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Item Salinity Tolerance of Tall Fescue (Festuca arundinacea Schreb.)(North Dakota State University, 2011) Gao, YangTall fescue (Festuca arundinacea Schreb.) is one of the commonly used cool-season turfgrass species. Despite the many advantages of tall fescue, there are some properties that restrict its use as turf grass. Recent efforts on selection of turf-type tall fescue focus on fine leaf texture, darker green color, seedling turgor, overall density, tolerance to extreme temperatures, and other stresses. The objectives of this research were to develop techniques in screening salinity tolerant tall fescue and to investigate the leaf senescence process, growth and nutrient uptake of tall fescue under salinity stress induced by different types of salt. Two tall fescue cultivars, Tar Heel II (salt tolerant) and Wolfpack (salt sensitive) were grown in silica sand as growth medium and fertilized with Hoagland solution. Salt treatments were added to the medium along with Hoagland solution. At least three indices calculated based on single leaf spectrum showed promise as sensitive means to differentiate salinity stress from untreated plants. Those indices also are strongly correlated to many physiological parameters that have been shown to be reliable measures of salinity tolerance in many plant species including tall fescue. Tall fescue leaf senescence was accelerated by salinity stress which was different from the aging process under shade. Tall fescuc had several adaptation strategies in order to conserve water under salinity stress, while the plants under shade had adaptation mechanisms centered on light harvesting. Tall fescue accelerated old leaf senescence, whereas under shade conditions, tall fescue showed slowing down in the new leaf development as well as mature leaf aging. Tall fescue growth responded to salinity stress differently from shade stress, a fact that has to be taken into consideration when selecting for stress tolerant traits, such as leaf length, root to shoot ratio. Leaf appearance rate may be different with stress tolerance levels and mediate the tiller number and shoot density. By comparing and contrasting the effects on nutrients uptake, it was shown that K, Ca, Mg may be very important in the ion balance and salinity stress tolerance. Tall fescue leaf firing was mainly caused by an alkaline condition with pH higher than 9 as in Na2C03, or moderate pH combined with high salinity (high EC) as in CaC}i. Plant growth was more affected by sodicity which was high in Na2C03 and Na2S04• Osmotic adjustment also played an important role in tall fescue salinity stress in chlorides. Chloride effects were closely related to RWC of the leaves. The combination of different salts along with the variation of their physical and chemical properties, such as EC, pH, and osmotic potential, made the differentiation of their influence on tall fescue stress rather difficult. Multiple properties, such as growth, morphological, and physiological, should be measured to better understand the effects of different salts.Item Phytoremediation of Soils Contaminated by Oil and Gas Drilling and Production Operations Using Grass Species(North Dakota State University, 2014) Gao, YangSoil contaminated by crude oil or drill cuttings poses a threat to ecosystem. The objective of this study was to test tolerance levels of grass species to drill cuttings and crude oil in seed germination and at the 5-leaf stage. Sixty five grass species were screened for their tolerance to crude oil and drill cuttings at the germination stage. Two species were grouped as tolerant, 18 species as moderately tolerant, 27 species as moderately sensitive, and 18 species as sensitive to drill cuttings. In the test with crude oil, 28 species were classified as tolerant, 29 species as moderately tolerant, 6 species as moderately sensitive, and 2 species as sensitive. Nine species were further tested at different contamination levels. Seed germination and seedling biomass of all species was reduced. Buffalograss (Buchloe dactyloides (Nutt.) Engelm.), showed the least reduction of germination and biomass when grown in contaminated soil. Thus, it is a potential species to be used in remediation of oil contaminated with hydrocarbons. Seventy two grass species also were screened at 5-leaf stage for their tolerance to crude oil and drill cuttings. Thirteen species, among which seven are cereal crops, showed visual injury index less than 20 in a 0 to 100 scale, when grown in soil contaminated with drill cuttings. Of the grass species screened, grassy weeds ranked in the top one-third of biomass reduction with only yellow foxtail (Setaria pumila (Poir.) Roem. & Schult.) and foxtail barley (Hordeum jubatum L.) as exceptions. Nine species were chosen to further test the growth and phytotoxicity at different levels of contamination. The responses of those species at mature stages were affected by growing conditions. Nevertheless, barley and yellow foxtail showed lower biomass reduction and phytotoxicity compared with the other species. Using Fourier transform infrared spectroscopy to test the soil samples, it was found that concentrations of hydrocarbons in soil were reduced differently by different species. Annual ryegrass (Lolium multiflorum Lam.) and barley (Hordeum vulgare L.) showed the highest reduction of hydrocarbons from drill cuttings, while yellow foxtail and annual ryegrass showed the highest reduction of hydrocarbons from crude oil contamination.