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  • ItemOpen Access
    Epidemiology of reported scrapie in the United States: 1947-1991
    (Colorado State University. Libraries, 1993) Wineland, Nora E., author; Salman, M., advisor; Kimberling, Cleon V., committee member; Gould, Daniel H., committee member; Weber, Stephen, committee member
    Data collected in support of the United States Department of Agriculture (USDA) scrapie eradication program between 1947 and September 30, 1991 were evaluated to determine the presence of trends or patterns which might help further the understanding of natural sheep scrapie. The USDA records from 957 confirmed positive cases of natural scrapie in 581 flocks from 39 states were reviewed and compiled into a database. Possible host and management risk factors for scrapie such as age at death, within-flock mortality, breed, sex, sire and dam disease status, flock size, and location were examined. There were several significant findings from the study. The proportion of reported positive flocks in those states reporting positive cases showed a steady increase between 1965 and 1991. In addition, the average flock mortality showed a slight increase between 1947 and 1991. These increases did not seem to be directly related to any changes in the USDA eradication program. The average age at death for confirmed cases was 43.6 months. Rams died of scrapie an average of five months younger than did the ewes. This difference was statistically significant, but likely due to the small numbers of rams included in the study. There were insufficient numbers of twins (26 pairs) to allow any significant conclusions to be drawn. There were no statistically significant differences between age at death for the eight geographical regions or the various sheep breeds affected. The Suffolk breed comprised 88% of the reported cases, and Hampshire sheep accounted for 6% of the cases. Attempts were made to further define the role of vertical transmission in natural scrapie. The scrapie disease status of the sire had no appreciable effect on the age of death of positive offspring. The scrapie disease status of the dam had a detectable effect with positive offspring from positive dams diagnosed at a significantly younger age than positive offspring from other dams. Unfortunately it was not possible to determine when a positive dam might begin shedding the scrapie agent and consequently present a threat to her offspring. All of the positive dams in the study gave birth to their positive offspring in flocks where there were other active cases of scrapie which might have been the source of infection for the offspring. The source of infection could not be determined for over half of the reported cases. Several possible explanations for this situation were presented. Failure to detect the sources of infection may in part be responsible for the apparent increase in the magnitude of the scrapie problem in the United States. Data quality and consistency was a major issue for this study. The records available from the technical program staff of USDA contained varying amounts of information about each of the positive animals and flocks. In addition to variation in the records, the eradication program itself went through several phases during the study period. These different phases may have had multiple effects on the levels of disease reported to USDA. Unfortunately these effects could not be measured or corrected for in the analysis.
  • ItemOpen Access
    Archaeological investigations of high altitude sites near Monarch Pass, Colorado
    (Colorado State University. Libraries, 1990) Hutchinson, Lewis A., author; Eighmy, Jeffrey, advisor; Benedict, James B., committee member; Leyendecker, Liston, committee member
    The tundra and upper forest border north of Monarch Pass. in the central Colorado Rocky Mountains. contains a cluster of twelve sites. One of the sites. Water Dog Divide Game Drive, is an extensive system of rock alignments and associated hunting blinds. This site and other smaller systems in the Monarch site area are at present the southernmost documented examples of prehistoric timberline game drives along the Continental Divide. Cultural materials include projectile points. other flaked tools, groundstone and a broken ceramic vessel. Temporal periods indicated are 3000 B.C. to the historic. Two hunting blinds were excavated and three radiocarbon dates were obtained with corrected dates ranging from 900 A.D. - 1640 A.O. Four of the rock walls in the largest drive site contain a number of remnant wooden posts or sewels apparently used to help delineate the rock walls. It is hypothesized that the area was utilized on a seasonal basis to camp and communally hunt large game animals (bison, mule deer, elk. and mountain sheep). The sites may have been visited by peoples from the Plains. Great Basin. and Southwestern culture areas.
  • ItemOpen Access
    Genetic relationships between sex-specific traits in a crossbred beef cattle population
    (Colorado State University. Libraries, 1993) Speer, Nevil, C., author; Brinks, James S., advisor
    Data used were obtained from the Fort Keogh Livestock and Range Research Laboratory (LARRL), Miles City, Montana. Data were from a crossbreeding experiment involving Hereford, Angus and Charolais cattle collected from 1962 to 1977. Traits studied and considered separate with respect to sex, included male and female birth weight (BWM and BWF), weaning weight (WWM and WWF), and postweaning average daily gain (ADGM and ADGF). Other traits studied were average adjusted mature weight (MW) of cows and fat thickness (FT), ribeye area (REA), yield grade (YG), quality grade (QG) and days on feed (DOF) of bulls and steers slaughtered at a weight constant endpoint of 1000 - 1050 lb. Multi-trait sire-maternal grandsire REML analyses were performed on straightbred and crossbred Hereford, Angus, and Charolais cattle. Observations on 2888 animals contributed to development of the A-inverse which represented relationships among 138 sires and maternal grandsires. Models for BWM, BWF, WWM, WWF, ADGM, ADGF, and MW analyses models included birth year, age of dam (2, 3, 4, 5+) and linear regression on weaning age. The DOF analysis model included birth year, age of dam, sex of calf (bull vs steer), age of dam-sex of calf interaction and linear regression on weaning age. Carcass trait (FT, REA, YG, QG) models included birth year, age of dam, sex of calf, age of dam-sex of calf interaction and linear regression on carcass weight. Linear regressions on individual breed percentage, combined reciprocal cross percentage (individual heterosis), dam breed percentage and dam combined reciprocal cross percentage (maternal heterosis) were also included in all models for analyses of all traits of interest. Correlations between direct components of birth weight, weaning weight, and postweaning average daily gain considered separately between male and female calves were .93, .90 and .74 respectively. The correlation between direct components of MW and DOF was -.66. Correlations between direct components of MW and carcass traits were -.54, -.18, -.18, and .41 for FT, REA, YG and QG, respectively. Correlations between maternal components of birth weight, weaning weight, and postweaning average daily gain considered separately between male and female calves were .86, .98 and .42, respectively. The correlation between maternal components of MW and DOF was -.71. Correlations between maternal components of MW and carcass traits were .40, .10, .08, and -.06 for FT, REA, YG and QG, respectively. Correlations between mat-dir and dir-mat of the same traits studied were moderate and ranged from -.44 to .47. Predictions of correlated responses in mature weight per standard deviation of direct response in male carcass traits were -32 lb, -13 lb, -10 lb, and 31 lb respectively for FT, REA, YG and QG. Correlated response predictions indicate selection for improved carcass cutability on a weight constant basis (increased leanness and decreased yield grades) would increase mature weight while selection for increased ribeye area and decreased quality grade scores (favorable) on a weight constant basis would result in decreased mature weights of females. Strong selection pressure for leanness may be antagonistic to commercial beef producers since results suggest sires selected on the basis of reducing fat in steer progeny also produce females that are larger at maturity when cattle are slaughtered at a constant weight endpoint. It should be noted, however, relationships between carcass traits and mature weight may differ when cattle are slaughtered at a constant age endpoint.
  • ItemOpen Access
    Sequence stratigraphic framework for top seal development: examples from the Skull Creek and Graneros shales, Denver basin
    (Colorado State University. Libraries, 1999) Edwards, Kimberly, K., author; Sutton, Sally J., advisor; Ethridge, Frank G., advisor; Almon, William R., committee member
    In general, the distal open marine shelf setting, typified by the Graneros Shale produces a rock with a greater and more uniform seal capacity relative to the rocks of a proximal open marine shelf setting, such as those of the Skull Creek Shale. A distal setting, which usually corresponds to the time of maximum transgression, may produce better seals because there is less coarse clastic sediment input, which allows slow deposition of clays from suspension to be the dominant depositional process. In this study, the higher capacity seal rocks occur in the upper parts of the TST, either within the condensed section or below it. The Skull Creek locations show seal occurrence to be stratigraphically higher on depositional topographic highs, and lower in areas that were topographically low at the time of deposition. Top seal capacity was quantified with mercury injection capillary pressure (MICP) analysis. Other physical characteristics of these marine shales were studied but only porosity, permeability, total clay, and hydrogen index consistently demonstrated a significant correlation with seal capacity in both units. Shales that are well laminated with a high percentage of total clay and/or total organic carbon with a type I-II (marine) kerogen may or may not qualify as the best seal. Top seal capacity may be more a function of rock fabric rather than mineralogy. For example, two samples may have exactly the same amount of quartz, as shown by XRD analysis, but thin section examination reveals that the majority of quartz in one sample is present as grains and in the other sample as cement. Samples with cement usually provide a better seal because they decrease the pore throat diameter, thus increasing the amount of hydrocarbons that can be trapped. Seal quality in both the Skull Creek and Graneros Shales is quite variable throughout each of the facies within the TST deposits.
  • ItemOpen Access
    Influence of abiotic and biotic factors on the response of benthic macroinvertebrates to metals
    (Colorado State University. Libraries, 1995) Kiffney, Peter Michael, author; Clements, Will, advisor; Fausch, Kurt D., committee member; Kondratieff, Boris C., committee member; Chapman, Phillip, committee member
    Stream ecologists are well aware that chemical, biological, and physical characteristics of lotic systems vary spatially and temporally. With this in mind, I designed a series of experiments and field studies to examine the role of spatial variation in stream benthic macroinvertebrate communities in response to metals. Specifically, I tested the hypothesis that stream invertebrate communities from pristine streams of different size and altitude varied in their response to metals. To evaluate how metals affected biotic interactions, I manipulated invertebrate density, predation intensity, and metals in stream microcosms. Using stream invertebrate communities, I also designed an experiment and field survey to identify reliable bioindicators of metal contamination in western streams. Results from microcosm experiments and field studies showed that benthic invertebrate populations from high-altitude streams were more sensitive to the effects of metals than invertebrate populations from low-altitude streams. For example, Baetis sp. and Rhithrogena hageni from Little Beaver Creek (LBC), Colorado, (high-altitude stream) were significantly more sensitive to zinc than the same species from the South Fork of the Poudre River (SFP) (low-altitude stream) in stream microcosms. Results from field surveys showed that densities of most groups of aquatic insects (e.g., Ephemeroptera, Plecoptera, Trichoptera) were lower at high-altitude metal contaminated streams than those same groups at low-altitude streams. Other factors, such as variation in water temperature or nutrient concentrations between high- and low-altitude streams, could be lll responsible for these differences. However, because invertebrate responses were similar under controlled and field conditions, I hypothesize that differences in abundances between reference and contaminated locations was a result of metals. To determine if body size contributed to the variation in sensitivity of insects to metals, size measurements were made on species collected from LBC (high-altitude) and SFP (low-altitude). Measurements were also made on species from control and metal-treated stream microcosm. Most species were smaller at LBC (high-altitude stream) than the same species from SFP (low-altitude stream). For example, the mayfly Baetis tricaudatus and the caddisfly Arctopsyche grandis were significantly larger at SFP than LBC. In addition, insect body size was larger in metal-dosed microcosms than in controls. Brachycentrus sp., B. tricaudatus, R. hageni, Eohemerella infrequens, and P. badia were significantly larger in metal-treated microcosms than in controls. Logistic regression indicated survival in metal-dosed microcosms was less for small individuals than for larger individuals of the same species. These results suggest that some insect species from high-altitude streams were smaller than those from low-altitude streams, and that survival was greater for larger lifestages. Thus the variation in response of macroinvertebrates between different altitude streams observed in earlier studies may be due to differences in body size. The effects of low levels of metals (half the chronic levels of Cd, Cu, and Zn) on some species varied in relation to invertebrate density (low and high density) and invertebrate predation (no predators added and predators added). The abundance of Hydropsyche sp. was significantly lower in metal-dosed, high density treatments than in control, high density treatments. Moreover, the effects of an invertebrate predator (Hesperoperla pacifica) on Hydropsyche sp. was significantly greater in metal-dosed microcosms than in controls. These results suggest that metals interact with biotic factors to influence stream invertebrate community structure, and that effects occurred at metal concentrations lower than chronic criteria value. Toxicity experiments in stream microcosms showed that the abundance and species richness of aquatic insects were significantly reduced at 1x, 5x and 10x the United States Environmental Protection Agency chronic levels of cadmium, copper, and zinc (1x=1.1, 5.0, and 110 μg/L Cd, Cu, and Zn, respectively). Mayflies were the most sensitive group, as the abundance of Baetis sp. and Rithrogena hageni were significantly reduced in the Ix treatment. The response of Drunella grandis was size dependent, as small lifestages were significantly more sensitive than large lifestages. Stoneflies were also affected, but their response was more variable with abundances of some species (Pteronarcella badia) being reduced in the Ix treatment, whereas other species were unaffected (Sweltsa sp.). Heptageniid mayflies were consistently less abundant downstream of sources of metal contamination in the Arkansas and Eagle rivers, whereas the response of other measures were more variable. For instance, species richness and total density were greater at a metal-contaminated site on the Arkansas River compared with an upstream reference site. Therefore, results from this experiment and field survey suggest that changes in abundance of heptageniid mayflies may provide a reliable indicator of metal-contamination in western streams.
  • ItemOpen Access
    5000 years at Crow's Roost in eastern Colorado
    (Colorado State University. Libraries, 1992) McDonald, Robert A., author; Jennings, Calvin H., advisor; Leyendecker, Liston, committee member; Zier, Christian, committee member; Theodoratus, Robert, committee member
    Many areas on the high Plains of eastern Colorado have had little prehistoric research conducted on them. One of the areas where there is insufficient information about local prehistory is the area between the two major river drainages, the Arkansas and the Platte. Crow's Roost, a large sandstone cliff, located east of Colorado Springs, Colorado, is situated near this dividing line, known as the Palmer Divide. A series of prehistoric sites at Crow's Roost has been investigated over a period of five years by the Anthropology Department, University of Colorado at Colorado Springs. These investigations indicate that there has been prehistoric occupation at this locality dating back at least 5400 years. This study presents an interpretation of the culture history, and of recent paleoclimatic fluctuations for this locality.
  • ItemOpen Access
    The bighorn sheep of Battlement Mesa - a low elevation population
    (Colorado State University. Libraries, 1991) Cunningham, Mary Louise, author; Bailey, James A., advisor; Alldredge, A. William, committee member; Lehner, Philip N., committee member
    I studied bighorn sheep on Battlement Mesa, Colorado, from 12/88 to 7/90, to determine present and past herd status and distribution, so that 1) management options are clarified and 2) future management activities may be evaluated. I studied the herd by tracking 1 radio-collared ewe and obtaining visual observations and by systematically sampling study area units for sheep, sheep sign, potential competitors, potential predators and sheep carcasses. I recorded water sources that were encountered. I developed an historic perspective of the herd by searching agency files and local newspapers and interviewing local residents. The herd numbered up to 200-250 animals in the early 1900s and declined to an estimated 50 animals by 1970. Minimum herd sizes during 1989 and 1990 were 23 and 26, including lambs, respectively. Since 1961, the herd has abandoned approximately 56 km2 of historic range in the Mamm Peaks area. The herd decline corresponded with probable vegetation changes on Battlement Mesa, intensive livestock grazing through the 1950s, reports of poaching and an increasing elk herd. Sheep remained on the western portion of the range during winter and spring, 1989. Ewe/juvenile groups migrated to Anderson and Durant Gulches between 5/15-7/15/89 for lambing. Rams were more dispersed and in groups of 1-3, except during the rutting season. Ewe/juvenile group size ranged from 1-13. During dry months, (7/89, 8/89, 6/90) sheep concentrated in Anderson and Durant Gulches where a free-flowing spring and a seep were located. Bighorn sheep on Battlement Mesa appear limited by dense mountain shrub stands which separate all productive meadows from escape terrain and cover historic migration routes. A significantly greater use of the shale slope habitat contributed most to rejecting the null hypothesis that sheep use habitat types in proportion to their availabilities on Battlement Mesa. Sheep remained on shale slopes most (75% of all observations) of the time, using scattered grasses, forbs and shrubs for forage and seeps for water. Intensive and long term habitat management for bighorn sheep on Battlement Mesa is required. I suggest a 4-phase management program to improve existing range and later to reestablish and maintain historic migration corridors to productive historic summer range. Without management to improve existing conditions, this small, unique herd will remain static or decline.
  • ItemOpen Access
    Feed zone micromixing and its effect on continuous cultures of Saccharomyces cerevisiae
    (Colorado State University. Libraries, 1995) Mondani, Paul, author; Loftis, J. C., advisor
    Inadequate mixing is known to be a common problem in the scale-up of bioprocesses, often leading to decreases in yield and productivity. To investigate the role of nutrient dispersion in continuous cultures, growth medium was fed into a laminar flow section of a loop that recirculates broth from a laboratory scale bioreactor. The intensity of micromixing at the feed site could be controlled by varying the axial distance a static mixer was placed upstream of the site. The intensity of the turbulent wake shed by the mixer was quantified by laser Doppler velocimetry and the Bourne dye reaction. By decreasing the size of the smallest turbulent eddy in the feed zone, less of the population is exposed to regions of either inadequate or excessive substrate concentrations. Yield vs. dilution rate curves were obtained through various mixing and feeding strategies. Reduced mixing was shown to delay the onset of the Crabtree effect and therefore improve the bioreactor's productivity.
  • ItemOpen Access
    Parent material-topographic-management controls on organic and inorganic nutrients in semiarid soils
    (Colorado State University. Libraries, 1984) Aguilar, Richard, author; Heil, Robert D., advisor; Barbarick, K. A., committee member; Schumm, S. A., committee member; Franklin, W. T., committee member
    Paired native grassland and cultivated landscapes were characterized to evaluate parent material and topographic controls on organic matter and phosphorus along catenary sequences in southwestern North Dakota. Site selection was based on parent material (sandstone, siltstone, and shale residuum), similar cropping history (44-yr wheat-fallow rotation), and uniform range management. Parent material-soil process relationships were established by evaluating chemical and physical data for soil profiles at the native-summit landscape segments on the three contrasting parent materials. The effects of topography on the amounts and vertical distribution of organic matter and phosphorus were evaluated by studying soil profiles at various geomorphic landscape components along the catenas. The effects of 44 years of cultivation were evaluated by comparing cultivated and virgin soils at each landscape segment using the soils on native pasture as benchmarks. The finer textured soils weathered in shale were found to have much higher levels of organic C, N and Total P. Soils weathered in sandstone were found to have more uniform decreases in organic matter with profile depth and the highest quantities of organic P. On the native pastures, quantities of organic matter were much higher in the lower landscape segments because of higher moisture contents and/or the deposition of organic matter-enriched soil. Soils at lower landscape segments (lower backslopes, footslopes) have been enriched with Total P at the expense of soils at the upper portions of the catenas. Changes in organic and inorganic soil constituents resulting from cultivation were found to vary as a function of parent material and topography. Mineralization losses of organic constituents appear to have been higher in the sandstone soils. The fine-textured shale soils, which appear to have a large proportion of highly humified, clay associated organic matter, lost the lowest quantities of organic constituents relative to total soil loss. Losses of organic matter were generally lower at the lower landscape segments in all three sites, reflecting soil deposition. Redistribution of soil material by both mechanical (tillage practices) and natural processes (wind and water erosion) must be considered when evaluating cultivation-induced changes in soil properties along catenary sequences.
  • ItemOpen Access
    Interference of apple seedling growth by green foxtail
    (Colorado State University. Libraries, 1984) Omezine, Abdessatar, author; Wallner, Stephen J., advisor; Zimdahl, Robert L., committee member; Rogoyski, Matthew, committee member
    Because of the documented benefits of cover crops in orchards, the interactions of one potential candidate-green foxtail (Setaria viridis L . Beauv.)-with apple seedlings (Malus domestica L.) have been investigated. Two possible interference mechanisms have been studied under greenhouse conditions: competition and allelopathic effects of green foxtail on apple seedling growth. Inhibition of apple seedling growth by green foxtail was recorded only in interference experiments where competition for water or nutrients was a present factor. No inhibition was detected when competition was removed or minimized in a hydroponic system. The incorporation of green foxtail root debris into soil mixture did not result in inhibition of apple growth. Thus, competition for water was the most likely reason for inhibition of apple seedling growth by green foxtail. The presence of green foxtail did not affect dry matter distribution in apple seedlings when water and nutrients were equally available to both plants. Studies of allometric parameters anatomical indices suggested that green foxtail roots did not release any allelopathic chemicals. Green foxtail might be used as cover crop in apple orchards when competition for water and nutrients is minimized. Elimination of competition is a difficult and expensive task and is often impossible in the field. However, the reduction of competition can be made by using strip herbicidal treatment in the tree rows.
  • ItemOpen Access
    Cultural studies of greenhouse grown Eustoma grandiflorum
    (Colorado State University. Libraries, 1984) Azrak, Mohamed F., author; Goldsberry, Kenneth L., advisor; Baker, Ralph, committee member; Workman, Milton, committee member
    Change in photoperiod had no affect on flower initiation of Sakata F-1 hybrid E, grandiflorum; however, plant flower buds developed faster, had increased stem length, greater number of bud nodes, and more plant fresh and dry weight when exposed to day growing temperature and relative humidities of 22° C and 70%, compared to 17° C and 30-50% respectively. Sakata plants grown in volcanic scoria, gravel, and idealite had better growth and production than those in soil medium. The removal of terminal shoots at the fourth, fifth or sixth leaf pairs above the base, had no effect on growth, however, the removal of the growing tip only, reduced the flowering time by 10 days. The Weddle hybrid of E. grandiflorum was more productive and had larger stems than the Sakata hybrids. Both hybrids had two definite flowering cycles per year, one from May through June, and a second from August to mid-October. The vase life of both hybrids ranged from 8 to 18 days, but was not increased by preservative addition of 8-hydroxyquinoline citrate, (8-HQC), plus sugar. E. grandiflorum was attacked by red spider mite (Tetranychus urticae) and white fly (Trialeurades vaporariorurn) and was highly susceptible to Rhizoctonia solani and Fusarium spp.
  • ItemOpen Access
    Carbon dioxide levels in the plant microenvironment as influenced by a poly-coated paper mulch
    (Colorado State University. Libraries, 1983) Tarter, Cheryl K., author; Moore, Frank D., III, advisor; Wallner, Stephen J., committee member; Smith, D. D., committee member
    Effectiveness of carbon dioxide (CO2) enrichment using a polyethylene coated black paper mulch, incorporated nitrogen and wheat straw particles, and field CO2 release was investigated. A mulch covering or mulch over incorporated plant residue, such as straw, has been suggested as a possible means of CO2 enrichment which results from trapping the CO2 evolved from the soil. This idea was tested using Great Lakes Mesa 659 lettuce seedlings in growth chambers and in an outdoor setting. Carbon dioxide concentrations at the base of the plants and at a 5 cm depth in the root zone were greater in mulched and mulched straw treatments. Non-mulched straw did not increase surface CO2 concentrations. Growth of mulched plants in the chambers was approximately 80% greater than that of non-mulched plants. Mulched plants in the outdoor study had a growth increase of about 13% when compared to non-mulched plants. Increases in growth of mulched plants were attributed to greater CO2 levels, since soil moisture levels and temperatures were similar in all treatments. Straw suppressed growth and would not be recommended as a CO2 source. Mulch applied over CO2 release lines in the field was found to be an effective means of CO2 enrichment of a lettuce canopy by creating a physical barrier to rapid air exchange, thereby concentrating released CO2 under the mulch. Mulch over a release line more than tripled CO2 concentrations near the soil surface when compared to CO2 release with no mulch covering or CO2 supplement. Significant enrichment levels were maintained to 25 cm above the soil surface on still days by means of a mulched CO2 release line. Subsurface CO2 concentrations were increased by the application of mulch and averaged 857 ppm which was considered non-phytotoxic. The effect on soil CO2 levels from the release line was negligible. Inconclusive results in plant response suggest further study is warranted.
  • ItemOpen Access
    Interaction between light, nitrogen and mycorrhizal fungi on photosynthesis of ectomycorrhizal pine
    (Colorado State University. Libraries, 1983) Ekwebelam, Sebastian A., author; Reid, C. P. P., advisor; Doxtader, Kenneth G., committee member; Wallner, Stephen J., committee member; Hunt, H. William, committee member
    The importance of mycorrhizae to the physiological functions of plants is relatively well documented. Despite the obvious benefits of mycorrhizae for the enhancement of seedling growth, study of the relationship between applied cultural practices, such as shading, fertilization and mycorrhizae formation, and growth and photosynthesis of containerized nursery stock has been limited. The long-term objective of the present study, therefore, was to gain a more complete understanding of how the aggregate factors of light, nitrogen fertilization and mycorrhizae formation influence growth and photosynthesis of containerized seedlings, aimed at optimizing seedling production in a nursery environment. Seedlings of lodgepole pine (Pinus contorta Dougl.) were grown for 16 weeks without ectomycorrhizae in the greenhouse at 3 level s of irradiance (high, medium and low) by use of shadecloth, and ammonium nitrate (3, 62 and 248 ppm N) . Measurements at 5, 10 and 16 weeks of age indicated that biomass increased significantly with increasing levels of irradiance and nitrogen over the ranges studied. Although root/shoot ratios increased from low to high irradiance at each harvest, nitrogen application resulted in increased ratios from 3 to 62 ppm N, but decreased ratios at 248 ppm N. Nitrogen and phosphorus concentration generally decreased with increase in irradiance, but total N content and photosynthesis per unit leaf area generally increased from low to high levels of both irradiance and nitrogen. In a mycorrhizal fungi inoculation study, lodgepole pine seedlings were grown for 10 weeks without ectomycorrhizae at the aforementioned 3 levels of irradiance and nitrogen. At 10 weeks, mycorrhizal treatments, inoculation with either Pisolithus tinctorius or Suillus granulatus, were superimposed on the light and nitrogen treatments, and the seedlings were grown for an additional 6 weeks. Mycorrhizae formation increased with increase in irradiance, while fertilization with 62 ppm N resulted in greater mycorrhizae formation than either 3 or 248 ppm N. Further, inoculated plants had significantly greater biomass and nutrient contents than nonmycorrhizal seedlings. Inoculation with P. tinctorius and granulatus resulted in photosynthetic rates, 1.87 and 1.85 mg CO2dm-2h-1, respectively, significantly greater than nonmycorrhizal plants (1.41 mg CO2dm-2h-1). Although the increase in growth of the mycorrhizal seedlings was associated with increased photosynthesis, the magnitude of this response depended on specific combinations of irradiance and nitrogen fertilization. These results emphasize the importance of the interactions among irradiance, nitro gen fertilization, and mycorrhizae development in the growth of containerized seedlings.
  • ItemOpen Access
    Desiccation and freezing tolerance of embryonic axes and lateral buds of Citrus SPP: implications for germplasm conservation
    (Colorado State University. Libraries, 1999) Santos, Izulmé R. I., author; Stushnoff, Cecil, advisor
    To view the abstract, please see the full text of the document.
  • ItemOpen Access
    Impact of irrigation regime on trees and turfgrass in a landscape setting
    (Colorado State University. Libraries, 1999) Findley, Douglas Alan, author; Wallner, Stephen J., advisor; Jacobi, William R., committee member; Stushnoff, Cecil, committee member; Koski, Anthony J., committee member
    The response of Gleditsia tricanthos inermis 'Skyline', Fraxinus pennsylvannica 'Patmore', and Paa pratensis 'Livingston' grown in a landscape setting to three irrigation regimes was evaluated. Irrigation regimes were based on evapotranspiration (ET) and consisted of deficit, (40% ET), replacement, (80% ET), or excessive, (160% ET) amounts of water applied throughout the growing season. These irrigation regimes had no affect on leaf weight, area, percent moisture, height, caliper, or cold hardiness low temperature exotherms (LTE). Leaf water potential of the trees, a measure of plant water stress, was lower with decreasing application of water. Fall color development was affected only for Fraxinus pennsylvannica 'Patmore'. Deficit irrigated trees initiated fall color two weeks earlier and reached maximum fall color one week prior to trees under excessive irrigation. Turfgrass clipping weight and percent moisture was reduced in both studies with decreasing irrigation levels. Turfgrass irrigated at 160% ET remained dark green, and continued growing throughout the summer, producing large quantities of clippings. Replacement irrigated turfgrass maintained a dark green color, highly desired by landscape managers and homeowners, but clipping quantities were significantly reduced compared to excessively irrigated turfgrass. When Paa pratensis was maintained at 40% ET, it entered drought induced dormancy three to six weeks after treatment initiation. The turfgrass was light green, and bare soil was visible through the canopy in some portions of the plots providing an ideal location for weed seeds to germinate. Results from these studies indicate that irrigation regime has a limited affect on tree growth and development after one growing season, however the long term impact after several years of similar irrigation regimes may be more important for disease and insect outbreaks. Turfgrass growth is affected by irrigation regime in such a way that landscape managers can reduce clippings by reducing irrigation levels and still maintain acceptable quality turfgrass.
  • ItemOpen Access
    Potato clone variation in blackspot susceptibility, extract darkening, and some chemical factors
    (Colorado State University. Libraries, 1983) Thornton, Michael Kent, author; Workman, Milton, advisor
    Six potato clones were analyzed with respect to tissue extract darkening, phenolic content, dry matter, and potassium content to determine if these properties were related to differences in blackspot susceptibility. Clones differed significantly in tissue extract darkening, dry matter and potassium content, but not phenolic content. Differences in tissue extract darkening were not significant when cell wall fragments were filtered. The potential of the tissue to darken, as determined by tissue extract darkening studies, was not consistently related to blackspot susceptibility. Clones with low tissue extract darkening darkened most in response to addition of substrate (catechol). Phenolic content (tyrosine and o-diphenols) were more consistently related to tissue extract darkening than to blackspot susceptibility. Dry matter content was most closely related to blackspot susceptibility, but did not account for all differences. Potassium content was not related to blackspot susceptibility. Changes in ascorbic acid content of bruised and nonbruised tissue of four potato clones were followed over time to determine if they were related to blackspot susceptibility. Ascorbic acid content of bruised and nonbruised tissue of three clones decreased over 24 hours. However, the ascorbic acid content of one clone increased during this same period. These changes were not related to blackspot susceptibility. Differences in ascorbic acid content between bruised and nonbruised tissue of the same tuber were significant in 3 of 4 clones but were not related to blackspot susceptibility.
  • ItemOpen Access
    Greenhouse production of fresh market basil
    (Colorado State University. Libraries, 1998) Succop, C. Elizabeth, author; Newman, Steven E., advisor; Brick Mark A., committee member; Basham, Charles W., committee member; Panter, Karen L., committee member
    Common green sweet basil Ocimum basilicum L., is a viable crop for fresh market greenhouse production due to its high value and increasing demand. Organically and hydroponically grown products conserve natural resources while providing a marketing edge and sales advantage for producers. Greenhouse growing methods fulfill a need for locally grown organic produce during the off-season. Data on greenhouse production of fresh market basil is needed by Colorado growers for efficient and profitable production. Growing/irrigation systems had an effect on the greenhouse production of fresh market basil. Comparison of bag mix, perlite, and rockwool growing systems were made within organic and salt-based fertilizer treatments. Differences were found among growing systems for total harvest per plant, final plant dry weight and final plant height depending on the fertilizer treatment and the summer/fall 1996 or spring/summer 1997 growing season. Comparisons were also made between fertilizer treatments within growing media. Basil yield in the organic fertilizer compared to the conventional, salt-based fertilizer depended on the growing system, the week of harvest, the Fusarium infection in 1997, and the growing season. Variables of interest were weekly harvested fresh weights; weekly harvested dry weights, and weekly chlorophyll readings with a SPAD meter. Nitrate nitrogen measurements and a complete plant leaf tissue analysis were taken at the termination of each study. Additionally, organoleptic taste test panel members performed a triangle difference test between the organically fertilized plants and the salt-based fertilized plants for the perlite, bag mix and rockwool growing systems. Panel members also performed a preference test between organically fertilized and conventionally fertilized plants. This research determined that basil can be successfully grown hydroponically and organically in a Colorado greenhouse. The physical appearance and health of the plants declined after four months of weekly harvesting in the 1996 and 1997 studies. During the last month of production of the 1996 study, the fresh weight and dry weight yields decreased for all growing systems reflective of the decreasing light intensities. The 1997 study shows an upward trend in fresh weight and dry weight yields for all growing systems reflective of increasing photoperiod reactions.
  • ItemOpen Access
    Effect of ethephon and irrigation deficit on color enhancement of Vitis vinifera L. as determined by anthocyanin content of wine
    (Colorado State University. Libraries, 1999) Poxleitner, Marianne, author; Stushnoff, Cecil, advisor
    Three experiments were performed on Colorado grown grapevines to test irrigation deficit and/or ethephon application on the color enhancement of red wines. In the first experiment, drip irrigated Pinot noir vines were exposed to an irrigation deficit in the second half of the growing season. Vine water potential was monitored with a pressure bomb, and resulting wines were analyzed spectrophotometrically for anthocyanin content. No significant increase in anthocyanins was found between the wines from the control and treatment groups. The second experiment used Sangiovese grapevines to test the application of a 750 ppm ethephon spray at eight weeks and nine weeks post anthesis against a control. Spectrophotometric analysis of the wines showed significant increases in anthocyanin content of 16.7% and 41.7% above the control for the eight and nine week post anthesis applications, respectively. The third experiment utilized furrow irrigated Pinot noir vines to test the effects of ethephon on vines subjected to a late season water deficit. A pressure bomb was used to monitor vine water potential, a neutron probe was used to monitor soil moisture, and the wines were analyzed spectrophotometrically. A significant increase in anthocyanin content was found due to the ethephon application at nine weeks post anthesis to the vines subjected to the water stress. A final experiment was conducted to observe the differences in color between Pinot noir and Merlot wines from different Colorado wineries. In addition, the color variation between different cultivars of wines from the Orchard Mesa Research Center was also investigated. Significant differences were found between the Pinot noir wines as well as the Merlot wines, and between the various cultivars analyzed.
  • ItemOpen Access
    Characterization of Alstroemeria species and cultivars using random amplified polymorphic DNA (RAPD) analysis
    (Colorado State University. Libraries, 1997) Picton, Deric D., author; Hughes, Harrison G., advisor; Ward, Sarah, committee member; Stushnoff, Cecil, committee member
    The characterization of Alstroemeria has not been effective through the use of conventional morphological markers. This is mainly due to the confused status of many of the species. Breeding of Alstroemeria has involved interspecific crosses as well as the use of mutagens and chromosome doubling for the creation of cultivars. Through the use of molecular techniques, in particular random amplified polymorphic DNA (RAPD) analysis, it is possible to uniquely characterize the species and cultivars. Fifteen species and hybrids along with 25 cultivars were examined using RAPD analysis. Four primers were eventually used for the analysis. All amplification products were separated using a 5% polyacrylamide gel and stained with silver nitrate for maximum differentiation of the fragments. The four primers yielded 73 amplification products which were polymorphic. When analysed using cluster analysis, all species and cultivars were uniquely characterized and putative parentages of many of the cultivars were determined.
  • ItemOpen Access
    Characterization of chickpea (Cicer arietinum L.) accessions using molecular techniques
    (Colorado State University. Libraries, 1998) Hamdaoui, Fatiha, author; Hughes, Harrison G., advisor; Johnson, Duane, committee member; Nabors, Murray, committee member; Towill, Leigh E., committee member
    The productivity of chickpea has not been markedly improved through conventional breeding. The main problem for increasing yield is the susceptibility of the plant to the disease caused by the ascomycete Ascochyta rabiei. Because genetic markers may speed up chickpea breeding for resistance to ascochyta blight, isozymes and RAPD techniques have been applied to 56 chickpea germplasm lines which have been screened against ascochyta blight in the field and at the greenhouse in Morocco. Artificial inoculation at three locations, resulted in none of the lines evaluated being immune, seven entries were resistant and the remaining were tolerant or susceptible under Morocco conditions. Two hundred primers for RAPD assay and 15 enzymatic systems were assayed. The fifteen enzymatic systems tested were almost monomorphic and were not able to discriminate among the tested lines. Among the 200 primers tested only 6 primers yielded polymorphism. Forty- one amplification products were produced and among them four were associated with disease resistance to ascochyta blight. RAPD procedure with polyacrylamide gels differentiated among the resistant and susceptible cultivars and produced more polymorphisms than RAPD using agarose gels.