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Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 84-89). Also available on the World Wide Web.

The effectiveness of 5-bromo-3-sec-butyl-6-methyluracil (bromacil) for the selective removal of orchardgrass (Dactylis glomerata L.) from Kentucky bluegrass (Poa pratensis L.) turf and some physiological responses of the grasses to bromacil were evaluated in field studies. Bromacil reduced photosynthesis to a greater extent in orchardgrass than Kentucky bluegrass turf. Foliage carbohydrates were depressed initially in bluegrass followed by recovery in 2 weeks to 1 1/2 months following bromacil application. Orchardgrass, however, did not recover. Application of 0.56 kg/ha bromacil each summer and fall for 2 years gave the best control of orchardgrass. During the second year, increase in foliage crude protein was observed in treated bluegrass. Bluegrass foliage yields were equal to or greater than the controls. Orchardgrass yields were drastically reduced by bromacil. Effective seedling orchardgrass control was obtained with minimal bluegrass injury at 0.14 to 0.28 kg/ha of bromacil. Bromacil treated areas were effectively fall-seeded with bluegrass approximately 8 weeks after a 0.56 kg/ha application, Rooting of bluegrass sod was not inhibited at the rates used for selective control of orchardgrass in bluegrass turf. In controlled environmental growth chamber studies, bromacil had no effect on germination of Merion Kentucky bluegrass or Virginia Common orchardgrass, but reduced the growth of emerging shoots of orchardgrass more than bluegrass. Fresh weight gain, root growth, and transpiration were reduced in orchardgrass plants at 0.125 ppmw bromacil whereas 1.0 ppmw gave reductions in bluegrass. Photosynthesis was inhibited initially in both grasses, however, bluegrass recovered in 6 days. Foliage carbohydrate content was greater and was affected less by bromacil treatment in bluegrass than orchardgrass. Root absorption and translocation of 2-¹⁴C-bromacil to the shoot was directly related to transpiration in both grasses. Bromacil was absorbed and translocated acropetally in sheath and foliar treatments in both grasses. Higher metabolic conversion of 2-¹⁴C-bromacil occurred in bluegrass as compared to orchardgrass with 1.0 ppmw treatment. The major metabolites were 5-bromo-3-(2-hydroxy-1-methylpropyl)-6-methyluracil and an unknown. Trace amounts of 3-sec-butyl-6-methyluracil and 5-bromo-3-sec-butyl-6- hydroxymethyluracil were also detected. Bluegrass tolerance to bromacil involves high carbohydrate levels in tissues, hydroxylation of bromacil, and rapid recovery of photosynthesis. / Ph. D.

The objectives of this research were to 1) evaluate the establishment and peak standing crop of Berber Orchardgrass (Dactylis glomerata var. "Berber"), Palestine Orchardgrass (Dactylis glomerata var. "Palestine"), and Sheep Fescue (Festuca ovina var. "Covar") ; 2) to assess establishment and production changes resulting from environmental gradients (elevation, slope, aspect, soil texture, precipitation, and resident annual community) across the foothill landscape; 3) develop a mathematical model that predicts site potential for restoration; and 4) evaluate the utility of Geographic Information Systems for creation and analysis of spatial data which identify site production potential. Sixteen sites were chosen which reflect the general character of the foothill rangelands in southwestern Oregon. A Randomized Complete Block design was used to select treatment arrangement on each site. Seeded treatments received both chemical (Glyphosate, Hoelon, and 2,4-D) and mechanical (residue removal) disturbance. Test species were seeded into three replications at each site. Each replication also included a non-treatment control. Standing crop data for test species and resident exotics were collected after three growing seasons. Berber orchardgrass did not establish at most sites and where establishment did take place production was less than 132 kgDM/ha. Palestine orchardgrass established on on a majority of the study sites and produced most aboveground phytomass at mid-elevations where coarser soil textures and deeper soil depths were common. Sheep fescue was the most successful of the three test species and did best on low elevation high clay sites. There was significantly (P=0.001) more phytomass produced by annual exotics on seeded plots than on undisturbed controls at most sites. Both Palestine orchardgrass and sheep fescue treatments significantly suppressed the annual exotics when compared to the Berber treatments. Generally, "Covar" sheep fescue can establish and successfully compete with exotics on heavier textured soils at low elevations. "Palestine orchardgrass is adapted to mid-elevation coarser soils. / Graduation date: 1995

Experiments were conducted to study the effect of gibberellic acid on palatability and digestibility of two grasses, orchard grass and Kentucky 31 fescue. The GA was applied as a spray, except one granular application, at rates of 18 to 72 gm./A. Sheep were used to test the grass for palatability and digestibility. In addition to proximate analysis of grass, data were obtained on soluble carbohydrate, cellulose and lignin contents. Chemical composition of orchard grass was not affected by GA treatment. The most consistent effect of GA on the chemical composition of fescue was a depression of protein content. Ash content was decreased slightly, but consistently. GA increased crude fiber in two experiments; did not affect it in three. Nitrogen free extract was increased slightly in three of the five tests. Cellulose was increased by GA in the summer and fall of 1960, but not in the spring. Lignin was increased in the spring of that year and decreased in the summer and fall. Ether extract and soluble carbohydrate contents were not consistently affected by GA. In general, chemical changes by GA were less than 5%. Orchard grass palatability was improved by GA. In two out of three trials with Kentucky 31 fescue, consumption of GA treated grass was about 38% less than for the control. Irrigation increased palatability, probably due to a large difference in moisture content of the grass. No chemical differences observed were consistently related to selection of grass by the sheep. Digestibility of dry matter in grass tended to be decreased by GA in four out of five experiments. These depressions were less than 5% and in only two cases were they significant. Digestibility of protein, crude fiber, nitrogen free extract and cellulose tended to be decreased and ether extract was made more digestible by GA. Due to the small changes in both digestibility and chemical composition caused by GA no clear-cut explanations could be given for the reduction of digestibility. The effect seems related to a slight protein reduction and in some cases to an increase in crude fiber and cellulose. Although a number of factors which may affect GA response (time after application, growth rate of grass, light intensity, temperature, etc.) have not been studied, it seems unlikely that this growth regulator will exert much effect on the factors controlling digestibility of grass under field conditions. The effect on palatability is more pronounced, but not consistent. The digestibility of fall grown fescue increased with age. This increase probably resulted from accumulation of soluble carbohydrates and decreases in crude fiber, cellulose, and lignin contents in the grass. / Ph. D.

The effects of three fertilization rates of N (0, 112 and 224 kg/ha) as ammonium nitrate and S (0, 34, and 67 kg/ha) as calcium sulphate on yield, chemical composition, digestibility and palatability of orchardgrass (Dactylis glomerata L.) , were studied in a field experiment. Treatments were applied in a randomized block design with a 3x3 factorial arrangement of treatments with four replications. Hay was harvested on 18 Aug. 1982 and fed to sheep in metabolism trials. One half of the initial amount of fertilizer was reapplied and forage was stockpiled. Stockpiled growth was ensiled on 6 Nov. 1982 and was fed to sheep in palatability trials. Fertilizer was reapplied at the initial rates on 27 Apr. 1983 and yield and mineral concentrations were determined on 6 June 1983. Dry matter yield increased in response to N (P<0.01). Nitrogen fertilization decreased NDF (P<0.05) ADF, cellulose (P<0.01) and total S (P<0.01) and increased nitrate-N (P<0.01) in hay and stockpiled growth. In stockpiled growth S increased ADF ( P<0.05) and cellulose quadratically ( P<0.001) at the 34 kg/ha rate. Sulphur increased ( P<0.05) No₃-N in hay but decreased (P<0.05) it in stockpiled growth. The N:S ratio was increased (P<0.01) by N fertilization and decreased (P<0.05) by S fertilization. Nitrogen and S had a quadratic effect (P<0.0001) on lactic acid and water-soluble carbohydrates in silage. Digestibility or palatability of silage was not influenced by N or S. / Master of Science

The effects of red clover (Trifolium pratense, L.), three levels of N (0, 224 and 448 kg•ha⁻1•yr⁻1, as a split application) and two levels of S (0 and 34 kg•ha⁻1•yr ) on the chemical composition and dry matter digestibility of an orchardgrass (Dactylis glomerata, L.) sward were studied. The treatments were replicated three times in a randomized block design with a split-plot arrangement of treatments. Crude protein content, in vitro dry matter digestibility and dry matter yield were increased (P<. 01) with increasing levels of N. Increasing levels of N decreased (P<.05) S content of orchardgrass. The inclusion of red clover did not have any significant effect on the components analyzed, probably due to a low proportion of red clover (approximately 8%) in the mixed sward. Application of S increased ( P<.05) the S content of orchardgrass and decreased N-to-S ratio at all levels of N application. Application of S increased (P<.05) the crude protein and in vitro dry matter digestibility, whereas neutral detergent fiber, lignin and hemicellulose were decreased (P<. 05). Nitrogen fertilization had a quadratic effect (P<.05) on in vivo digestibility of dry matter, acid detergent fiber and hemicellulose and a linear effect (P<.001) on apparent digestibility of crude protein. Inclusion of red clover increased (P<.01) in vivo digestibility of dry matter and hemicellulose, and decreased (P<.01) digestibility of acid detergent fiber and lignin. Application of S had no direct effect on in vivo digestibility of orchardgrass. A linear interaction (P<.01) between N and S was observed for dry matter and crude protein digestibility. Rumen fluid ammonia-N was increased (P<.05) and butyric acid concentration was decreased (P<.05) linearly by N fertilization. / Master of Science