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  • Benthic algal flora of four rivers of the middle Willamette River Basin

    Creator:
    Todd, Leona Esther
    Abstract:
    Fresh-water benthic river algae were collected from selected sites in Willamette River tributaries; two sampling sites were in the Yamhill River system and four sampling sites were in the Santiam River system. Twelve samples were taken at each collection site in the Yamhill River system at approximately monthly intervals from...
    Resource Type:
    Dissertation
    Full Text:
    samples. The smallest number of genera were found in the March collections. A total of 14,986 individual

  • Structure and productivity of marine benthic diatom communities in a laboratory model ecosystem

    Creator:
    Wulff, Barry Lee
    Abstract:
    Effects of light intensity, exposure to desiccation, reduced salinity, and thermal elevation on the functional and structural characteristics of marine benthic diatom communities were investigated in a laboratory model ecosystem and a respirometer chamber. Measurements of biomass (dry weight and ash-free dry weight) and chlorophyll a were made for each...
    Resource Type:
    Dissertation
    Full Text:
    was caused by an increase in the number of species, but in the winter experiment this was caused by

  • Ascocarp development in Anthracobia melaloma

    Creator:
    Larsen, Harold J.
    Abstract:
    Cultural and developmental characteristics of a collection of Anthracobia melaloma with a brown hymenium and a barred exterior appearance were examined. It grows well in culture on CM and CMMY agar media and has a growth rate of 17 mm in 18 hours. It is heterothallic and produces asexual multinucleate...
    Resource Type:
    Masters Thesis
    Full Text:
    number of four is confirmed for the species. Exposure to fluorescent light was unnecessary for

  • Biosystematics of the Mimulus nanus complex in Oregon

    Creator:
    Ezell, Wayland Lee, 1937-
    Abstract:
    A biosystematic study was made in seven populations of Mimulus nanus Hook. & Arn. and M. cusickii (Greene) Piper (Scrophulariaceae) in central Oregon, and a taxonomic revision was made of the four species of section Eunanus reported from Oregon--M. nanus, M. cusickii, M. clivicola Greenm. and M. jepsonii Grant. Mimulus...
    Resource Type:
    Dissertation
    Full Text:
    Pore Number 20 Ovule and Seed Counts 20 Hybridizations 21 Seed Germination 22 Statistical Analysis 24

  • Effects of cork bark disease on cambial activity and secondary tissues in Abies lasiocarpa (Hook.) Nutt

    Creator:
    Carr, John Edward, 1943-
    Abstract:
    Abies lasiocarpa (Hook.) Nutt. (sub-alpine fir) trees of comparable vigor growing in eastern British Columbia were studied in order to determine the effects of cork bark disease on phellogen and vascular cambium activity. Diseased trees form hard deeply fissured rhytidome several inches thick over large areas of the bole when...
    Resource Type:
    Dissertation
    Full Text:
    . 60 20 Cross section of 1968 xylem increment in control tree number 1. 61 21 Cross section of 1968

  • Ethylene production from cultures of Cylindrocladium and from Cylindrocladium-infected azalea leaves

    Creator:
    Axelrood, Paige Ellen
    Abstract:
    Ethylene was produced by Cylindrocladium floridanum and C. scoparium in culture. Production was methionine dependent and maximal during the active growth phase of the fungus, beginning shortly after spore germination. More ethylene was produced sooner by C. floridanum than C. scoparium. Ethylene was produced by Cylindrocladium both from active mycelium...
    Resource Type:
    Masters Thesis
    Full Text:
    azalea leaves was first detectable 17-21 hours after inoculation and increased sharply with the onset

  • Ultrastructure of dormant and germinating conidia of Aspergillus nidulans

    Creator:
    Florance, E. R.
    Abstract:
    The cell wall of dry, dormant conidia of Aspergillus nidulans is three-layered. The wall of hydrated conidia is five-layered and the germ tube wall is continuous with the innermost layer. The outermost layer consists of rodlets measuring 10 nm in diameter. Mitochondria and endoplasmic reticulum increase in number and amount,...
    Resource Type:
    Masters Thesis
    Full Text:
    in number and amount, respectively, during hydration and germination and vacuoles increase in size

  • Effects of the balsam woolly aphid (Adelges piceae (Ratzburg)) on the cambial activity of grand fir (Abies grandis (Dougl.) Lindl.) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.)

    Creator:
    Sisson, Warren Elmer, Jr.
    Abstract:
    Cambial activity was studied in trees infested by the balsam woolly aphid and in non-infested trees of grand and subalpine fir. Infested and non-infested samples of grand fir were collected near Corvallis during 1968 and 1969. Samples of subalpine fir, noninfested and infested, were collected near Odell Lake, at approximately...
    Resource Type:
    Dissertation
    Full Text:
    species between infested and non-infested trees were noted in the number of overwintering immature (preco

  • Relationships of six saprozoic nematodes and a nitrogen-fixing bacterium, Rhizobium japonicum (Kirch.) Buchanan

    Creator:
    Sontirat, Suebsak
    Abstract:
    Relationships of six species of saprozoic nematodes, Pristionchus lheriteiri (Maupas, 1919) Paramonov; Panagrolaimus subelongatus (Cobb, 1914) Thorne, 1937; Cephalobus persegnis Bastian 1865; Pelodera (Rhabditis) lambdiensis (Maupas, 1919) Dougherty, 1953; Rhabditis sp. I and Pelodera chitwoodi (Bassen, 1940) Dougherty, 1955 and a nitrogen-fixing bacterium, Rhizobium japonicum (Kirchner, 1895) Buchanan, 1926 were...
    Resource Type:
    Dissertation
    Full Text:
    bacteria after 21 hours in every replication are less than the average number of bacterial cells ingested

  • Factors affecting a bioassay for Agrobacterium tumefaciens in natural soil

    Creator:
    Jaeger, Joy Rae
    Abstract:
    Tomato seedlings were used to assay the population of A. tumefaciens in artificially contaminated soil. Aqueous soil suspensions were applied directly to the wounded stem. The bioassay was used because not all pathologically important physiological strains of A. tumefaciens would grow on any of the selective media available. This method...
    Resource Type:
    Masters Thesis
    Full Text:
    number which had been identified. Recent work in Australia (20, 21), and our work in Oregon, indicates