Papers by Jeanette Norton
Journal of the American Society for Horticultural Science, 1985
Table beet (Beta vulgaris L.) 'Ruby Queen' seeds were either germinated in aerated water till rad... more Table beet (Beta vulgaris L.) 'Ruby Queen' seeds were either germinated in aerated water till radicle emergence or osmoconditioned (OC) in-1.2 MPa solutions of polyethylene glycol 6000 or M gS04 for 7 days at 15°C. Seeds were sown in soil in growth chambers, infested with Pythium spp., and damping-off incidence was evaluated after 14 days. Disease incidence was reduced, compared to dry sown seeds, as a result of presowing treatments. High populations of bacteria (106-108 CFU/ml of solution) developed during the aerated soak, which protected seeds from Pythium damping-off. Seed leaching or osmoconditioning did not decrease susceptibility to damping-off in the absence of high seed bacterial populations. The fluid drilling gel was studied as a delivery system for chemical fungicides. Damping-off in dry-sown seed was reduced by incorporating thiram into a hydroxyethyl cellulose (Natrosol 250 HHW) gel. Gel alone had no effect on damping-off. In field studies, only slight improvements in stand were attributed to the incorporation of thiram in presowing treatments. Fungicide dressing of dry seed resulted in a large improvement in emergence. All presowing treatments had greater field emergence than dry-sown seeds in the absence of thiram, which was attributed to bacterial protection from damping-off.
Soil Biology & Biochemistry, Nov 1, 2020
Microbial carbon-use efficiency (CUE) is defined as the portion of carbon (C) incorporated into b... more Microbial carbon-use efficiency (CUE) is defined as the portion of carbon (C) incorporated into biomass relative to the total carbon consumed and plays a pivotal role in regulating microbially-mediated C and nutrient transformations in soil. However, little is understood about how CUE is impacted by edaphic properties, like soil moisture. Soil moisture physically regulates microbial activity through its effects on both water potential and water content. Low water potential can result in high, compensatory intracellular solute concentrations that may inhibit biochemical functions through cytoplasmic desiccation, whereas low soil water content results in thin water films that can limit substrate diffusion, reducing microbial access to dissolved substrates. Because these two aspects of soil moisture may affect microbial respiration differently than C assimilation, they may have different effects on CUE. The purpose of this research was to evaluate the relative importance of water potential and water content in regulating CUE of soil microbial communities. Moist soil incubations of a sandy loam soil were used to determine the impact of both aspects of soil moisture on CUE, and soil slurries were used to determine the impact of water potential alone. Both 13 C-acetate and 15 N-ammonium were added to moist soils and slurries to quantify gross rates of C and N transformations. In moist soils, acetate assimilation and respiration rates and gross N mineralization and immobilization rates increased exponentially with increasing soil moisture (− 3.0 to − 0.03 MPa). In contrast, acetate assimilation and respiration and gross N transformation rates remained constant in soil slurries across a similar water potential gradient, created by modifying solute concentrations. Similarly, values of CUE in moist soils increased exponentially with increasing soil moisture, whereas slurry values of CUE remained constant across the soil water potential gradient. Because no changes in rates and CUE were observed in slurries, changes observed in moist soils were attributed to limited substrate diffusion associated with low water contents rather than to adverse physiological effects associated with low water potentials. Results of this study demonstrate that limited substrate diffusion is the primary physical mechanism through which soil moisture regulates microbially-mediated C and N transformation rates and CUE in this sandy loam soil.
AGU Fall Meeting Abstracts, Dec 1, 2019
Chemosphere, Mar 1, 2019
h i g h l i g h t s g r a p h i c a l a b s t r a c t Cadmium (Cd) subcellular partitioning is he... more h i g h l i g h t s g r a p h i c a l a b s t r a c t Cadmium (Cd) subcellular partitioning is heterogeneous. Benzo [a]pyrene (BaP) inhibits Cd accumulation. BaP promoted the production of total protein in the cellular debris fraction. Glutathione S-transferase (GST) is the main influencer of Cd accumulation.
Phytopathology, 1986
Page 1. Ecology and Epidemiology Attachment of Enterobacter cloacae to Hyphae of Pythium ultimum:... more Page 1. Ecology and Epidemiology Attachment of Enterobacter cloacae to Hyphae of Pythium ultimum: Possible Role in the Biological Control of Pythium Preemergence Damping-Off Eric B. Nelson, Wei-Liang Chao. Jeanette ...
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Papers by Jeanette Norton