Nineteen bermudagrass (Cynodon dactylon (L.) Pers.) cultivars were evaluated for field emergence, establishment rate, traffic tolerance, post-harvest seed coating, germination velocity, and total germination under varying temperature regimes. Two cultivars were evaluated for thermal modeling, day/night temperature fluctuations, day lengths, and effects of fluridone on speed and percentage of total germination. The effect of cultivar was highly significant for visible field germination, time to 100% cover, and traffic tolerance in both 2010 and 2011. Riviera was the slowest or equivalent to the slowest for visible germination. Casino Royale was the fastest or equivalent to the fastest for visible germination. Yukon was the slowest to reach 100% cover in both years, while Sovereign was the quickest for 2010. Riviera and Sovereign were equivalent for the quickest to cover in 2011. Riviera and Yukon ranked highest and lowest, respectfully, in tolerance to simulated athletic traffic. There were no significant effects (p>0.05) of post-harvest seed coatings. There were highly significant differences among cultivars in germination velocity and total germination when grown under 20-year average day/night temperatures representing data from Lexington, KY on 15 May to 1 August in 15 day intervals. Evaluations for day/night temperature regimes, day length regimes, and effects of fluridone on the germination speed and percentage were also completed on Riviera and Casino Royale. Day/night regimes of 35/20, 35/25, and 40/25 degrees Celsius were evaluated. Significant differences (p<0.05) were observed, 35/20oC producing the fastest and highest percentage of germination across both cultivars. Day length was evaluated for 8, 12, 14, and 16 hours with no significant differences (p<0.05) observed. Fluridone significantly (p<0.05) decreased the germination time and increased the percentage of total germination of Riviera while only significant differences (p<0.05) in germination time observed with Casino Royale.

Bermudagrass (Cynodon dactylon L.) is often used for athletic fields due to its wear tolerance and recuperative ability. Studies were conducted May 2007 through November 2008 in Lexington, Kentucky. The cultivars ‘Quickstand’, ‘Tifway’, ‘Riviera’, and ‘Yukon’ grown in a sand-based medium were used to investigate differences in wear tolerance and shear strength. Trinexapac-ethyl (TE) was applied at label rates and frequencies or untreated. Overseeding treatments were perennial ryegrass (Lolium perenne L.) at 0, 612, and 1225 kg PLS ha-1. Traffic treatments were applied with a Brinkman traffic simulator 3 d wk-1 August through October. Shear tests were conducted using the Clegg shear tester once wk-1 for the same period. The main effect of cultivar was significant (p Quickstand=Yukon) and overseeding at the medium and high rates. Significant differences (p Tifway =Yukon (2007) and with Riviera ≥ Quickstand > Tifway = Yukon (2008). Significant differences (p0.05) in either year for traffic tolerance or shear strength.

An active football season during the fall acclimation period tests the traffic tolerance of bermudagrass. Exogenous applications of synthetic cytokinins or cytokinin-enhancing plant growth regulators (PGRs), such as trinexapac-ethyl, may improve the traffic tolerance of "Patriot" and "Tifsport" hybrid berudagrasses (Cynodon dactylon var. dactylon x Cynodon transvaalensis). This study was designed to mimic the agronomic practices and traffic stresses experienced at Virginia Tech's Worsham Field. Starting in September 2005, treatments were applied with a differential-slip traffic simulator. Following a traffic treatment, plots received an application of one of three PGRs: 6-Benzyladenine (6-BA), 2-Chloro-4-pyridyl-phenylurea (CPPU) or trinexapac-ethyl (TE). Physiological and morphological responses such as total non-structural carbohydrates and turf density were measured. Previous researchers have shown that increased tissue cytokinins are related to increased tiller density, delay of senescence and enhanced photochemical efficiency. For these reasons, the application of cytokinin enhancing PGRs may have potential to increase bermudagrass traffic tolerance. Patriot's aggressive growth and excellent cold hardiness are predicted to result in better overall traffic tolerance and repair as compared to Tifsport. / Master of Science