Doctor of Philosophy / Department of Horticulture and Natural Resources / Jack Fry / Megan Kennelly / Zoysiagrasses (Zoysia spp.) use C4 metabolism and are more drought resistant than C3 grasses. However, the long dormancy period between autumn and spring limits the use of zoysiagrass by homeowners and professional turfgrass managers. In addition, large patch has become the primary pest on zoysiagrass, and improved cultivars with good cold hardiness and large patch resistance are needed in the transition zone. Tall fescue (Schedonorus arundinaceus Schreb), a C3 grass, is used frequently in Kansas due to its heat and drought tolerance compared to some other C3 grasses. However, brown patch (Rhizoctonia solani) is the main disease limiting its growth in summer. Alternatively, mixing zoysiagrass with tall fescue may help reduce brown patch incidence. The objective of these projects were to: (1) evaluate methods for establishing a perennial mixture of seeded zoysiagrass and tall fescue; (2) determine whether a zoysiagrass/ tall fescue polystand is less susceptible to brown patch and results in improved summer quality compared to a tall fescue monostand; and (3) evaluate experimental zoysiagrass genotypes to identify one or more potential new cultivars which have high quality and tolerance to cold and large patch. I found that polystands of zoysiagrass and tall fescue were most successfully established by seeding zoysiagrass at 49 kg ha-1 in June and tall fescue at 392 kg ha-1 in September into the established zoysiagrass sward. Polystand establishment was also superior at a 1.9 cm mowing height than a 5.1 cm mowing height. The resulting mixture resulted in improved turf color in late fall and early spring compared to a zoysiagrass monostand. In addition, using a zoysiagrass-tall fescue polystand reduced brown patch by up to 21% compared to a tall fescue monostand. In the zoysiagrass breeding project, I identified ten progeny out of sixty evaluated that had better tolerance to large patch (up to 40 % less plot area affected) and better quality compared to Meyer zoysiagrass, which is the standard cultivar used in the transition zone.

Measures of temperament have been shown to influence physiological responses. Exit velocity (EV) has been identified as an objective, robust measure of temperament that can be used to predict subsequent performance of cattle. Additionally, previous studies from our lab indicate this measure of temperament may be related to production of interferon-γ (IFN-γ), a cytokine associated with cell-mediated immunity (CMI). Whereas research has investigated effects of EV upon immune responses, the overall goal of these studies was to examine this relationship under a variety of scenarios including human handling, transportation, and exposure to endophyte-infected tall fescue (E+) for determination of its ability to influence CMI in cattle. In each of 5 experiments, calves were classified as either high or low EV animals, based upon measurements obtained prior to initiation of experimental periods. The hypothesis for these studies was that calves with high exit velocities would have lower systemic immune responses to applied treatments. Two experiments were designed to examine the relationship between exit velocity and lymphocyte IFN-γ production during and following a period of exposure to E+ seed and increased temperature humidity index conditions. Preliminary measures of this cytokine indicated a positive relationship with EV. During application of heat and E+ treatment application, no differences in IFN-γ production were detected between EV or endophyte treatment groups. However, in both experiments, after temperatures were returned to thermoneutral and E+ heifers were placed on the endophyte-free treatment, the positive relationship between exit velocity and total lymphocyte production of IFN-γ observed in baseline samples was reestablished. Similarly, during an experiment examining IFN-γ production by lymphocytes in steers during the 4 weeks following a 10h, 805 km transport study, average lymphocyte production of IFN-γ was higher and lymphocyte proportions producing IFN-γ lower in low EV steers, but total lymphocyte production of this cytokine did not differ between exit velocity treatments. In a grazing and finishing study, cattle were placed on E+ or novel endophyte pastures, with balanced representation of low and high EV treatments within each pasture. During the subsequent finishing period, blood samples for lymphocyte IFN-γ production were collected from a single high EV calf from each pasture group. Neither endophyte nor exit velocity was detected to be related with lymphocyte production of IFN-γ. In an experiment examining changes in cytokine gene expression changes during acclimation to human handling, IFN-γ, Il-6, IL-10, and IL-12 were observed to increase linearly over the experimental period in all calves, irrespective of exit velocity designation. In the same experiment, whole period pro-inflammatory tumor necrosis factor-α expression was higher for high EV calves, but interferon-γ (IFN-γ) was lower in this same treatment group. These studies, cumulatively, indicate EV may be related to systemic production of IFN-γ, but abrupt changes to an animal’s environment may serve to mask this relationship.

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

Consumption of toxic endophyte-infected (E+) tall fescue pastures is known to have a negative impact on bull reproductive performance. Since decreased cleavage rates of embryos fertilized with spermatozoa from bulls grazing E+ tall fescue pastures have been observed in several studies using differing sets of bulls, technicians, pastures, and other methods of inducing tall fescue toxicosis (ergotamine tartrate), it is hypothesized that spermatozoa function from bulls grazing E+ is impaired in ways undetectable by gross semen examination. During a three-month grazing study, 6 Angus bulls were utilized to determine the effects of grazing E+ tall fescue pastures on growth performance and spermatozoa function. Bulls were appointed to graze Kentucky 31 tall fescue (Festuca arundinacea Schreb.) infected with Neotyphodium coenophialum, an ergot alkaloid producing endophyte (n=3) or Jesup tall fescue infected with non-ergot alkaloid producing endophyte (NTE) MaxQTM (n=3). Bulls were grouped by body weight (BW) and scrotal circumference (SC) to graze pastures from April 18-June 26, 2007. Blood samples, BW, SC, semen, and rectal temperatures (RT) were collected every 7 d. Scrotal temperatures (ST) were obtained before semen collection each week in June. Semen was evaluated for gross motility, morphology, and Computer Assisted Semen Analysis (CASA) parameters. Semen from a subset of bulls (n=2 per treatment) was used to assess spermatozoa ability to function utilizing in vitro assays. Growth performance was decreased in E+ bulls compared to bulls grazing NTE tall fescue pastures (P = 0.002). Concentrations of prolactin were reduced in bulls grazing E+ compared to bulls grazing NTE tall fescue pastures (P = 0.055). Motility post-thaw and during a 3-hour stress test were decreased (P = 0.024 and P < 0.0001, respectively), in addition to altered CASA parameters for spermatozoa. Penetration was reduced in oocytes fertilized with spermatozoa from bulls grazing E+ (64.54 ± 3.28%) compared to NTE tall fescue pastures (87.42 ± 1.63%, P < 0.0001) coupled with hastened meiotic completion, and reduced intracellular calcium parameters. These findings indicate impaired spermatozoa function in bulls grazing E+ tall fescue pastures that extends beyond gross semen characteristics, and may provide direction for future studies.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 52-64). Also available on the World Wide Web.

A study investigating the effect of sheep stocking density and grazing duration on forage intake, grazing efficiency, dietary selectivity and subsequent forage accumulation in tall fescue(Festuca arundinacea)- subclover(Trifolium subtaranium) pastures was conducted near Corvallis, Oregon during early and late spring in 1988 and 1989. Grazing treatments were 2, 6, and 10-day duration and corresponding stocking densities 380, 130, 78 and 1390, 460 and 280 ewes/ha during early and late trials each year, respectively. Average daily intake and grazing efficiency were highest (P< 0.05) in the 10-day duration and lowest in the 2-day duration. During the first 2 days of all duration treatments, average daily intake decreased as stocking density increased (P< 0.05). Manure cover and crowding stress may explain lower average daily intake under the shorter duration/high density treatments. However, stocking density had little effect on grazing efficiency. This was largely due to the high amount of forage destroyed under the low density treatments which offset the effect of higher forage intake of that treatment. Within the 10-day duration treatment, average daily intake was the same over time (P> 0.05), while grazing efficiency decreased as grazing progressed (P< 0.05). The low grazing efficiency during the early stages of grazing reflected high initial forage destruction probably caused by the movement of animals at the start of grazing to establish bedding and habitual use areas. Growth rate of forage after grazing was highest in the longer duration paddocks and lowest in the shorter duration paddocks (P< 0.05), but the yield was similar under all treatments (P> 0.05). Although short duration/high density grazing is considered to be non-selective, sheep were equally or more selective under very short duration/very high density compared to longer duration/lower density treatments in this study. The 2 days duration was not an attractive management option since the intake and grazing efficiency were low, and the animals were selective. / Graduation date: 1993

Exotic plant invasions represent a significant threat to the integrity of native grasslands. Across the Northern Great Plains, grasslands invaded by smooth brome (Bromus inermis Leyss) support lower plant diversity, potentially resulting in important consequences for ecosystem function. Previous research on smooth brome has primarily focused on aboveground changes in plant communities, but there is growing evidence that the soil ecosystem can be significantly altered with invasion. The two objectives of this thesis were to examine whether smooth brome invasion alters soil nitrogen cycling, and to determine if changes in plant community diversity or productivity influence soil bacterial communities. Relationships between smooth brome and the soil ecosystem were assessed using data collected from a Festuca hallii Vasey (Piper) (plains rough fescue) grassland located near Macrorie, SK. Gross rates of nitrogen cycling and community productivity from smooth brome invaded and native grassland sites were compared to determine the potential influence of smooth brome invasion on the soil nitrogen cycle. The relationship between increasing smooth brome abundance and soil bacterial structure and composition was also studied. Gross mineralization rates and total soil nitrogen were significantly higher in smooth brome-invaded areas relative to native grassland. Bacterial and archaeal amoA, used as indicators of ammonia-oxidizer population sizes, were altered by smooth brome cover. Higher gross mineralization rates were likely due to stimulated microbial activity caused by increased litter and root production in areas invaded by smooth brome. Smooth brome decreased plant species richness through increased litter production, but had the opposite effect on bacterial communities. Bacterial communities had higher species richness and evenness in soils invaded by smooth brome, and smooth brome invasion was also associated with bacteria important for soil nitrogen cycling. As bacteria dominate microbial biomass and are important for decomposition processes, a more even bacterial community may have supported increased mineralization rates in smooth brome-invaded soils. Specifically, a more even bacterial community may have increased mineralization rates through greater resource utilization and niche partitioning. The responses observed in these studies suggest that belowground changes with smooth brome invasion have the potential to have important consequences for ecosystem processes.

Tall fescue is the most common cool-season grass in the eastern USA, with broad economic and ecological importance to the region. Tall fescue is known to associate with a fungal endophyte, Neotyphodium coenophialum, whose presence can decrease biotic and abiotic stress experienced by the plant. This thesis evaluates the response of tall fescue and the fungal endophyte symbiosis to predicted climate change. I participated in two multi-factor climate change projects where I investigated the response of tall fescue tissue chemistry and growth to various climate change factors. Endophyte-infected (E+) tall fescue had decreased alkaloid production under elevated CO2 but increased alkaloid production under elevated temperatures. Significant differences between E+ and E- (endophyte-free) tall fescue tissue chemistry were also found, suggesting the endophyte interacts with the plant response to abiotic stress. Although several studies have reported benefits of endophyte infection for tall fescue growing under drought stress, my research found no differences between E+ and E- total growth and surprisingly showed increased mortality of E+ individuals under elevated temperature. Taken together, my research indicates that this grass-fungal relationship will respond to climate change, and may produce dramatic and unforeseen results that question the widely believed mutualistic nature of the symbiosis.

Sixty steers were grazed on toxic tall fescue for 104 days to determine the effects of hair coats and steroidal ear implants on physiological measurements. Steers were stratified by body weight and hair coat color for assignment to six, 3.0-ha pastures of 'Kentucky 31' tall fescue. Main plot treatments of either ten clipped or ten unclipped steers were randomly assigned to pastures. Five steers in each pasture were implanted with Synovex-S (200 mg progesterone-20 mg estradiol) and five were implanted with Compudose (25 mg estradiol) as sub-plot treatments. Hair growth rate averaged 0.29 mm/day. Sweating rate declined (P andlt; 0.001) over the grazing period and was higher (Pandlt; 0.10) with the estradiol implant. Rectal temperatures were lower (P andlt; 0.05) in clipped cattle (39.3 vs. 39.5??C) when the highest ambient temperature (33??C) of the study was recorded. At high environmental temperatures, percentage of steers actively grazing was negatively correlated (P andlt; 0.10) with ambient temperature. Winter hair coat retention, continuous hair growth, and reduced sweating caused impaired thermoregulation and thus decreased grazing frequency resulting in poor animal performance.

Ten wether lambs were used to determine the effects of ergovaline consumption from endophyte infected tall fescue, on nutrient utilization and metabolism. Lambs were fed a diet of 23% endophyte free tall fescue seed (E-) and 77% concentrate from d -14 to -1 (adaptation phase). On d 0, five lambs were switched to an endophyte infected seed diet (E+) where they remained through d 14. Nutrient digestibilities tended to increase from adaptation through the acute (d 1 to 4) to subacute (d 10 to 14) phases when E- was fed. E+ digestibilities were highest (P < 0.05) in the acute phase. Lambs fed E+ had higher rectal temperatures in the acute (P < 0.01) and subacute phases (P < 0.05). Fecal recovery of ergovaline increased as day of collection increased in the acute and subacute phases. Lysergic acid fecal recovery increased with day of collection in the acute phase, but no effect was found in the subacute phase. Serum enzyme analyses did not indicate tissue damage from alkaloid consumption. These results demonstrate lambs try to adapt to endophyte infected fescue seed consumption through increased nutrient digestibilities and increased ergovaline and lysergic acid excretion.