Browsing by Author "Stushnoff, Cecil, advisor"
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Item 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, advisorThe 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.Item Open Access Antioxidant properties of date palm (Phoenix dactylifera L.) cultivars(Colorado State University. Libraries, 2008) Al-Turki, Saleh Mobarak, author; Stushnoff, Cecil, advisorThe 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.Item Open Access Comparative analysis of antioxidant properties, quality attributes and yield of organically and conventionally grown melons (Cucumis melo L.) and tomatoes (Solanum lycopersicum L.)(Colorado State University. Libraries, 2008) Salandanan, Karen A., author; Stushnoff, Cecil, advisor; Bunning, Marisa, committee member; Wallner, Stephen J., committee memberFresh fruits and vegetables including melons and tomatoes have gained considerable prominence in the American diet due to increasing awareness of their potential health and nutrition benefits. Consumers are starting to take a closer look not only at organoleptic qualities but also at nutritional value of the produce. This new trend of consumer preference for healthier food choices is one of the driving forces of the organic industry. Organically grown fruits and vegetables are perceived to be more nutritious than those that are produced under conventional production system. Comparison studies on selected fruit and vegetable crops have been carried out to examine this claim. However, verifiable results from well-designed experiments were very limited in many crops, including tomatoes and melons. This research assessed the difference in the antioxidant properties, quality attributes, and yield of organically and conventionally grown tomatoes and melons. Nutritionally superior cultivars were also identified which could be beneficial for small and medium sized farmers. Ten commercial cultivars of tomatoes were grown in 2005 and 2006, under certified organic and conventional production systems at the Horticulture Field Research Center, Colorado State University, Colorado USA. Melon and tomato cultivars were analyzed for their ascorbic acid, total phenolic content, Trolox equivalent antioxidant capacity (TEAC), percent dry matter, soluble solids content, and yield. A 3 to 6 fold difference in ascorbic acid, total phenolic content, and antioxidant activity was observed both in melon and tomato cultivars. Melons grown organically had significantly higher ascorbic acid when both years were combined while total phenolic content was significant only in the first year. In tomatoes, higher antioxidant activity was observed in organically grown tomatoes while yield and soluble solids concentration was higher under the conventional production system. Lower yield was observed in melon and tomato cultivars with higher antioxidant content and activity suggesting a possible trade- off between yield and nutrients. Compared to genotype, production system had less influence on antioxidant properties and fruit quality attributes. A significant interaction between cultivar and production system would likewise imply that some cultivars when grown organically or conventionally could have higher antioxidant content and activity. Thus, choice of cultivar was the most important contributor to high antioxidant properties. Based on the antioxidant index that we have developed as a tool to rank the cultivars in terms of antioxidant content and activity, the top melon cultivars, regard less of year or production system, are the following: 'Savor', 'Sweetie#6', 'Early Queen', 'Edonis' and 'Rayan'; while ' Jet Star', 'New Girl', 'Fanstastic', 'First Lady', and 'Celebrity' were determined to be nutritionally superior tomatoes. These nutritionally superior cultivars with high antioxidant levels may provide a competitive marketing and supply niche for small fam1 producers. Future initiatives could involve screening of tomato and melon cultivars for higher antioxidant content that could be utilized in breeding programs.Item Open 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, advisorTo view the abstract, please see the full text of the document.Item Open 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, advisorThree 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.Item Open Access Effects of organic, biological and conventional production methods on apple antioxidant levels, sensory qualities and human glycemic response(Colorado State University. Libraries, 2009) Bogs, Jana Dee, author; Stushnoff, Cecil, advisor; Wallner, Stephen, committee member; Bunning, Marisa, committee member; Kendall, Patricia A. (Patricia Ann), 1947-, committee memberDifferent cultivation systems of fruit trees may influence fruit nutrient and phytochemical content, and consequently, human responses. This experiment compared two cultivars of apples (Malus domestica Mill.) each under differing cultivation systems. These were evaluated for antioxidant activity, human glycemic response, soluble solids content, shelf life and consumer acceptability by human sensory panels. In addition, soil and leaf tissue tests were performed and correlated to the above results. 'Braeburn' (M. domestica) apples grown in Washington state under biologically-enhanced organic and conventional methods were evaluated in 2007. Treatments were split to include apples from the outside and inside of the tree canopies. There were no differences (P > 0.05) in ABTS or DPPH antioxidant activity between organic and conventional 'Braeburn' apples. Organic 'Braeburn' apples had a higher level (P = 0.003) of total phenolics (TP) than the conventional apples. Outside-canopy apples had higher TP, ABTS and DPPH antioxidant activity levels (P < 0.01) than inside-canopy apples. Organically-grown 'Braeburn' apples from both outside and inside the canopies had higher soluble solids levels (P < 0.001) than those conventionally-grown. Fruit soluble solids content was higher (P = 0.002) in 'Braeburn' apples from outside the canopies than from inside the canopies. There was no difference in shelf life between organic and conventional ‘Braeburn’ apples (P = 0.366), nor between outside-canopy and inside-canopy apples (P = 0.286). The 'Braeburn' overall acceptability sensory ratings for organic apples were significantly higher (P < 0.001), than conventional fruits, and outside-canopy fruits surpassed inside-canopy fruits (P < 0.001). 'Crimson Gala' (M. domestica) apples from Washington state orchards grown under biologically-enhanced conventional management and typical conventional management were evaluated in 2008. The biological apples had higher ABTS antioxidant activity than the conventional (P = 0.0498). The conventional 'Gala' apples had higher DPPH antioxidant activity (P = 0.002) than the biological. There was no difference (P = 0.681) between the biological and conventional 'Gala' apple total phenolics (TP) levels. None of the values used to compare human glycemic response were statistically different (P > 0.05). The conventionally-grown 'Gala' apples had higher soluble solids levels (P = 0.005), greater shelf life (P = 0.035), and a higher overall sensory rating (P = 0.014) than the biologically-grown fruit. The above measured values were also correlated with soil, leaf, and fruit tissue values. It should be noted that the biological 'Gala' orchard had a soil with a cation exchange capacity (CEC) of 7.1 meq/100g compared to the conventional control orchard's CEC of 11.3 meq/100g, which may have negatively affected the quality of the biological apples. Understanding how cultivation practices affect consumer acceptance will encourage growers to further improve production practices.Item Open Access Evaluation of antioxidant and sensory properties of selected cultivars of Colorado-grown lettuce (Lactuca sativa L.)(Colorado State University. Libraries, 2007) Bunning, Marisa, author; Kendall, Patricia, advisor; Stushnoff, Cecil, advisorEpidemiological evidence has substantiated the health benefits associated with the consumption of vegetables, particularly leafy greens. Lettuce (Lactuca sativa L.) cultivars (varieties) have usually been selected based on shelf-life, transportability, and yield rather than nutritional or sensory traits. Information on the effects of seasonality and genetics on various characteristics of lettuce is limited. Nutritional, antioxidant, and sensory profiles of lettuce may vary considerably among cultivars and in response to environmental factors that may fluctuate widely throughout the growing season. Bitterness, an important flavor characteristic of lettuce, is generally thought to increase with higher growing season temperatures and may vary with phenolic content.Item Open Access Inhibition of HT-29 colon cancer cell cultures by extracts from biodiverse germplasm sources of Solanum tuberosum L.(Colorado State University. Libraries, 2012) Zuber, Tatiana, author; Stushnoff, Cecil, advisor; Holm, David G., committee member; Byrne, Patrick F., committee member; Thompson, Henry J., committee memberTo view the abstract, please see the full text of the document.Item Open Access Overexpression of mannitol-1-phosphate dehydrogenase increases mannitol production and confers salt and chilling tolerance in transgenic petunia cv. Mitchell(Colorado State University. Libraries, 2000) Jiang, Yu-Jen, author; Stushnoff, Cecil, advisor; Hughes, Harrison G., committee member; Ishimaru, Carol, committee member; Wallner, Stephen J., committee memberDiploid petunia plants (Petunia hybrid, cv. Mitchell) transformed with a bacterial gene (mt/ D) encoding mannitol-1-phosphate dehydrogenase enzyme (MTL D), resulting in high mannitol expression, were developed and studied in this research. Transgenic lines and wild type control plants were exposed to salinity and chilling stress with the express goal of delineating the impact of manniol on these abiotic stresses. Phenotypically, there was no difference in growth between in vivo wild type and transgenic lines under non-stress conditions. However, transgenic lines expressing high mannitol levels were found to exhibit a greater capacity to tolerate salinity and chilling stresses compared to wild type and transgenic lines expressing low mannitol levels. Enhanced salinity tolerance was observed in seed germination (T2 generation), and in vegetative growth and floral development of transgenic lines expressing high mannitol levels. Also, based upon foliage symptoms and membrane leakage, transgenic lines expressing high mannitol levels were more tolerant of chilling stress compared to with wild type and transgenic lines expressing low mannitol levels. Carbohydrate analysis of wild type and transgenic plants showed that mannitol was the single carbohydrate most affected by plant lines. Two transgenic lines (M3 and M8) always had higher mannitol expression levels when compared to wild type and the other two transgenic lines (M2 and M9) under non-stress and stress conditions. Therefore, the function of high mannitol expression should be considered in developing improved tolerance of petunia plants to salinity and chilling stresses. However, assuming 90 % water content in leaf tissue, leaf osmotic potential of high mannitol expressing lines contributed by mannitol accounted for only 0.006 %-0.01 % of increased osmoregulation caused by salinity stress, and 0.04 %-0.06 % of the increase in osmotic potential caused by chilling stress, respectively. Quantitatively, mannitol appears not to play a role as an osmoregulator in osmotic adjustment in response to both salinity and chilling stresses. Rather, the data from this research suggest that mannitol may function as an important osmoprotectant in enhancing salt and chilling tolerance of those transgenic petunia lines expressing high mannitol levels.Item Open Access Physiological responses of grapevines to environmental stresses(Colorado State University. Libraries, 1997) Dami, Imed Eddine, author; Stushnoff, Cecil, advisor; Smith, Danny, committee member; Morgan, Jack, committee member; Hughes, Harrison, committee memberThe field response of several grapevine (Vitis vinifera L) cultivars, grown at the Orchard Mesa Research Center, to methanol application on foliage and trunks was investigated. Sublethal methanol doses were determined as 90% for leaves and 100% for trunks. The application of these concentrations on grapevines during mid-summer did not affect sugar accumulation, photosynthesis, transpiration, stomatal resistance, yield components, nor bud cold hardiness as compared to untreated vines. Cold hardiness and endogenous levels of soluble sugars were monitored during the dormant season for Chardonnay and Riesling dormant buds and stem cortical tissues. Endogenous levels of glucose, fructose, raffinose, stachyose, but not sucrose were strongly associated with cold hardening, increasing from the onset of cold acclimation in August to maximum cold hardiness in December and January. During dehardening in March and April, levels of these sugars dropped as temperature increased. A high ratio of glucose and fructose to sucrose coincided with maximum cold hardiness, and a low ratio was associated with the dehardened condition in fall and spring. Neither cold hardiness nor soluble sugars of grape tissues were influenced by late harvest compared to harvest at normal fruit maturity. Various alginate- and sucrose-based cryoprotective treatments were tested under laboratory and field conditions for their capacity to increase freezing resistance by slowing deacclimation and delaying bud break of dormant grapevines. Early application of the treatments in mid-winter did not have a significant effect on cold hardiness of buds nor canes. However, over three years late winter and early spring field applications consistently increased freezing resistance of treated primary bud and cane tissues by up to SC and 7C, respectively, as compared to untreated grapevines. Under laboratory conditions, the bud break of treated cuttings was delayed by at least 4 phenological stages when compared to the control. In the spring, similar treatments were applied on ecodormant grapevines. Visual evaluations, on a weekly basis, resulted in bud break delay of several days (up to 10 days) of the treated vines as compared to the control. At harvest, the yield components and fruit composition were not affected in treated vines. These findings appear promising to reduce injury in viticultural areas where spring frost is a threat.Item Open Access Response of 'Red Lake' currant and Red-osier dogwood to cold acclimation(Colorado State University. Libraries, 1995) Hanna, Mark David, author; Stushnoff, Cecil, advisor; Klett, James E., committee member; McNeil, Michael, committee memberTwigs of 'Red Lake' currant (Ribes rubrum L.) and Red-osier dogwood (Cornus sericea L.) were collected at the beginning of each month starting October 1992, and ending the first of April 1993. Twig samples were subjected to controlled temperature treatments: 0°C, 10°C, -5°C, 0°C for 12 hr/ 10°C for 12 hr, and -5°C for 12 hr/ 10°C for 12 hr for one month. Treated and field samples were evaluated for hardiness by freeze tests and glucose, sucrose, raffinose and stachyose content in cortical tissue. A study of hardiness was repeated the following year beginning in September and ending the first of April. Cold tolerance was promoted best by fluctuating temperatures in the fall with greater acclimation achieved in the colder temperature treatments as the season progressed until mid-winter and into the spring months when de-acclimation occurred. Hardiness was best retained by the cooler steady temperatures. The endogenous content of raffinose was strongly associated with cold hardiness in both plant materials. Raffinose and glucose levels of field samples from both currant and dogwood were significantly correlated with cold hardiness. Stachyose was also associated with hardiness of currant taken from outdoors and treated at 0°C. Sucrose was associated with hardiness in dogwood stored at -5°C/10°C. The best association between sugars and cold tolerance in either plant species was seen in samples taken directly from the field with no treatment. Storage at 0°C/10°C increased raffinose as hardiness increased in both species. Storage at 0°C and at -5°C increased raffinose as hardiness increased in dogwood. but not in currant. Warm temperature storage as 10°C and -5°/10°C destroyed the relationship between hardiness and raffinose levels in both plant materials.