Life Sciences Commons^™

The Response Of Five Tropical Plant Species To Natural Solar Ultraviolet-B Radiation, Peter S. Searles

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Tropical regions currently receive the highest global levels of solar ultraviolet-B radiation (UV-B, 280-320 nm) even without ozone depletion. Thus, the influence of natural, present-day UV-B irradiance in the tropics was examined for five tropical species, including three native rainforest tree species and two economically important species. Solar UV-B radiation conditions were obtained vi using either a UV-B excluding plastic film or a near-ambient UV-B transmitting film in a small clearing on Barro Colorado Island (BCI), Panama (9 ° N). Significant differences were often exhibited as increased foliar UV-B absorbing compounds, increased leaf mass per area, and reduced leaf blade …

Dungpat Microenvironmental Effects On Germination And Establishment Of Crested Wheatgrass, Ghulam Akbar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Complementary greenhouse and field studies investigated the effects of ambient environmental conditions on cattle dungpat moisture, temperature, nutrient concentration, and crust formation dynamics, which in turn influence seed germination and seedling establishment in dungpats. 'Hycrest' crested wheatgrass [Agropyron desertorum (Fisch. ex Link) X A. cristatum (L.) Gaert.] was used as a representative revegetation species.

After collecting feces from Holstein steers that had been fed crested wheatgrass seeds, uniform dungpats were prepared and placed on two soil types (loam and coarse sand) in containers under three watering treatments (field capacity, 1/2 field capacity, and no water) in the greenhouse. Dungpat …

Influences Of Nitrogen Supply And Elevated Co2 On Nitrogen Consumption, Nitrogen Loss, Tissue Nitrogen Concentration, And Yield Of Hydroponic Wheat, Karl B. Ritchie

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Wheat was grown hydroponically for 23 days (early boot stage) in a controlled environment at NO₃^- concentrations of 100 and 1000 μmol and CO₂ levels of 360 and 1200 μmol mo1^-1. Nitrogen consumption and transpiration were measured daily. Tissue nitrogen concentration, total biomass, and percent root mass were measured at harvest. Nitrogen recovery and nitrogen use efficiency were calculated. Elevated CO₂ increased nitrogen consumption of the 100 μmol NO₃^- treatment by 13.6% and the 1000 μmol NO₃^- treatment by 21.3%. These increases were particularly evident during …