations. Egeria was more affected by inorganic carbon supply, Myriophyllum was more affected by sediment N availability, and Hydrilla was equally affected by both factors. Maximal plant growth of all species occurred under conditions of high inorganic carbon supply and high sediment N availability, indicating that suboptimal levels of either factor can depress growth. The results suggest the existence of a feedback loop regulating biomass production in submersed aquatic plants. Increases in the supply of either limiting factor may result in increased demand for the other factor, eventually resulting in low levels of both factors.

Download or read book Effects of Sediment Nitrogen Availability and Plant Density on Interactions Between the Growth of Hydrilla Verticillata and Potamogeton Americanus Aquatic Plant Control Research Program written by and published by . This book was released on 1991 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study examines the growth of Hydrilla verticillata (L.f) Royle and Potamogeton americanus C. and S. on both nitrogen-poor and nitrogen-rich sediments and assesses the nature and degree of interspecific interactions between the two species. Extensive greenhouse experiments conducted from May through July 1989 employed sediments differing initially only in sediment nitrogen (fertilized containers: 0.21 + or - 0.01 mg exchangeable N per gram dry sediment; unfertilized containers: 0.01 + or -0.00 mg exchangeable N per gram dry sediment). Species were grown monotypically, as well as in 50:50 mixtures, on each sediment type. Although shoot production did not differ between species in monoculture, shoot production in Hydrilla was diminished by 60 to 76 percent in the presence of Potamogeton. Likewise, canopy development for Hydrilla was reduced in mixtures compared to monocultures, but Potamogeton did not show a similar reduction in canopy. High sediment nitrogen increased canopy development by 50 percent in both species. Above-ground biomass for monotypically grown species was similarly low on unfertilized sediment (6 to 8 g per container). However, on fertilized sediment, aboveground biomass in Potamogeton (approaching 25 g per container) was significantly greater than in Hydrilla (approximately 15 g per container). Aquatic plants, Macrophyte, Biomass, Nitrogen, Density, Production, Interspecific interaction, Sediment.

Download or read book Government Reports Annual Index written by and published by . This book was released on 1995 with total page 1218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1994-11 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aquatic Plant Control Research Program Interactions Between Macrophyte Growth and Sediment Nutrient Availability written by John W. Barko and published by . This book was released on 1988 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aquatic macrophytes rely primarily on sediment as a direct source of nitrogen (N) and phosphorus (P). The availability of these nutrients in sediments is affected markedly by sediment type, and is also influenced by macrophyte growth. On sediments planted with Hydrilla verticillata Royal compared with control (unplanted) sediment, reductions of>90 percent and>30 percent in concentrations of exchangeable N and extractable P were measured during two 6-week periods of growth. Diminished N availability in sediments due to uptake by Hydrilla resulted in nutrient limitation of subsequent Hydrilla growth. Concomitant increases (>30 percent) in the concentration of exchangeable potassium (K) suggest that this element, obtained via foliar uptake from overlying water, may be exchanged by macrophyte roots for ammonium in sediment. Exchange of K for ammonium in sediments occurred only under conditions of N limitation in this species. Variations in the abilities of different aquatic macrophyte species to deplete sediment nutrients and to contend with autogenic reductions in nutrient availability may have an important influence on successional development in aquatic macrophyte communities and also may potentially affect element exchanges with overlying water.

Download or read book Aquatic Plant Control Research Program Biological Control of Hydrilla Verticillata L f Royle with Lytic Enzyme Producing Microorganisms written by Judith C. Pennington and published by . This book was released on 1985 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bacteria and fungi isolated from the microsphere of hydrilla were screened for production of the lytic enzymes cellulase and pectinase. Lytic enzyme-positive isolates were successively subcultured on restrictive media in the laboratory to enhance enzyme production. Twenty-two of the enzyme-enhanced isolates were assayed using hydrilla sprigs in test tubes to determine their ability to infect the plant. Seven cellulase-producing fungi produced significantly greater damage to hydrilla than exhibited by treated or untreated controls. Six of these were assayed using hydrilla plants in 75.7-l aquaria. None of the fungi significantly damaged hydrilla in the aquaria. Inoculum for the aquarium assay consisted of filtered organisms, whereas whole inoculum including nutrient growth medium (PDB) and accumulated exogenous metabolites (e.g. cellulase) was used in the preliminary test tube assay. This difference in inoculum for the two assays and the negative results of the aquarium assay suggested that the isolates required nutrient or metabolite supplements in the inoculum to inflict damage on hydrilla. Results showed that whole inoculum produced significantly greater damage than filtered organisms and that nutrients must be present for the organisms to impact hydrilla. Results of the two assays also showed that greenhouse plants were more resistant to attack than field plants.

Download or read book Interactions Between Macrophyte Growth and Sediment Nutrient Availability written by and published by . This book was released on 1988 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aquatic Plant Control Research Program Pilot Study Carbohydrate Allocation in Hydrilla Biotypes written by George J. Pesacreta and published by . This book was released on 1990 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbohydrate allocation in monoecious and dioecious hydrilla (Hydrilla verticillata (L.f) Royle) was examined under various water temperature and photoperiod regimes. Propagule production of monoecious hydrilla was also evaluated under different shoot-cutting treatments. Both hydrilla biotypes accumulated starch (35 percent) in shoots under short photoperiods, but only monoecious plants were able to form tubers and turions. High temperature (35 C) promoted fragmentation in both biotypes after 8 weeks of growth. Cutting to 1-cm height decreased shoot starch content and inhibited tuber production in monoecious hydrilla. Shoot removal as a possible means of decreasing propagule formulation in monoecious hydrilla is suggested.

Download or read book Effects of Sediment Composition on Growth of Submersed Aquatic Vegetation written by John W. Barko and published by . This book was released on 1986 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments with two submersed aquatic macrophytes, Myriophyllum spicatum L. and Hydrilla verticillata (L.f.) Royle, grown on 40 different sediments from 17 geographically widespread North American lakes, indicated tenfold and twentyfold declines in growth with increasing sediment organic matter up to a concentration of about 20 percent dry sediment mass. Poor growth was obtained also on inorganic sediments with a sand fraction exceeding 75 percent dry sediment mass. Diminished growth on organic sediments occurred at low values of sediment density, and on sands at high values of sediment density. Differential centrifugation of organic sediment, facilitating an increase in sediment density with no change in organic matter content, stimulated Hydrilla growth, indicating that sediment density rather than organic matter content was most influential in regulating growth. Macrophyte growth and nutrient accumulation in shoots were closely correlated, but essentially unrelated to concentrations of nutrients in shoots. Additions of phosphorus and iron in combination to organic sediments with nitrogen supplied in the overlying solution resulted in significant growth increases in Hydrilla, suggesting that diminished growth on unfavorable sediments was caused by multiple nutrient limitation. It is further postulated that variations in the ability of different aquatic macrophytes to cope with infertility or other factors associated with unfavorable sediment composition may influence the species composition of aquatic macrophyte communities.

Download or read book Aquatic Plant Control Research Program The Rhizosphere Microbiology of Rooted Aquatic Plants written by Douglas Gunnison and published by . This book was released on 1988 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rhizosphere includes the root systems of higher plants and the assemblages of microorganisms associated with them. Plant-microbe interactions in the rhizosphere have not been extensively examined in freshwater plants. However, information based on studies conducted in other environments indicates that these interactions may be important in freshwater systems. This report, based on a review of the literature, examines several aspects of the rhizosphere of rooted aquatic plants. These include: the nature and properties of the rhizosphere; the manner in which plants influence the rhizosphere microflora; the microbial transformations of nutrients in the rhizosphere; and the overall role of the rhizosphereemicroflora in affecting plant growth regulation through influences on nutrient availability, sediment oxidation-reduction status, and gas formation. Sediment is a complex chemical and microbiological environment, even in the absence of plant roots. The presence of anaerobic conditions, accompanied by a low oxidation-reduction potential and often by toxic constituents, places stresses on plants using anaerobic sediments as a rooting medium. Plant roots have developed strategies for coping with life in anaerobic sediments; certain of these strategies directly influence the surrounding sediments and the rhizosphere microflora. Keywords: Aquatic plants; Bacteria; Decomposition; Denitrification; Nitrogen fixation; Phosphorus; Phosphorus solubilization; Plant growth hormone; Plant growth regulator.

Download or read book Managing Lakes and Reservoirs written by North American Lake Management Society and published by University of Wisconsin Press. This book was released on 2001 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written for the lake user, this third edition testifies to the success and the leadership of EPA's Clean Lakes Program.

Download or read book Herbicides in Asian Rice written by Rosamond Naylor and published by Int. Rice Res. Inst.. This book was released on 1996 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: Overview; Impacts of herbicides; Integrated weed management; Use of herbicides in asian rice.