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Full-Text Articles in Life Sciences
Analysis Of The Effects Of Hypogeal And Epigeal Emergence On Seedling Competition In Legumes, Keith E. King
Analysis Of The Effects Of Hypogeal And Epigeal Emergence On Seedling Competition In Legumes, Keith E. King
McCabe Thesis Collection
Seedling emergence is either hypogeal or epigeal. In hypogeal emergence the cotyledons remain below the soil surface during seedling development, while in epigeal emergence the cotyledons extend above the soil surface due to elongation of the hypocotyl. Here we examine the effect of seed size, and emergence type, on seedling growth. Six legumes with variation in seed size and either epigeal or hypogeal emergence were grown under dark and light conditions. A competition study was also conducted where a hypogeal and epigeal legume were grown in combination with wheat and ryegrass. Legumes expressing epigeal emergence were cowpea (Vigna unguiculata), mung …
Field Testing Of Abrasion Resistant Carbides, Kevin C. Orme
Field Testing Of Abrasion Resistant Carbides, Kevin C. Orme
Undergraduate Honors Capstone Projects
Chromium, tungsten, titanium, and vanadium carbides were investigated to determine relative cost of operation for each in an agricultural environment. For use on a ripper plow, these carbides were field tested in two different soil types; one soil having a matrix of gravel and cobblestones, and the other consisting of hard dirt and large underground rocks. Each alloy was applied to a high carbon plow point using an arc welding process. Along with the welded points, cast chromium carbide was tested. The results are given in price per acre and not solely longevity of the point. It was concluded that …
Availability Of Humic Nitrogen To Phytoplankton, Jason Holt See
Availability Of Humic Nitrogen To Phytoplankton, Jason Holt See
Dissertations, Theses, and Masters Projects
The chemical, physical, and biological factors affecting the bioavailability of humic nitrogen (N) to coastal phytoplankton were examined. Historically, humic substances have largely been considered biologically refractory, and humic-N is though to be unavailable biologically without prior oxidation via photochemical cleavage or remineralization by bacteria. This is due in part to the high aromaticity and low N content of humic substances. This dissertation investigates whether these assumptions are valid, and whether humic substances may be a more important source of N to the coastal phytoplankton community than previously believed. The research consisted of four main parts. First, changes in the …
Microbial Dynamics And Biogeochemistry In The North Pacific Subtropical Gyre, Matthew J. Church
Microbial Dynamics And Biogeochemistry In The North Pacific Subtropical Gyre, Matthew J. Church
Dissertations, Theses, and Masters Projects
The research presented in this dissertation describes the influence of planktonic bacterial growth on upper ocean organic matter dynamics in the North Pacific Subtropical Gyre (NPSG). Examination of the temporal dynamics in dissolved organic matter (DOM) was coupled with investigations that targeted the influence of heterotrophic bacterial production (HBP) on organic matter fluxes in the NPSG. Nine cruises to the Hawaii Ocean Time-series field site Station ALOHA revealed that HBP accounted for a large flux of organic carbon in the upper ocean of the NPSG. HBP was significantly enhanced by sunlight, with photoenhancement of HBP accounting for 3.2 mol C …
12,000-Year Record Of Lake-Level And Vegetative Change At Mathews Pond, Piscataquis County, Maine, Usa, Andrea Masterman Nurse
12,000-Year Record Of Lake-Level And Vegetative Change At Mathews Pond, Piscataquis County, Maine, Usa, Andrea Masterman Nurse
Electronic Theses and Dissertations
This study of late-glacial and Holocene changes in lake-level and vegetation at Mathews Pond contributes new information about Holocene environments in northeastern North America. The research establishes a 12,000-year record of paleohydrology for the watershed adjacent to Big Reed Forest Reserve, the largest stand of old-growth forest in the northeastern United States. Mathews Pond is a 7.4 ha, closed-basin, groundwaterseepage lake located in an upland, forested region of the Aroostook River drainage system. Glacial meltwater briefly filled the basin - 13.0 ka (1 ka = 1000 I4C yr BP)). The lake existed as a shallow pool in the deep area …
Sedimentological And Plant Taphonomic Evaluation Of The Early Middle Devonian Trout Valley Formation, Jonathan Allen
Sedimentological And Plant Taphonomic Evaluation Of The Early Middle Devonian Trout Valley Formation, Jonathan Allen
Honors Theses
The Trout Valley Formation of Emsian-Eifelian age, outcropped in Baxter State Park, Maine, consists offluvial and coastal deposits preserving early land plants. Massive, crudely bedded conglomerate represents deposits of proximal braided channels on an alluvial fan complex. Lithic sandstone bodies in channel-form geometries represent deposits of river channels draining the Acadian highlands whereas associated siltstones represent overbank deposits, intertidal flats, and tidal channels. Localized lenticular quartz arenites represent nearshore shelf bar deposits that were storm influenced. The majority of plant assemblages preserved mainly in siltstone lithologies are allochthonous and parautochthonous, with only one autochthonous assemblage identified in the sequence. Plant …