Theses and Dissertations

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Open Access
A case study evaluation of edible plants curriculum implemented in an elementary school
(Colorado State University. Libraries, 2014) Graves, Leila, author; Hughes, Harrison, advisor; Balgopal, Meena, advisor; Bunning, Marisa, committee member; Krishnan, Sarada, committee member
The main purpose of this study was to describe elementary teachers' attitudes and perceptions toward plant science. The secondary purpose was to create an edible plant curriculum as a vehicle for integrating STEM and 21st Century skills into Common Core Content. Results indicate that teachers and STEM coordinators did find the curriculum to be effective in teaching the interdisciplinary standard-based and inquiry based content and skills targeted. Additionally, the curriculum development process produced a hybrid design framework that facilitated the creation of life science content as a vehicle for integrating STEM into common core content. However, several significant barriers will need to be overcome with regard to the teachers', STEM coordinators' and administrators' perception that plant science and nutrition literacy are "special" content activities versus important STEM content.
Open Access
A cross-cultural comparison of visual landscape preferences for the natural environment
(Colorado State University. Libraries, 1994) Mohd-Shariff, Mustafa Kamal Bin, author; Haas, Glenn E., 1951-, advisor; Wallace, George E., committee member; Lakey, Jeff, committee member; Taylor, Jonathan G., committee member
The purpose of this study was (1) to identify significant differences in the landscape preferences for the natural environments of Caucasian, Hispanic, Black, Native, and Asian American students at Colorado State University, (2) to identify and compare the underlying perceptual dimensions of their preferences, and (3) to compare the effectiveness of the Kaplans' Informational Processing Model of Environmental Preferences predictors on the landscape preferences of each group. The study found that all groups rated the mountain category highest and the grassland category lowest. However, within categories, Native Americans and Caucasians rated mountain and grassland categories significantly higher than Blacks or Asians. Though there were no statistically significant differences, Blacks and Asians rated the city park category relatively higher than Native Americans and Caucasians. Hispanics did not show significant differences from any other group in this study, in mean preference ratings for any of the three environment types depicted. Four perceptual dimensions were found in the mountain category. These were labelled (1) Partially Screened Views, (2) Rock Formations, (3) Enclosed Views, and (4) Exposed Rocks. In the grassland category, there were only two perceptual dimensions - (1) Pathways and (2) Buttes/ Escarpments. Some significant group differences were noted among these dimensions. In utilizing the Kaplans' Informational Processing Model of Environmental Preference, it was found that Complexity and Mystery correlated highly with the landscape preferences of all groups. A multiple regression analysis of the predictors found that they have significant effects on the preferences of all groups and predicted the preferences of all groups, except for Blacks, in similar manner.
Open Access
A guide for small-scale organic vegetable farmers in the Rocky Mountain region
(Colorado State University. Libraries, 2009) Stonaker, Frank, author; Stushnoff, Cecil, advisor; Davis, Jessica, advisor; Cranshaw, Whitley, advisor
The steady growth over the last twenty-five years in the organic agriculture sector has been paralleled by growth in the number of farmers' markets and community-supported agriculture (CSA) operations, reflecting increased consumer interest in "buying locally". Small organic farms represent the core of the local growers involved and invested in this trend in Colorado and yet have had little research to direct or support their forays into organic agriculture. Agricultural research focusing on organic systems and the challenges in soil fertility management, pest and disease management, and plant breeding appropriate for organic production has lagged. The research in organic production that has been done in the US has occurred largely on the east and west coasts and upper Midwest where climatic conditions are different from that of the arid, inter-mountain west. In 2002 the Horticulture and Landscape Architecture Department at Colorado State University initiated the Specialty Crops Program, and soon after the Rocky Mountain Small Organic Farm Project (RMSOFP) was established to address issues relevant to small-scale organic farmers in Colorado and the region. Within this context a prototypic small organic farm was developed on certified organic land at the Horticulture Field Research Center (HFRC) neat Ft. Collins, Colorado. A variety of research projects have been undertaken ranging from cultivar trials of vegetables, to evaluations of phytochemicals of vegetables grown on organic and conventional plots. This production guide for small-scale organic farmers provides a basis for future research, education, and outreach efforts that can be made available to farmers, extension workers, teachers and students. It is a comprehensive production guide for small-scale organic farmers in the climatic zones similar to those found in Colorado. Topics included are: soil fertility management, tillage, irrigation, and pest management. Detailed production recommendations for melons, tomatoes, spinach and lettuce are presented, with cultivar trial results of melons, tomatoes and spinach. Fifteen organic vegetable farmers from Colorado were interviewed about their production practices, and their comments are included.
Open Access
Addressing the threat of frost damage on peach floral buds through large-scale cold hardiness phenotyping, dynamic weather modeling and non-targeted metabolomic and proteomic analysis
(Colorado State University. Libraries, 2023) Sterle, David, author; Minas, Ioannis, advisor; Sharp, Julia, committee member; Prenni, Jessica, committee member; Caspari, Horst, committee member
Cold damage to reproductive tissues is the greatest threat to the profitability of peach (Prunus persica) growers worldwide. Cold hardiness is the extent to which peach floral buds super-freeze without suffering lethal damage. Although no changes are visible externally to floral buds for much of the dormant season, cold hardiness fluctuates as they acclimate, deacclimate and respond to abiotic stressors such as temperature or drought. A greater understanding of the mechanisms involved in these fluctuations involves accurate and frequent measurement of the extent to which cold hardiness is changing, and the ambient weather factors influencing the changes, at different stages of the dormant season. Warmer or more erratic temperature changes during the dormant season threatens peach floral buds to more frequently receive frost damage if cold hardiness becomes misaligned with the timing of lethally cold weather events. Statistical analysis of the trends and forces impacting the cold hardiness of floral buds can help identify significant patterns. These patterns can be used to better understand the physiological mechanisms affecting cold hardiness changes, and they can be used to help predict the impact of weather conditions on cold hardiness. In addition to their use in a practical sense by growers to aid in frost management decisions, accurate cold hardiness prediction models can be used to estimate what effects foreseeable climate effects can have on the outlook of future peach production. Metabolic changes are known to occur in dormant plants, although the effects of the metabolome in peaches on cold hardiness are unknown. Changes associated with cold hardiness likely follow several trends. One such trend is the fluctuations of metabolic abundances across the season, which are more associated with the endodormancy, and ecodormancy phases and the prebloom phase. These trends likely take place every dormant season as buds undergo a steady process of acclimating and deacclimating. Another trend is the response floral buds exhibit in response to acute cold events, in order to rapidly increase cold hardiness. The study of this response necessitates the monitoring of cold hardiness as well as the metabolic shift to the weather event. The response can be further elucidated by comparing cold hardiness and metabolic changes between genotypes that have different cold hardiness phenotypes. By exploring changes a cold hardy genotype undergoes, geneticists may be able to target certain metabolic expressions that may increase the frost tolerance of future cultivars. Since frost damage can be so destructive to peach production, it is necessary to understand the risks to the peach industry moving forward surrounding climate change, and it is also necessary to understand the extent to which frost tolerance can be improved in future cultivars. This study uses a multifaceted approach to cold hardiness which involves improved and large-scale cold hardiness phenotyping using differential thermal analysis, dynamic weather prediction models and associated metabolic regulation understanding.
Open Access
Air and medium temperatures for Alstroemeria 'Atlas' and 'Monika'
(Colorado State University. Libraries, 1987) Keil, Linda Sue, author; Goldsberry, Kenneth L., advisor; Hanan, Joe J., committee member; Ross, Cleon, committee member
Alstroemeria cultivars 'Atlas' and 'Monika' were grown in four 25.4 m2 fiberglass-covered greenhouse compartments at the W.D. Holley Plant Environmental Research Center, Colorado State University. Each compartment contained two raised redwood benches subdivided into four 75 x 105 cm plots with buffer zones at either end of the bench, Individual benches had replicated plots of cooled and noncooled substrate treatments. The cooled plots contained seven loops of .625 cm OD Biotherm tubing buried 15 cm beneath the pea gravel surface. A thermostatically-controlled cooling system supplied cold water, upon demand, in an attempt to maintain a medium temperature of 11°C. Compartments were heated to 10° to 11°C during night periods, and the following daytime temperature regimes were established: Compartment A, 14° to 20°C; Compartment B, 20° to 26°C; Compartment C, 23° to 28°C; and Compartment D, 17° to 23°C. A night break was provided with incandescent lamps when natural daylengths were less than 12 hours. Developing cultivar rhizomes were transferred from 10 cm pots to the bench plots on November 18, 1985. The first flower data were taken on February 10, 1986, then collected every other day and summarized weekly during the next 52 weeks. Parameters measured included: stem length, flower grade, and total production. Data were analyzed as a split-split plot design with media treatments randomized within each pair of plots. Total flower production of 'Atlas' in all compartments was 1.6 times as great as 'Monika'. Significantly larger numbers of flower stems were produced in the cooled substrate of compartments A and D. The results provided evidence that the greatest production of 'Atlas' and 'Monika' occurred with average daytime temperatures of 20°C combined with an average medium temperature of 12°C to 14°C. Consequently, the cooled medium treatment coupled with cooler air temperatures allowed production to continue virtually year-round. The warmer daytime temperatures of compartments B and C increased the flower quality. However, the higher production in compartments A and D far outweighed the advantage that warmer temperatures contributed to quality. The flower quality of 'Monika' was considerably less than that of 'Atlas' in all temperature treatments. Warmer daytime temperatures also contributed to longer stems. 'Atlas' and 'Monika' stems from compartment C averaged a maximum of 13 cm longer than those from the remaining compartments. 'Atlas' stems were significantly longer than those of 'Monika' in all compartments. A five week sub-trial was conducted to determine air temperature effects on Alstroemeria inflorescence characteristics. Parameters measured included: number of cymes per stem, cyme length, stem thickness, and number of buds per cyme. Data were analyzed as a split plot design. No significant differences were observed for number of cymes per stem and stem thickness between compartments, although 'Atlas' had thicker stems than 'Monika'. A significant trend toward increasing cyme length with increasing daytime temperature was evident in both cultivars. Significantly more buds were produced on stems of both cultivars in compartment D (i.e., 20°C average day air temperature) compared to all other compartments.
Open Access
An analysis of the physiology and environmental interactions that influence species-specific transpiration estimates
(Colorado State University. Libraries, 2014) Barnard, David Michael, author; Bauerle, William L., advisor; Binkley, Daniel, committee member; Chávez, José L., committee member; Martin, Patrick H., committee member
To view the abstract, please see the full text of the document.
Open Access
An evaluation of yield and quality characteristics for vegetable crops grown under organic management in Fort Collins, Colorado
(Colorado State University. Libraries, 2020) Mason, Tyler, author; Uchanski, Mark, advisor; Bartolo, Michael, committee member; Johnson, Sarah, committee member; Prenni, Jessica, committee member
To view the abstract, please see the full text of the document.
Open Access
An overview of the Fort Collins park system emphasizing City Park as it relates to the development of the community
(Colorado State University. Libraries, 1996) Tunner, Carol, author; Held, R. Burnell, advisor; Aukerman, Robert, committee member; Leyendecker, Liston E., committee member
Through an overview of the history of the early park system of Fort Collins, Colorado, it is shown that City Park has been a cohesive stimulus over the years in helping to define and maintain the character of the growing city. What happened in the past becomes the segue to the present, and ultimately to the future. In order to preserve this family oriented community character and maintain a healthy balance for its citizens, the historical character of City Park should be the basis for its restoration and preservation. A city out of balance demolishes or sacrifices its past for its present with no thought of its future.....the best of the past is irreplaceable.
Open Access
Analysis of root growth in two turfgrass species with minirhizotron and soil coring methods
(Colorado State University. Libraries, 2015) Young, Jason Scott, author; Qian, Yaling, advisor; Comas, Louise, advisor; Ocheltree, Troy, committee member
In this study root growth of a turf-type variety of inland saltgrass (Distichlis spicata L. Greene) (a native grass with varieties in development by Colorado State University) and Kentucky bluegrass (Poa pratensis L.) (a common turfgrass planted in the arid and semi-arid west) was examined under saline conditions in a pot experiment and non-saline conditions in the field. Since turfgrass is a high user of water, the turf industry is interested in using native species that use less water and also salt-tolerant species, which may allow the industry to use marginal water (grey water) for irrigation. However, plants with different root distributions will need to have irrigation managed differently. These experiments examined root growth differences in saltgrass and Kentucky bluegrass to begin exploring how these species might need to be managed differently in saline and non-saline conditions. Two separate experiments were conducted to answer the two objectives of this research: (I) to evaluate root growth of inland saltgrass under saline conditions in a growth chamber and (II) observe unrestricted root growth in the field both over time with a minirhizotron camera system, and in stands of differing age with a soil coring method. In the first experiment, root growth in container grown saltgrass under salt stress showed increased flushes of fine root growth in response to moderate levels of salinity (8 dS/m) compared to the control. Root growth increased about 3 weeks after salt treatments began, suggesting that this time frame was long enough for ionic stress to occur in the shoots root responses were seen. In-growth root tubes placed in the soil of the salt stressed saltgrass showed trends of increasing root and rhizome growth with increasing salt stress, this was opposite the trends seen in Kentucky bluegrass. In experiment II, field-grown saltgrass plots of varying stand age (1, 4, 5, and 8 years) had less root biomass in soil layers less than 30 cm compared to bluegrass. Kentucky bluegrass root biomass was nearly zero below 30 cm, whereas saltgrass had roots down to 275 cm in stands that had been growing longer than 4 years. In soil layers up to 1.8 m, saltgrass root mass was greater with increasing stand age. Minirhizotron observations showed that 15°C was the soil temperature at which root growth began in saltgrass and dramatically slowed in Kentucky bluegrass which had a growth range of 0 to 15°C. When soil temperatures were above 15°C saltgrass roots continued to grow at a slow but steady rate during the summer months. Findings that saltgrass produced roots deeper in the soil profile and was responsive to saline soil may impact where and when it is used. If stored moisture is present deep within the soil, saltgrass has a unique ability to mine this water that would be out of reach of shallower rooted turfgrasses. Deep rooting can also have implications for slope stabilization which can be important in the arid west where bare slopes can be stripped of soil during heavy and infrequent rainstorms. The responsiveness of rooting in saline soils may be the underlying mechanism explaining the enhanced growth of saltgrass under mild saline conditions. Increased surface area from new fine root production can enhance root water uptake providing more water to growing shoots. More studies are needed to explore root responsiveness in many types of plants, including saltgrass, to discover the true benefit of fluctuations in root system architecture.
Open Access
Antioxidant properties of date palm (Phoenix dactylifera L.) cultivars
(Colorado State University. Libraries, 2008) Al-Turki, Saleh Mobarak, author; Stushnoff, Cecil, advisor
The fruit and pits of date palm (Phoenix dactylifera L.) cultivars from the United States (US) and Saudi Arabia (SA) were analyzed for their total phenolic contents and antioxidant activity for two years. The amount of total phenolic compounds and antioxidant activity in all date fruit and pit cultivars tested in this study, at the Tamar stage, were significantly different. Total phenolic contents of fruit ranged from 507.03 (Gur SA) to 225.02 (Medjool US) mg Gallic Acid Equivalents (GAE)/100g FW and antioxidant activities ranged from 1400.14 to 228.06 μmole TEAC/100g of fresh weight (ABTS) in Deglet Noor US and Khalasa US respectively. DPPH of fruit ranged from 117.75 to 165.42 μmole TEAC/100g of fresh weight in Deglet Noor (US) and Khalasa (US) respectively. The pit, which is about 12% of date fruit weight, ranged from 66.68 (Hilali US) to 14.51 (Amir Hajj US) mg GAE/g DW total phenolics. ABTS ranged from 679.01 to 45.83 µmole TEAC/1g of dry weight in Hilali US and Hayany (US) respectively. DPPH ranged from 15.94 to 3.92 μmole TEAC/g of dry weight in Sukari (SA) and Khalasa (SA) respectively. A significant association between the total phenolic content and antioxidant activities was found in both years with ABTS and DPPH. Moreover, there was a strong relationship between measurement of antioxidant capacity by ABTS and DPPH in both years in fruit and pits. Fruit of one cultivar, Khalasa, was available both years from the (US) and (SA). Phenolic content, ABTS and DPPH radical scavenging capacity of fruit and pits differed in their antioxidant activity due to different location and other environmental factors. Fruit or pit (SA) cultivar was significantly higher than the (US) cultivar over all treatments. Deglet Noor (US) fruit which makes up about 90% of California's date crop was found to be the best over all cultivars of those tested in this study. Hilali (US) was the best antioxidant source of date pit cultivars in (US), whereas, Sukari (SA) was the best antioxidant source of pits in (SA). Thus, this research demonstrates the potential of date fruit and pits as antioxidant functional food ingredients.
Open Access
Asexual propagation of blackbrush (Coleogyne ramosissima Torr.)
(Colorado State University. Libraries, 1990) Weglinski, Eugene, author; Hughes, Harrison G., advisor; Redente, Edward F., committee member; Orr, Greg L., committee member
Mining disturbances in Canyonlands National Park occur, in part, in monotypic stands of blackbrush (Coleogyne ramosissima Torr.). Blackbrush does not readily reseed itself following disturbance, therefore, stem cuttings and mound layering were evaluated as methods for asexual propagation as a means of providing plants to be used in a revegetation program. Rooted cuttings were planted to evaluate their use in revegetation. Rooting of stem cuttings was evaluated using talc, 0.3% (w/v) indole-3-butyric acid (IBA), 0.8% (w/v) IBA, and Rootone, a commercially available rooting hormone mixture. Treatments were applied to cuttings collected from new, one-year-old, and older wood (2+ years) at three separate dates. Propagation by stem cutting proved successful with highest rooting percentages achieved using current year's growth with application of supplemental rooting hormone. Differences between hormone treatments were insignificant. However, differences were found in comparisons between hormone treatments and a talc control. Mound layering was investigated with 20 plants at each of three sites and involved removal of all growth over 2.5 cm above ground level. Supplemental water was applied to half the plants for the duration of the study. Plants were buried to one-half of the height of new growth on a monthly basis. Plants responded to the treatment with a flush of growth but did not root. Thirty-eight cuttings rooted the prior year were planted in spring 1989 in an abandoned roadbed to evaluate field establishment. Treatments included application of supplemental water at two week intervals. Results were inconclusive.
Open Access
Assessment of methods to screen for carotenoids in yellow-fleshed potato germplasm
(Colorado State University. Libraries, 2020) Logrono, Jeremy Brandon, author; Holm, David G., advisor; Jayanty, Sastry, advisor; Heuberger, Adam, committee member; Byrne, Patrick, committee member
Rapid Evaporative Ionization Mass Spectrometry (REIMS) has the capability to rapidly perform tissue analysis without sample preparation, extractions or chromatography required. The study was conducted to evaluate REIMS as an efficient platform to identify carotenoids in yellow-fleshed potato germplasm (N = 60) from the Colorado Potato Breeding and Selection Program. The specific aim eventually is to improve selection efficiency and accelerate genetic gain in nutritional quality of potato cultivars. Phenotypic tuber flesh color (FC) rating (0 – 3), chroma values, and individual and total carotenoids data were collected, processed and combined with multivariate analyses to help in REIMS data interpretation. Results showed that orange-fleshed (FC 3) potato genotypes gave significantly higher overall carotenoid content (P <0.0001) compared to the white-fleshed (FC 0), yellow-fleshed (FC 1) and dark yellow-fleshed (FC 2) genotypes. Zeaxanthin was the major carotenoid detected among the 60 selections/cultivars evaluated. The association between tuber flesh chroma and carotenoid content was analyzed. Results from Pearson correlation analysis revealed positive correlations overall. The correlation coefficient values (r) for lutein vs. chroma (r = 0.56, P < 0.01), zeaxanthin vs. chroma (r = 0.60, P < 0.01) and total carotenoid vs. chroma (r = 0.63, P < 0.01) were considered moderate. A metabolite mass fingerprint for each replicated sample was collected via REIMS to build a data matrix and processed to test the fit with prediction models. Multivariate methods of analysis (MVA) of principal component analysis (PCA), partial least square (PLS) and orthogonal-PLS (OPLS) were created to determine any sample differentiation among the yellow germplasm. FC rating data (0 – 3) were integrated to MVA models as a covariate. Rep 3 samples were excluded in all MVA analyses due to high presence of noise in the raw data. PCA of Reps 1 and 2 (n = 95) showed a predictive power of 48.4% (Q2). No apparent trends or separations based on flesh color was observed in the PCA model. PLS and OPLS supervised models illustrated better differentiation among sample components. OPLS model (n = 71) of high carotenoids (FC 3) vs. low carotenoids (FC 1 & 0) with a predictive power of 56.1% (Q2) was considered the best model due to clear separations of high vs. low carotenoid samples. Loadings and variable importance score (VIP) data were also analyzed to rank metabolite masses that contributed to differentiation of samples, detecting mostly lipid class molecules. Precursor molecules of lutein and zeaxanthin were not detected from the REIMS analyses and carotenoid fragmentation products were most likely contributing to differentiation among samples. Further research is needed to verify identification of carotenoid fragmentation in REIMS as well as the use of more portable and cost-efficient devices.
Open Access
Bacteriomes of peaches and cover crops
(Colorado State University. Libraries, 2024) Newberger, Derek R., author; Vivanco, Jorge M., advisor; Minas, Ioannis, advisor; Paschke, Mark, committee member; Manter, Daniel, committee member
Replant syndrome (RS) of fruit and nut trees causes reduced tree vigor and crop productivity in orchard systems due to repeated plantings of closely related tree species. Although RS etiology has not been clearly defined, the causal agents are thought to be a complex of soil microorganisms combined with abiotic factors and susceptible tree genetics. Different soil disinfection techniques alleviate RS symptoms by reducing the loads of the deleterious microbiome; however, the positive effect on crop growth is temporary. Here, the current understanding of RS in orchards from a soil microbiome perspective is reviewed. The resolution to RS will require experts to outline explicit descriptions for its symptoms, determine its etiology, identify the primary phytopathogens, and fully explore sustainable treatments which alleviate RS. Two sustainable treatments of RS were selected to explore at a deeper level, soil disinfection and increasing crop diversity to observe what technique could help establish a healthy soil bacteriome. In a greenhouse study, soil disinfection via autoclave was then followed by cover cropping. It was found that soil disinfection increases plant biomass as compared to the control for only the first crop cycle while non-autoclaved soils with a history of cover cropping alleviated RS in RS-susceptible 'Lovell' peach seedlings. Although soil disinfection via autoclave was found to distinctly alter the peach soil bacteriome for the full duration of the study, this sustainable practice mimicking solarization failed to provide relief from RS for peach seedlings. Instead of long-term benefits, differential abundance comparisons displayed a loss of potentially beneficial bacteria due to soil disinfection. Paenibacillus castaneae and Bellilinea caldifistulae were beneficial bacterial species that uniquely colonized peach rhizosphere of non-autoclaved soils with a cover crop history. As a promising sustainable technique, a greater understanding of how inter-/intra-specific competition of cover crops can influence the bulk soil bacteriome was pursued. Alfalfa, brassica, and fescue were grown in 7 different plant combinations (1. alfalfa, 2. brassica, 3. fescue, 4. alfalfa-brassica, 5. alfalfa-fescue, 6. brassica-fescue, 7. alfalfa-brassica-fescue) across 3 density concentrations (low: 1–3 plants, medium: 24 plants, and high: 48 plants) for a greenhouse microcosm experiment. It was found that even in highly competitive conditions beneficial bacteria were enriched, however, there was an apparent trade-off where different plant combinations enriched distinct beneficial bacteria. As an example, even if a free-living nitrogen fixing bacteria such as an Azospirillum spp. was enriched in the bulk soil of alfalfa and brassica monocultures, it was not enriched in the bulk soil of an alfalfa-brassica plant mixture. Instead Pseudarthrobacter phenanthrenivorans, a phytohormone producer, was enriched in alfalfa-brassica plant mixtures. When zooming into the rhizosphere compartment of these microcosms, it was found that regardless of plant neighbor identity or density, a few rhizobacteria were highly correlated with a specific plant species. Meanwhile, certain plant species specific rhizobacteria were enriched only if specific conditions such as plant neighbor identity or density were met. Overall, our research found that growing diverse plant species plants prior to the re-establishment of a peach orchard could alleviate RS symptoms. Furthermore, cover crops can enrich different microbes when grown together as opposed to when grown separately. Lastly, although plants recruit a particular set of bacteria, this recruitment can shift depending on plant neighbor identity or density. Further study of cover crops may identify how they can alleviate RS in orchards worldwide.
Open Access
Benefits of using variable frequency drives on greenhouse exhaust systems
(Colorado State University. Libraries, 2012) Schreiner, Matthew, author; Newman, Steven, advisor; Qian, Yaling, committee member; Tisserat, Ned, committee member
Greenhouses provide many benefits to a plant producer by allowing for a tightly controlled environment best suited for the crop. Since sunlight is allowed almost free access to the inside of a greenhouse, removing heat buildup becomes a large obstacle to deal with. Energy needed to meet a typical cooling requirement can be costly and lowering overhead will be helpful to a sustainable greenhouse business. Variable frequency drive (VFD) technology has the potential to not only save electricity and reduce monthly operating costs, but can offer the grower climactic and water use benefits as well. Two greenhouses were compared for this study, one having a typical On/Off style fan system and the other has a VFD system installed. The parameters looked at were short cycling, total energy use, temperature, crop growth, and water use. The results of the research indicate that VFDs do offer significant reduction in electricity usage, showing only half of what the On/Off fans used. A reduction in water use was also seen with slightly greater crop growth in the VFD greenhouse. VFDs on exhaust fans show benefits that any greenhouse grower would like to have in their operation.
Open Access
Biocontrol of fusarium crown and root rot of fresh market tomato with trichoderma harzianum strains under greenhouse conditions
(Colorado State University. Libraries, 2003) Ozbay, Nusret, author; Newman, Steven E., advisor; Hanson, Linda E., committee member; Hughes, Harrison G., committee member; Wallner, Stephen J., committee member
Greenhouse tomato growers in the United States have few products available for chemical control of plant pathogens. Biological control of soilborne plant pathogens by antagonistic microorganisms is a potential alternative to the use of chemical pesticides during greenhouse production. Biological control experiments were conducted to test the effects of commercial and noncommercial strains of Trichoderma harzianum against Fusarium oxysporum f. sp. radicis-lycopersici on tomato plants grown in two different hydroponic media, coir and rockwool. This study also investigated effects of strains on growth of tomato seedlings under greenhouse conditions. Trichoderma harzianum is a fungus that attacks a range of economically important phytopathogenic fungi. Tomato (Lycopersicon esculentum Mill., cultivar Caruso) plants were inoculated with T. harzianum strains (PlantShield™, T22 and T95) prior to challenge with the pathogen. They were applied to growing media prior to sowing and to roots at transplanting at two inocula densities, 106 or 107 conidia/ml. The results of this study demonstrated that T. harzianum strains, especially applied at transplanting, decreased Fusarium crown and root rot incidence 79% for coir and 73% for rockwool, decreased disease severity 45% for coir and 48% for rockwool, and increased fruit yield 37% for coir and 25% for rockwool on tomato for control. The results also demonstrated that Trichoderma harzianum strains improved tomato seedling growth.
Open Access
Bridging the gap between biofortification and consumption: evaluating sorghum grain carotenoid degradation
(Colorado State University. Libraries, 2023) Lepard, Ariel, author; Rhodes, Davina, advisor; Van Buiten, Charlene, committee member; Prenni, Jessica, committee member; Scanlin, Laurie, committee member
Sorghum (Sorghum bicolor) is a major staple cereal crop consumed in sub-Saharan Africa and Southeast Asia, where some of the highest rates of vitamin A deficiency (VAD) are found. As with most cereals, sorghum has low concentrations of provitamin A carotenoids, which are converted to vitamin A in the body. Biofortification provides an opportunity to address VAD through the nutritional improvement of sorghum grain using a non-transgenic breeding approach to increase grain carotenoids. Though vitamin A biofortification in sorghum is possible, it is unknown if breeding for high carotenoids in the grain negatively affects carotenoid pathway functions in other tissues. Additionally, it is unknown if degradation during postharvest processing occurs to a significant degree in biofortified grain. To establish how breeding for high carotenoids in the grain affects the carotenoid pathway in other plant tissues, expression of ten genes in the carotenoid precursor, biosynthesis, or degradation pathways were evaluated in the grain, leaf, and root tissues. A correlation in the gene expression within the plant tissue, but not between the plant tissues, was found for most genes, which suggests that several of the carotenoid precursor, biosynthesis, and degradation genes are controlled by tissue-specific regulation. Correlation of carotenoid concentrations and gene expression was also found to be tissue specific, which further suggests tissue-specific regulation. The selection of genes with tissue-specific regulation for marker-assisted breeding reduces the chances of grain biofortification negatively affecting other tissues. Once carotenoids have been increased in the grain, it must be noted that vitamin A is not stable in most storage, processing, and cooking environments due to oxidative stress from light, heat, and oxygen. The degradation of the nutritional quality through post-harvest processing was evaluated by sampling carotenoid grain throughout harvest, drying, storage, processing, and cooking. Individual processing steps did not cause significant degradation but added up to significant degradation by the final cooking step, with ~39% of β-carotene loss. No significant difference between the loss in the different storage temperatures or cooking styles was seen. An increase in the target value from 4 μg β-carotene/g of sorghum to 5.6 μg/g will be needed to account for processing loss in order to provide 50% of the estimated average requirement (EAR) of vitamin A. Overall, both the information on tissue specific gene expression, and post-harvest degradation will further advance the development of carotenoid biofortified sorghum lines.
Open 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.
Open Access
Changes in golf course fairway soils under effluent water irrigation
(Colorado State University. Libraries, 2010) Skiles, David John, author; Qian, Yaling, advisor; Andales, Allan A., committee member; Koski, Tony, committee member
As the use of effluent irrigation increases, salinity and sodicity issues associated with its use continue to be of great concern to the golf course industry. The purpose of our research was to (i) observe salinity accumulation patterns on 4 fairways of two effluent water irrigated golf courses using 2 different types of sensors and to (ii) determine long-term changes in soil chemistry in soils under effluent water irrigation on golf course fairways. Temporal and spatial accumulation patterns were measured using a network of in-situ soil sensors located at two depths 15 and 30 cm for 5TE sensors and 8 and 19cm for Turf Guard sensors (TG2). Sensors measured electrical conductivity (EC), volumetric soil water content (SWC), and soil temperature data were collected continuously during the 2008 and 2009 growing seasons. Correlation was observed between 5TE sensor-measured soil salinity vs. saturated paste extracted soil salinity (r = 0.77). A significant exponential relationship was observed between TG2 sensor-measured soil salinity vs. saturated paste extracted soil salinity (R² = 0.97). In-ground measurements indicated that salinity can vary widely across a seemingly homogenous golf course fairway in a manner reflective of the underlying soil physical characteristics. Plots exhibiting low and high salinities presented opposite seasonal trends at Heritage Golf Course. Strong correlation was observed between average soil salinity and mean soil water content (r =0.76), soil salinity and the percentage of sand in the soil texture composition (r = -0.63) for Heritage fairway 1. High salinity was found on fairway 19 at Common Ground Golf Course. However, the salinity level as high as 10.6 dS/m is not a result of water reuse, but a historical geological contribution. Drainage appears to be vital in maintaining low soil salinity levels under effluent irrigation in clay soils. Slow to infiltrate, percolate and difficult to leach; predominately clay soils irrigated with effluent water can accumulate soil salinity over time. Our data suggested that a robust drainage network in predominantly clay soils irrigated with effluent could better manage salinity accumulation associated with poor drainage. To determine long-term changes in soil chemistry in soils under effluent water irrigation on golf course fairways, soil testing data was provided by the superintendent for the years of 1999, 2000, 2002, 2003, and 2009 for Heritage Golf Course in Westminster, Colorado. Soil samples were tested by Brookside Laboratories, Inc, New Knoxville, OH. Parameters of each soil sample tested included pH, extractable salt content (calcium, magnesium, potassium, sodium, iron, manganese, copper, zinc, phosphorus, and boron), base saturation percent of calcium, magnesium, potassium and sodium, soil organic matter (SOM), and cation exchange capacity (CEC). Regression analysis was used to evaluate the changes in individual soil parameters over time after the use of effluent water for irrigation. Soil pH, CEC, extractable aluminum, copper, manganese and iron along with both base saturation percentages and exchangeable percentages of calcium and magnesium did not change over time. The strongest indications of change are seen for extractable boron (R² = 0.56), Bray II extracted phosphate (R² = 0.56), and sodium base saturation percentage (R² = 0.44). The regression analysis indicated that B, P, and sodium increased linearly during the 8 year's irrigation with effluent water. Further studies are needed to determine if these parameters would continue to increase or would stabilize. Continued accumulation of sodium could eventually result in loss of soil structure.
Open 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.
Open 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.