Life Sciences Commons^™

Leaf Epidermal Transmittance Of Ultraviolet Radiation And Its Implication For Plant Sensitivity To Ultraviolet-Radiation Injury, Ronald Robberecht

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Leaf epidermal transmittance of ultraviolet radiation (280-400 nm) was examined in several plant species to determine the capability of the epidermis to attenuate solar ultraviolet radiation. Epidermal samples were mechanically isolated and examined with a spectroradiometer/integrating sphere for transmittance. A survey of 25 species exposed to natural insolation was conducted. Although the species differed in life form, habitat type, and epidermal characteristics, epidermal transmittance was generally less than 10%. Ultraviolet radiation was attenuated 95 to 99% in more than half of the species. In 16 species, flavonoid and related pigments in the epidermis accounted for 20 to 57% of the …

Feeding Behavior Of Pen Reared Mule Deer Under Winter Range Conditions, Michael A. Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study examined the feeding responses of mule deer to a system of spring livestock grazing. The specific purposes were 1) to determine botanical composition of diets selected by mule deer on a winter range subjected to previous spring grazing by sheep compared to one with no sheep grazing and 2) to develop a basis for predicting selection of individual plants by deer, based on physical characteristics of the plants and the species and physical proximity of associated plants.

The study was conducted within the framework of a completely randomized experimental design with two treatments. Variables controlled for each unit …

Photosynthesis, Dark Respiration, And Growth Of Rumex Patientia L. Exposed To Uv-B (280-315 Nm) Irradiance Corresponding To Reduced Atmospheric Ozone Concentrations, William B. Sisson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Net photosynthesis, dark respiration, chlorophyll concentrations and growth were determined for Rumex patientia L. exposed to UV-B radiation corresponding to reduced atmospheric ozone concentrations. The hypothesis of whether reciprocity is maintained in the response of R. patientia to polychromatic UV-B radiation was tested. On the basis of the relationships derived from these studies, a simulation model was developed for the prediction of photosynthesis and growth of R. patientia exposed to UV-B radiation corresponding to any atmospheric ozone reduction.

Photosynthetic rates were found to be depressed after two hours exposure to UV-B irradiance simulating a 0.18 atm·cm ozone column when the …

Seasonal Patterns Of Photosynthesis And Respiration In Atriplex Confertifolia And Ceratoides Lanata, Richard S. White

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Net photosynthesis and dark respiration studies were conducted on Atriplex confertifolia (Torr. and Frem.) S. Wats and Ceratoides lanata (Pursh) J.T. Howell under field and laboratory conditions. These woody species are commonly found in salt desert shrub communities of the Intermountain West. During these investigations, the effects of air temperature, plant moisture stress, soil water potential, irradiation, and plant phenological status were examined with respect to their influence on carbon dioxide (CO₂) exchange.

Intensive field studies were carried out between April and October. This interval corresponded to the major period of physiological activity in both species. The factors …

The Effect Of Urea On The Sedimentation Coefficient Of The Curly Top Virus Dimer, Allen H. Smith

Undergraduate Honors Capstone Projects

The purpose of this project is to investigate the effect of increasing concentrations of urea on the sedimentation rate of the curly top virus dimer as measured by ultracentrifugation techniques. In general, urea causes the breaking of hydrogen bonds in macromolecules--in the case of the virus, increased concentrations of urea should cause changes in the configuration of the virus and may possibly cause a separation of the dimer into monomers. From previous centrifugation studies, we know that the dimer has a characteristic sedimentation coefficient(S) of about 80 Svedbergs; the monomer has an S value of about 55 Svedberg units. Increased …