Thesis (M. Ag. Sci) -- University of Adelaide, Dept. of Agriculture, 1967. / Includes bibliography.

Graduation date: 1995

Thesis (M.Sc.). / Written for the Dept. of Natural Resource Sciences. Title from title page of PDF (viewed 2009/6/25). Includes bibliographical references.

Includes bibliography.

With the loss of field burning the amount of crop residue that remains in perennial ryegrass fields has increased. As the amount of crop residue remaining in the field increases so does annual bluegrass. This has resulted in the increased use of herbicides to control annual bluegrass. However, this increased use has also resulted in herbicide-resistant annual bluegrass. Field experiments were initiated in 1997 to investigate residue management options available to growers and their impacts on annual bluegrass emergence. Two sites, Glaser and Wirth, were established with three residue management treatments replicated four times. The treatments included full-straw, bale/flail, and vacuum sweep. Perennial ryegrass seed yield and annual bluegrass seed contamination were evaluated. The vacuum sweep treatment had lower annual bluegrass emergence than the full-straw or the bale/flail treatments during the 1997-98 growing season, for both sites. The fall of 1998 was much drier than the fall of 1997. Annual bluegrass emergence in all plots was lower in 1998 than in 1997 because of the dry conditions. Fall emergence in 1998 was higher in the vacuum sweep treatment than in the other two treatments, which may have been the result of better soil-seed contact in the vacuum sweep treatment. Lower emergence in the spring at the Wirth site compared to the Glaser site may have been due to narrow crop row spacing and cultivar selection, which shaded the annual bluegrass. When growing seasons were combined, there were no treatment differences. However, more emergence was observed in the spring at the Glaser site compared to the Wirth site. Yield was highest for the vacuum sweep treatment at the Glaser site in the 1998-99 growing season. However, competition from volunteer perennial ryegrass in the full-straw and bale/flail treatments could have accounted for this increase. No other differences in yield and no difference in contamination among treatments were observed. However, contamination at the Glaser site was higher in the 1998-99 growing season than in the 1997-98 growing season. Experiments were conducted in growth chambers to determine how differing environmental conditions affect seed germination of diuron-susceptible and diuron-resistant annual bluegrass. Cumulative germination for the susceptible-biotype decreased from 96% to 88% while the resistant-biotype remained above 95% as temperature decreased from 3 0/20 C to 10/2 C. The susceptible-biotype germinated sooner than the resistant-biotype regardless of temperature. The susceptible-biotype had a higher rate of germination than the resistant-biotype at 30/20 C, but not when the temperature decreased to 10/2 C. Germination response to differing matric potentials did not vary much within a biotype for a given soil type and temperature. Therefore, parameters estimated at -1.03 MPa were chosen to contrast susceptible- and resistant biotypes, and soil types, for each temperature. Maximum cumulative germination was greater than 96% for all treatments. When germination on a given soil type was contrasted, differences were only seen for the susceptible biotype vs. resistant biotype on Dayton soil; and the resistant biotype on Dayton soil vs. resistant biotype on Woodburn soil at both temperatures. The lag in onset of germination was shorter for the susceptible biotype on Dayton soil and resistant biotype on Woodburn soil than the resistant biotype on Dayton soil at 30/20 C. At 18/5 C, the lag in onset of germination was shorter for the susceptible biotype on Dayton soil and resistant biotype on Woodburn soil than the resistant biotype on Dayton soil (P = 0.000 1 and 0.0001, respectively). But the rate of germination was faster for the resistant biotype on Dayton soil than both the susceptible biotype on Dayton soil and resistant biotype on Woodburn soil at 18/5 C (P = 0.02 and 0.0004, respectively). The rate of germination did not differ at 3 0/20 C. When just the soils were contrasted, at 18/5 C all annual bluegrass seeds on the Woodburn soil germinated sooner and the rate of germination was higher than on the Dayton soil. These results indicate that the hydraulic properties of the soils may influence germination. However, this was not observed at 30/20 C. The results suggest that the susceptible-biotype was more sensitive to temperature while the resistant-biotype was more sensitive to moisture. Changing crop management in ways that will reduce annual bluegrass emergence and establishment is needed. By altering management strategies, growers may obtain more efficient and effective use of herbicides, while reducing the selection of herbicide-resistant annual bluegrass. / Graduation date: 2000

Legislation to reduce open field burning in grass seed fields within the Willamette valley of western Oregon changed established production practices. In the creeping grasses such as Kentucky bluegrass (Poa pratensis L.) and creeping red fescue (Festuca rubra L.) non-thermal management resulted in reduced yield. Studies were conducted to examine the effects of three stubble height treatments in comparison to open field burning in creeping red fescue seed production. The effects of light quality on characteristics of plant development were investigated in field and controlled environments. Exogenous applications of plant growth regulators (PGR's) were made to elucidate the causes of low seed yields observed without burning. Field plots were prepared in fall of 1994, and 1995 in creeping red fescue commercial production fields as well as at Hyslop research farm in 1995. Three cultivars were included in the trial; Shademaster and Hector, which produce many rhizomes, and Seabreeze which produces few rhizomes. The effects of stubble height, PGRs, and field burning were measured during fall regrowth and flowering. Non-structural carbohydrates available for early regrowth were reduced when stubble was removed below 5.0 cm, particularly in first-year stands. Fall tiller height was increased by stubble remaining and was negatively correlated with flowering. Rhizome development was reduced when stubble was removed mechanically or burned to the crown, whereas yield potential was increased. Fall ethylene application reduced fall tiller height, fall tiller number, and percent fertile tillers the following spring and was similar to control treatment compared with burn. Other PGRs did not produce consistent results in this study. Excess ethylene produced by decaying stubble may impact floral induction and reduce yield potential in creeping red fescue seed crops. Light quality as measured by red:far-red ratio (R:FR) was reduced by canopy closure during regrowth but not by the presence of stubble. In controlled environment studies, red light (R) promoted taller tillers, greater stage of development, and greater tiller number than far-red (FR) light. Sunlight enriched with FR completely inhibited rhizome formation. Results suggest that environments with excess reflected FR may negatively impact early development of creeping red fescue seed crops. / Graduation date: 1998

Thesis (M.Ag.Sc.) -- Dept. of Soil and Water, Waite Agricultural Research Institute, University of Adelaide, 2002? / Bibliography: leaves 105-129.

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 128-134).

Thesis (Ph.D.) - University of KwaZulu-Natal, Pietermaritzburg, 2010. / Full text also available online. Scroll down for electronic link.

Thesis (Ph. D.)--University of Idaho, 2005. / Abstract. "December 2005." Includes bibliographical references (leaves 88-92). Also available online in PDF format.