http://hdl.handle.net/1957/18369 Wed, 19 Jun 2013 11:34:15 GMT 2013-06-19T11:34:15Z http://hdl.handle.net/1957/38588 Seed quality and plant establishment studies of seashore paspalum (Paspalum vaginatum Sw.) Baker, Stanley D. (Stanley David) Seashore paspalum (Paspalum vaginatum Sw.) is an important warm-season perennial turfgrass, known for its tolerance to salinity. Turfgrass is used for homes, municipalities, sod farms, resorts, and sports fields. Seashore paspalum has historically been planted in sub-tropical and tropical climates because of its heat tolerance. Seashore paspalum could become an alternative turfgrass and seed crop in Oregon's Willamette Valley (OWV) if summer temperatures increase because of climate change. Typically, seashore paspalum has been propagated vegetatively through rhizomes and stolons, but transporting this vegetative material has been problematic as much of the material either does not survive or does not transplant well. Ideally, it would be commercially beneficial to grow seashore paspalum from seed. However, planting seed has been restricted due to low seed germination rate, slow germination, and variable establishment in the field. Thus, the purpose of this research was 1) to establish the optimum blowing point (OBP) to separate pure seashore paspalum seeds from light inert matter in order to allow for more accurate seed testing and possibly improved seed cleaning, 2) to determine the extent of dormancy in newly harvested seeds and germination requirements for laboratory germination test, and 3) to identify the optimum time for planting seashore paspalum under OWV environmental conditions. The results for the OBP study showed that an air velocity of 2.2 m/s was the OBP for seashore paspalum. The results of germination studies indicated that there is significant dormancy in seashore paspalum and that given this dormancy, an alternating temperature regime of 20/30⁰C (16 h dark/8 h light) provided best germination test results. The results for the establishment study showed that there were no significant differences in establishment among cultivars of seashore paspalum. Furthermore, seashore paspalum established at a range of 480 to 549 GDD (GDD = [(Max. Temp ⁰ C + Min. Temp ⁰C)/2] - 5⁰ C) based on air temperature and achieved ≥ 90% green within 90 days. July and August proved optimum for establishment due to lower Poa annua intrusion. Graduation date: 2013; Access restricted to the OSU Community at author's request from May 15, 2013 - May 15, 2015 Wed, 01 May 2013 00:00:00 GMT http://hdl.handle.net/1957/38588 2013-05-01T00:00:00Z http://hdl.handle.net/1957/38098 Weed management for giant reed (Arindo donax) biomass production in Oregon Attarian, Amir Giant reed (Arundo donax L.) is a candidate to provide feedstock for the Portland General Electric power plant in Boardman, Oregon. Giant reed is a fast perennial grass, producing 23-27 metric tons ha⁻¹ of biomass and has the ability to adapt to diverse environments making it a good candidate for biomass production. This study tested postemergence and preemergence herbicides for controlling weeds in giant reed during the establishment year in which giant reed plants are more sensitive to weed competition. The greenhouse study demonstrated that among the tested herbicides, bromoxynil plus MCPA at 0.841 kg ai ha⁻¹, nicosulforun at 0.035 kg ha⁻¹, and dimethenamid-p at 0.735 kg ha⁻¹ did not injure giant reed. In a field study, preemergence application of dimethenamid-p at 0.735 kg ha⁻¹ followed by a postemergence application of 2,4-D amine at 0.560 kg ha⁻¹ and a postemergence application of bromoxynil plus MCPA at 0.841 kg ha⁻¹ did not injure giant reed. The presence of weeds in a field does not always mean that crop yield will be reduced and there are some periods during the growing season when weeds will not cause considerable yield loss. Therefore, predicting a critical period of weed control (CPWC) that includes the best time for weed control in giant reed could improve weed management in the field. The length of the CPWC could be different depending on the level of acceptable yield loss (AYL). Our results are reported for AYL of 5 and 10%. The CPWC started at 290 accumulated growing degree days (GDD) and ended at 820 for a 5% AYL, while for a 10% AYL, it started at 333 GDD and ended at 727 GDD. Based on the results, there are some herbicides which could be selected for further study for weed control in the giant reed and the estimated CPWC which could be used to inform weed management practices in giant reed production. Graduation date: 2013 Wed, 06 Mar 2013 00:00:00 GMT http://hdl.handle.net/1957/38098 2013-03-06T00:00:00Z http://hdl.handle.net/1957/38094 Multiple-resistant Italian ryegrass (Lolium perenne spp. multiflorum) populations in Oregon Liu, Mingyang Italian ryegrass (Lolium perenne spp. multiflorum) is a common weed management problem in turfgrasses, cereals and non-crop areas in the United States. In Oregon, the number of populations with multiple-resistance continues to increase. To manage these resistant populations, the resistance patterns must be determined. In this study, five Italian ryegrass populations (CT, R1, R2, R3 and R4) from two cropping systems were studied for resistance patterns and mechanisms. The CT population is from a Christmas tree plantation and was resistant to at least six herbicides with four different mechanisms of action: atrazine, diuron (2.4-fold), glyphosate (7.4-fold), hexazinone (3.1-fold), imazapyr (1.8-fold), and sulfometuron. The resistant indices (RI) for sulfometuron and atrazine could not be calculated because 50% growth reduction for the CT population was not reached even with the highest rates applied, 17.6 kg ai ha⁻¹and 16 kg ai ha⁻¹, respectively, which are 16 times the recommended field application rates for this two herbicides. The CT population accumulated less shikimate than the S population. There were two mutations in the CT population, Trp591 to Leu in the ALS gene and Ser264 to Gly in the psbA gene, which explain the ALS and PII cross resistance, respectively. R1, R2, R3 and R4 were collected from annual cropping systems. All four populations were resistant to flufenacet. RIs for two populations, R2 and R4, were 8.4 and 5.9, respectively. R2 and R4 also were resistant to mesosulfuron-methyl, pinoxaden, quizalofop and clethodim. R4 was resistant to diuron, but R2 was not. An Asp-2078-Gly substitution in the ACCase gene was found in both R2 and R4 populations, while another Ile-2041-Asn substitution in the ACCase gene was found in the R4 population. These mutations explain the ACCase cross resistance in the R2 and R4 populations. The mechanisms for the glyphosate resistance in the CT population and the flufenacet resistance in R1, R2, R3 and R4 populations were not identified in this study. None of the five populations were resistant to the herbicide pyroxasulfone. Graduation date: 2013 Thu, 28 Feb 2013 00:00:00 GMT http://hdl.handle.net/1957/38094 2013-02-28T00:00:00Z http://hdl.handle.net/1957/37720 Influence of planting density on spike size and grain yield in five winter wheat cultivars Wang, Shi Ping, 1956- Graduation date: 1991 Fri, 09 Nov 1990 00:00:00 GMT http://hdl.handle.net/1957/37720 1990-11-09T00:00:00Z