Department: Horticulture and Crop Science ![[clear]](close-x.png "Remove this limiter")
92 matches in the database.
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1.
Acuna, Alejandra A.
DISSIPATION AND EFFICACY OF PENDIMENTHALIN, PRODIAMINE, DITHIOPYR AND BENSULIDE AS AFFECTED BY DOSE AND APPLICATION TIMING FOR CRABGRASS (DIGITARIA SP) CONTROL IN A TURFGRASS ENVIRONMENT.
Degree: PhD, Horticulture and Crop Science, 2009, Ohio State University
► The dissipation of herbicides in a turfgrass environment is important to determine…
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▼ The dissipation of herbicides in a turfgrass environment is important to determine potential water and soil contamination and verify the actual herbicide concentration in the soil to assure long term weed control. Knowledge of herbicide dissipation and the effect of dose and application timing on weed control would help turf managers to better understand herbicide dynamics, and as a result schedule their herbicide application to improve weed control in the turf environment. Pendimethalin ( N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidine), Prodiamine (1,3-Benzenediamine, 2,6-dinitro-N1,N1- dipropyl-4-(trifluoromethyl)), Bensulide [S-(O,O-diisopropyl phosphorodithioate) ester of N-(2-mercapto) benzenesulfonamide] and Dithiopyr [S,S-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate] were applied to a Kentucky bluegrass turf at 2288 ga.iha-1,737.08 g a.i. ha-1,11339.75 g a.i ha-1 and 421.88 g a.i ha-1,respectively,either once, twice (applications were separated 30 days) or using half of the cited doses twice (separated 30 days). All herbicides and doses were applied in autumn 2007 and again in spring 2008. The design of the experiment was completely randomized with three replicates per treatment. The whole experimental area was seeded with crabgrass (Digitaria sp) at 1.2 kg ha-1 before herbicide application. Soil temperature and moisture were measured during the experiment. Soil samples were taken from each individual plot: 0, 4, 8, 16, 32, 36, 40, 48, 64 and 128 days after initial treatment (DAT). Each soil sample was divided in three sections: verdure-thatch, 0 to 5 cm and 5 to 10 cm. Herbicide was extracted from each section and quantified using a gas chromatograph with a NPD detector, using benfluralin (N-butyl-N-ethyl-2, 6-dinitro-4-(trifluoromethyl) aniline) as the internal standard. Herbicide efficacy was measured every 15 days counting number of crabgrass plants per square meter starting on May 1, 2008 until September 30, 2008. More herbicide was detected in the verdure and thatch layer. The amount of herbicide detected in the soil at 32 DAT date of the second application, was not double of the dose applied. Herbicide dissipation was quicker in spring than in autumn, mainly due to differences in soil temperature and moisture. In Autumn, more herbicide was detected at the end of the study (128 DAT) compared to Spring. Differences in herbicide efficacy were detected at the end of the season (September 30, 2008), dithiopyr provided better crabgrass control was offered by regardless of season of application. No statistical differences in crabgrass count were detected due to herbicide dose. However, 0 crabgrass plants per m2 were observed when full followed by full recommended dose was applied. These studies indicated the influence of soil temperature and moisture on herbicide rate of dissipation and the effect of the turfgrass environment in decreasing reported herbicides half lives.
Advisors/Committee Members: Gardner, David.
Subjects: Agronomy
Keywords: turf,herbicide,dissipation
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2.
Amisi, Karen Janila.
Strategies for managing weeds in a wheat, red clover, vegetable crop rotation transitioning to organic production.
Degree: PhD, Horticulture and Crop Science, 2005, Ohio State University
► Weed management is one of the biggest challenges faced by organic farmers.…
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▼ Weed management is one of the biggest challenges faced by organic farmers. We investigated two weed control strategies critical period (CP) of competition and no seed threshold (NST), and the effect of soil amendments. Field experiments were conducted at the Ohio Agricultural Research and Development Center in Wooster, OH. In 2001, a 4-year rotation of wheat, clover, cabbage, and processing tomato was established in soil previously in a conventional corn/soybean/forage rotation. The experimental design was a split plot in a randomized complete block with 4 replications. Main plots were soil amendments (none, raw dairy manure, composted dairy manure). Amendments were applied in spring at the rate of 101 kg N/ha and incorporated prior to planting. Subplots were weed control strategies; NST, where seedling weeds were removed weekly and no weeds permitted to mature seeds, and CP, where plots were kept weed-free for the first 5 weeks of crop growth. Evaluations included emerged weed communities both in the field and seedbank. Time taken to hand-weed was documented and labor cost of using CP and NST weed management strategies calculated. Yield of tomato and cabbage were recorded. The NST reduced redroot pigweed (Amaranthus retroflexus L.) and commom lambsquarters (Chenopodium album L.) by 30 - 62% and 22 - 60% respectively. This was corroborated by weed seed data from soil samples taken the spring. Some significant effects (P < 0.05) were noted among the soil amendments on density of redroot pigweed and common lambsquarters, though no clear trends were observed. Achieving the NST required 33 to 92 % more labor than did the CP. However, the cost of labor required for the NST was not greater than weed control costs typically experienced by organic farmers. In a greenhouse experiment, growth and seed production of redroot pigweed was reduced in field soil amended with livestock manure. Growth and seed production of the weed was greater in soils amended with compost. Rates of manure and compost were equivalent to 2x and 3x those applied to tomato and cabbage in the field experiments.
Advisors/Committee Members: Doohan, Douglas J.
Subjects: Agriculture, Plant Culture
Keywords: Organic vegetables; Weed management; Weed Thresholds; Critical Period of Competition; Organic amendments
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3.
Andiru, Gladys Anguti.
EFFECTS OF CONTROLLED-RELEASE FERTILIZER ON NUTRIENT LEACHING AND GARDEN PERFORMANCE OF IMPATIENS WALLERIANA (HOOK. F. ‘XTREME SCARLET’).
Degree: MS, Horticulture and Crop Science, 2010, Ohio State University
► This thesis describes the effects of controlled-release fertilizers (CRF) of different formulations…
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▼ This thesis describes the effects of controlled-release fertilizers (CRF) of different formulations and longevities on nutrient leaching out of the containers and garden performance of Impatiens walleriana. In the first experiment, impatiens plants were grown with Osmocote Plus 16-9-12 formulation of 5-6 month (5-6M) and 8-9 month (8-9M) longevities placed at four positions in the container: Topdressed, Incorporated, Top-one-third and Bottom. A 150 mgL-1 N Peter’s Professional water-soluble fertilizer (WSF) of 20-10-20 formulation was used as a control. Leachates were collected at every irrigation and the concentrations of N, P, and Fe in the leachates were measured. Shoot dry weight (DW) and canopy cover (CC) were also measured. Total amount of water leached and nutrients lost from CRF and WSF were quantified. WSF produced plants of similar quality as CRF treatments except when CRF was applied at the bottom of the container. This fertilizer placement resulted in plants with the lowest DW, CC and leached the most P and Fe. CRF applied as topdressed leached the highest amount of N. Irrigating with a known volume of WSF solution leached less N and P but more Fe than 5-6M treatment. The WSF leached similar amount of nutrients as 8-9M CRF. In a second experiment with the same fertilizers, the amounts of water, N, P and Fe leached or lost out of the containers during irrigation with a hose were quantified. Irrigating plants with a hose caused up to 62% more water loss and up to 95% more nutrient loss during irrigation with WSF than CRF. In a third experiment, Osmocote Plus 15-9-12 of 3-4, 5-6, 8-9 and 12-14 month longevities were applied at rates of 1.4, 3.4, 6.8, 10.2 and 13.6 kgm-3. The same WSF as in the first experiment was used as a control. Impatiens plants were grown in the greenhouse and consumer evaluations were performed. Plant CC, flower cover (FC) and DW were determined. Commercially acceptable plant quality was achieved with CRF application rates between 3.4 - 6.8 kgm-3. The aesthetic value of plants was not affected by the differences in DW, FC or CC. In experiment four, the same treatments as in experiment 1 were used with the addition of a treatment of a 50 – 50% blend of 5-6M and 8-9M. Impatiens plants were grown in the greenhouse and transplanted in the field where no fertilizer was applied. DW, consumer ratings (CR) and leaf greenness (LG) were obtained. Plants grown with CRF performed better in the field than WSF grown plants. CRF treated plants were less chlorotic, had greater DW and CR in the field. Based on our study, the standard 8-9M longevity CRF at medium rates resulted in lower N, P and Fe losses, and plants with increased DW, high CC and FC. Further work with other species is necessary to validate the results obtained with impatiens. However, at least for impatiens and under our experimental conditions, standard 8-9M longevity CRF at medium rates seems to be the best option.
Advisors/Committee Members: Pasian, Claudios C.
Subjects: Agriculture
Keywords: Controlled-Release Fertilizer; Water-Soluble Fertilizer; Nutrient Leaching; Garden Performance; Longevity; Imaptiens walleriana
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4.
Asea, Godfrey Rox.
Genetic characterization of partial resistance and comparative strategies for improvement of host-resistance to multiple foliar pathogens of maize.
Degree: PhD, Horticulture and Crop Science, 2005, Ohio State University
► Foliar diseases are important biotic constraints limiting maize production globally. Northern corn…
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▼ Foliar diseases are important biotic constraints limiting maize production globally. Northern corn leaf blight (NCLB) incited by Exserohilum turcicum, gray leaf spot (GLS) incited by Cercospora zeae-maydis and maize streak incited by maize streak virus (MSV), are among the most destructive. Most of the maize foliar diseases are managed by means of quantitative partial resistance. Quantitative trait loci (QTL) conditioning partial-resistance to these pathogens have been identified. Validation of candidate QTL conferring partial resistance would present marker-assisted selection as a potentially viable strategy to improve host resistance. We were interested in determining the usefulness of molecular markers linked to consensus QTL controlling partial-resistance systems for improving the overall resistance level. We examined QTL for NCLB in chromosomal bins 3.06, 5.04 and 8.06; GLS QTL in bins 2.09 and 4.08; and a consensus MSV QTL in bin 1.04 as potential targets for selection in improving host resistance. We also examined the effectiveness of different selection strategies for the purpose of pyramiding resistance loci to these diseases. Field evaluations and subsequent selections were conducted independently for each disease in a population of 410 F2:3 lines derived from hybridization between inbred line CML202 with known resistance to NCLB and MSV, and VP31 a breeding line with known resistance to GLS. Maize streak evaluations were conducted in Zimbabwe, GLS tests were performed in Ohio, and NCLB evaluations were conducted in Uganda and Ohio. Genetic gains were calculated for simultaneous improvement of partial resistance following phenotype-based, marker-based, combined phenotype- and marker-based selection (MAS index), and random selection. Narrow-sense heritability estimates were 0.22, 0.25 and 0.39 for MSV, NCLB and GLS, respectively. Analysis of gene action using orthogonal contrasts showed mostly dominant gene action for NCLB, GLS and MSV. For NCLB, resistance due to presence of alleles from QTL in bins 3.06 and 5.04 was detected across two seasons. The chromosomal region in bin 4.08 for GLS resistance was significant (0.0001 ≤ P ≤ 0.0395) across seasons using late-season disease assessments. The major locus conferring resistance to MSV on chromosome 1 was significant (P<0.05) for resistance across seasons and explained 23% of phenotypic variations in the F2:4 generation. Phenotypic values associated with flanking markers at each locus based on interval analysis indicated that QTL in bin 4.08 for GLS, bin 1.04 for MSV, and bins 3.06 and 5.04 for NCLB significantly reduced disease severity. Our results validated the position and effect of four out of six QTL controlling partial resistance to these pathogens. This was consistent with the presence of homozygous alleles from the resistant parent. These results point out the need for validation of QTL in new populations and the potential of using marker-assisted selection for pyramiding resistance to several pathogens using target QTL.
Advisors/Committee Members: Pratt, Richard.
Keywords: Marker assisted selection; Maize; Host resistance; Foliar disease; QTL
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6.
Buenrostro-Nava, Marco T.
Characterization of GFP Gene Expression Using an Automated Image Collection System and Image Analysis.
Degree: PhD, Horticulture and Crop Science, 2002, Ohio State University
► Automated systems can be used to facilitate continual collection of biological information…
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▼ Automated systems can be used to facilitate continual collection of biological information from a large number of samples over long periods of time. The use of an automated system and image analysis would allow semi-continual monitoring and non-invasive quantification of the green fluorescent protein (GFP) expression and would therefore provide a better assessment of the levels of gfp gene expression than monitoring GFP at large time intervals. The main aim of this research was to monitor and quantify the expression of the gfp gene from the jellyfish (Aequorea victoria) and in vitro plant growth over time using an automated image acquisition system in combination with image analysis. The system, developed over the course of this work, consisted of a computer controlled two-dimensional positioning table and a charged-coupled device (CCD) camera mounted on a stereomicroscope equipped with a GFP fluorescence detection system. The image collection system was placed in a horizontal laminar air flow hood to provide an aseptic environment for monitoring in vitro cultures. In order to compare the pattern of expression of a soluble and an endoplasmic reticulum-targeted gfp gene, images of lima bean (Phaseolus lunatus L.) cotyledons transiently expressing the two different gfp genes, were collected every 30 min for 38 h. Time-lapse animations together with quantification of transient GFP expression using image analysis, showed that expression of the cytoplasmic soluble gfp gene was detected as early as 4 h after bombardment and reached a maximum at 24 h after bombardment. Expression of the endoplasmatic reticulum-targeted gfp gene was first observed 8 h after bombardment and reached its maximum expression after 24 h. The pattern of GFP expression, driven by the soybean lectin and 35S promoters, was monitored every 12 h for 28 d during somatic embryo development using the automated image collection system. Gene expression was then quantified using image analysis. Quantitative analysis revealed that, even though the lectin: gfp construction showed low levels of expression during early stages of development, expression levels eventually reached levels similar to those recorded from the 35S: gfp construction. Embryos with gfp under the regulatory control of the lectin promoter showed a peak of expression 47 days after embryo development, while GFP expression driven by the 35S promoter gradually increased throughout embryo development. Time-lapse animations were useful in characterization of gfp expression, and revealed a high variability in levels of gfp expression driven by the 35S promoter. Southern analysis showed the presence of multiple copies of the introduced plasmids for clones generated using particle bombardment. The copy number of clones containing the lectin: gfp construction, was not correlated with levels of gfp expression; however, a high copy number may have led to reduced levels of GFP expression of a clone containing the 35S: gfp construction.
Advisors/Committee Members: Finer, John J.
Subjects: Biology, Molecular
Keywords: Plant transformation; Analysis of gene expression; Image analysis; Robotics; Green fluorescent protein; Lima beans; Soybean; Wheat; Arabidopsis
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7.
Bumgarner, Natalie Ruth.
Abiotic Factors during Spring and Fall in Ohio: Their Measurement and Shaping of Lettuce Tissue Abundance and Composition.
Degree: PhD, Horticulture and Crop Science, 2012, Ohio State University
► The productivity of vegetable cropping systems can be assessed using multiple criteria.…
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▼ The productivity of vegetable cropping systems can be assessed using multiple criteria. Individual criteria tend to reflect the concerns of food suppliers, such as farmers, or consumers. Occasionally, steps taken to enhance productivity from a food supplier point of view result in losses from a consumer point of view and vice versa. Creating vegetable production systems that most effectively balance the interest of all within the food supply-consumption chain requires a thorough understanding of forces that shape various aspects of system productivity and efficiency. The need for such understanding is particularly high in the evaluation of emerging production systems such as ones operating fall through spring in the Great Lakes Region. Moreover, studies tend to focus on specific aspects of productivity and often address only a supply or consumption perspective. In this work, we set out to complete a more comprehensive assessment that would allow us to determine the potential for enhancing the value of so-called ‘off season’ vegetable production as a driver of economy and health. In two related studies, leaf lettuce crops were exposed to varied aerial and subsurface microclimates and nitrogen nutrition. Red-leaved romaine lettuce (Lactuca sativa) cultivars (Outredgeous, Flagship) were direct-seeded into raised beds in fall and spring in Wooster, OH. Multiple harvests were completed across the approximately 4 week experiments. Harvested tissue was frozen, and laboratory measures of anthocyanin, chlorophyll, soluble solids, vitamin C, and total antioxidant power were completed. Microclimate and nutrition impacted both lettuce biomass and composition across different seasons and years. This work encompassed the evaluation of microclimate management treatments using multiple criteria. The effort has improved the record of the impacts of microclimate management techniques on crops from physiological, production, and human health perspectives. A third study was completed in order to test the reliability of digital image analysis as a substitute for or supplement to destructive harvest and evaluation in assessing leafy crop yield. A reliable digital image analysis approach could have far-reaching implications for scientists and crop managers. Significant correlations between traditional destructive biomass and leaf area measures of leaf lettuce crops and pixel values of areas within digital images were noted. Techniques tested in this study were most effective when high color contrast was present between leaves and other material in the image and in images where complete leaf canopy closure had not occurred. Digital image analysis may be useful in real-time, non-destructive assessments of early-stage leaf lettuce canopy development. These studies provide evidence of the potential to alter, through root- and shoot-zone microclimate modification and nitrogen nutrition, and describe, through digital image analysis, leaf lettuce biomass accumulation and composition during fall and spring in the Midwest US. Treatments and techniques employed in this work are ready for on-farm use in altered or unaltered forms. Collectively, the results suggest that the capacity and efficiency of vegetable production systems and specific aspects of related research can be improved through microclimate management and digital analysis. It is also clear that multiple components of crop quality are influenced by crop management.
Advisors/Committee Members: Kleinhenz, Matthew D.
Subjects: Agriculture; Horticulture
Keywords: vegetable production systems; high tunnel; low tunnel; nutritional yield; season extension; off-season production; leaf lettuce
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8.
Cabrera, Antonio.
Genetic Analysis and Fruit weight QTL fine mapping in Sweet cherry (Prunus avium L.).
Degree: PhD, Horticulture and Crop Science, 2011, Ohio State University
► Apple, peach and strawberry are some of the most economically important fruit…
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▼ Apple, peach and strawberry are some of the most economically important fruit crops within the Rosaceae family. Nevertheless, the presence of gametophytic self-incompatibility system, long vegetative development and space requirement for some of these crops has hampered rapid improvement through traditional breeding. Despite active efforts in the Rosaceae community for developing genetic and genomic tools for rapid improvement, resources in cherry have lagged behind the major rosaceous crops. In an effort to improve tools for cherry breeding programs, we explored the suitability of the peach genetic and genomic resources to develop markers mapping to targeted regions of the sweet cherry genome. We used all available peach markers and mapped them to sweet cherry, however low marker transferability and inconsistencies between the physical and genetic peach maps hampered our progress for marker development in cherry. Since Conserved Orthologous sequences (COS) represent a set of genes that are conserved in sequence and copy number through plant evolution, we developed a set of rosaceous COS (RosCOS) for marker development cherry. Results from this study show that this set of markers provides enormous potential for marker development in the Rosaceae family and synteny analysis across families. To extend the use of these RosCOS to sweet cherry, we studied the level of polymorphism in breeding germplasm and developed the most extensive sweet cherry genetic map to date. Finally, the overall genome synteny between peach and cherry revealed by the RosCOS facilitated de development of cherry SNPs and SSRs markers to fine map a QTL region underlying phenotypic differences in fruit size in cherry. The map position of the fruit size QTL was narrowed down to a 1Mb region
Advisors/Committee Members: van der Knaap, Esther.
Subjects: Genetics
Keywords: Rosaceae, RosCOS, QTL, Prunus avium, Fruit weight
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9.
Chalfant, Patricia.
Responses of Grapevines to Timing and Method of Leaf Removal.
Degree: MS, Horticulture and Crop Science, 2012, Ohio State University
► Several winegrapes grown in cool climates, including Vitis vinifera Cabernet Franc and…
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▼ Several winegrapes grown in cool climates, including Vitis vinifera Cabernet Franc and Vitis sp. Chambourcin, benefit from crop reduction. The practice promotes timely fruit maturation and can improve fruit quality. Balanced pruning and cluster thinning are the cultural practices used to attain the desired crop load. However, crop reduction by cluster thinning is labor intensive, costly and typically not mechanized for winegrapes. In this study, the practice of early season leaf removal by hand and with a mechanized leaf remover is proposed as an alternate tool to reduce crop level, thereby optimizing crop load and fruit quality. The objectives were to determine the effects of the timing of leaf removal (pre-bloom, bloom, or fruitset) on yield components, crop load, fruit quality, and cold hardiness in Chambourcin and to 2) determine the effects of manual versus mechanical leaf removal at different phenological stages on yield components, growth, crop load, and fruit quality in Cabernet Franc. In Chambourcin, leaf removal at pre-bloom in 2010 and bloom in 2010 and 2011 reduced yield as compared to defoliation at fruitset and control (no removal). Early season leaf removal reduced crop load (Ravaz index) in both years. Defoliation at bloom increased bud lignification in both years and reduced bud injury in fall of 2010. Defoliation at pre-bloom reduced bud injury in winter in one of two years. In Cabernet Franc, manual leaf removal at pre-bloom and mechanical leaf removal at bloom reduced yield. Leaf removal had no negative effects on pH, titratable acidity, soluble solids, or total phenolics in either cultivar in either year. Early season leaf removal can be used to control yield without negatively impacting growth, cluster compactness, disease incidence, fruit composition, or lignification. It is concluded that early season leaf removal is a viable alternative to cluster thinning as a method of yield reduction in Chambourcin. Early season mechanical leaf removal is a viable alternative to manual leaf removal.
Advisors/Committee Members: Dami, Imed.
Subjects: Agriculture; Horticulture
Keywords: defoliation, leaf area, yield reduction, fruitset, crop load, fruit composition
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10.
Chanon, Ann Marie.
Studies on the reproductive capacity of Aesculus parviflora and Aesculus pavia: opportunities for their improvement through interspecific hybridization.
Degree: PhD, Horticulture and Crop Science, 2005, Ohio State University
► The genus Aesculus, of the family Hippocastanaceae, is comprised of thirteen species,…
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▼ The genus Aesculus, of the family Hippocastanaceae, is comprised of thirteen species, numerous botanic varieties, cultivars, and natural hybrids. All members of this genus are valued for their ornamental flowers. This research focused on the floral, pollen, seed, and reproductive biology of Aesculus parviflora and Aesculus pavia as the foundation for the development of an Aesculus improvement project. Both species exhibited andromonecy and expressed a sex ratio of approximately 5.5%. Aesculus pavia panicles contained fewer total flowers with the complete flowers located predominately in the basal portion of the inflorescence. Whereas, the complete flowers of A. parviflora panicles were located in the upper most apical portion of the panicle. There appeared to be some plasticity in floral sex expression since mechanical modification increased the number of complete flowers per panicle. Fresh pollen of all Aesculus tested germinated at acceptable levels greater than 80% across a broad range of sucrose concentrations and temperatures. The optimal conditions for germination were 20% sucrose and 15°C. Pollen germination following storage was not impacted by storage temperature but was significantly reduced with extended storage time. Overall seed germination and emergence for both A. parviflora and A. pavia were enhanced by a 60 day stratification period at 4°C. The 60 day stratification period improved the uniformity and increased the rate of the germination and emergence while minimizing the losses due to mold. Inadequate or extended periods of stratification resulted in seed deterioration. For both A. parviflora and A. pavia, the frequency of fruit set from both self and intraspecific pollinations was equal to or somewhat better than the fruit set for naturally occurring open pollination. In all cases, the success rate of fruit set for interspecific pollinations was quite low. Further work is needed to determine the basis for this poor fuit set and to develop techniques like embryo rescue in conjunction with traditional breeding methodologies for Aesculus improvement.
Advisors/Committee Members: Jourdan, Pablo.
Keywords: Aesculus; Bottle brush buckeye; Red Buckeye; floral biology; pollen viability; pollen storage; seed germination; seed stratification; hybridization
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11.
Chen, Zhenbang.
Biosynthesis and regulation of seroidal alkaloids in solanum chacoense.
Degree: PhD, Horticulture and Crop Science, 1999, Ohio State University
► Three steroidal alkaloids: solanidine (SD), leptinidine (LD) and acetylleptinidine (ALD) in Solanum…
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▼ Three steroidal alkaloids: solanidine (SD), leptinidine (LD) and acetylleptinidine (ALD) in Solanum chacoense Bitter, are toxic to insects and pathogens. The biosynthesis and regulation of these important compounds were studied using chemical, biochemical and physiological approaches. The stereochemistry of ALD was elucidated using 1H-1H nuclear magnetic resonance. The acetyl group at the C-23 position of ALD was located on the same side as C-18 methyl group and within the fold formed by D, E and F rings. Intact chloroplasts isolated from leaves of S. chacoense were incubated with alkaloid precursors [14C]-sodium acetate or [14C]-mevalonic acid. No radiolabelled LD and ALD were detected from the chloroplasts, but radiolabelled precursors were found to be converted into lipid-like compounds. Results suggested that the entire biosynthetic pathway from acetate (or mevalonic acid) to LD and ALD in S. chacoense may not occur in chloroplasts. A cell free extract of S. chacoense leaves was used as an enzyme source to incubate with LD and [3H]-acetyl CoA in various buffer systems. Autoradiography results revealed that the radiolabelled product separated by two-dimensional thin layer chromatography was an unknown compound with an Rf very close to ALD. Results indicate that the enzyme converting LD to ALD in S. chacoense is difficult to assay or isolate in vitro, or an alternative pathway of ALD biosynthesis may exist. LD and ALD levels in S. chacoense plants increased four- and 10-fold, respectively, after plants were transferred from Murashige and Skoog (MS) medium in vitro to soil-less Fafard mix and grown for 40 d; meanwhile SD level decreased 67%. When tissue culture plants were grown for 30 d on MS media containing jasmonic acid or methyl jasmonate, SD, LD and ALD levels increased three-, eight- and nine-fold, respectively, compared to the control. Abscisic acid increased LD and ALD by 60% and 100%, respectively; meanwhile arachidonic acid, salicylic acid and ethylene had no effect on SD, LD and ALD levels. Furthermore, plants grown on MS in unsealed culture jars, in blue light or containing silver nitrate accumulated more steroidal alkaloids than the controls. In summary, jasmonic acid and environmental factors are able to increase steroidal alkaloid levels in S. chacoense grown in vitro
Advisors/Committee Members: Miller, A. Raymond.
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13.
Clevenger, Josh.
Metabolic and genomic analysis of elongated fruit shape in tomato (Solanum lycopersicum).
Degree: MS, Horticulture and Crop Science, 2012, Ohio State University
► Tomato fruit shape is an important attribute as its shape informs how…
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▼ Tomato fruit shape is an important attribute as its shape informs how the fruit will be marketed and processed. Analysis of how fruit shape is regulated at the molecular level further provides insight into the molecular regulation of early fruit development. We have developed near isogenic lines (NILs) in the wild species (S. pimpinellifolium) background for seven major fruit shape and weight genes, SUN, OVATE, fs8.1, FAS, LC, FW2.2, and FW3.2. Analysis of the SUN, OVATE, and fs8.1 triple NIL shows that all three genes control fruit shape in an additive manner, and SUN exhibits additive-by-additive interaction with OVATE and fs8.1 in controlling fruit shape. All three genes together made a significantly longer fruit. Using an unbiased classification using Elliptic Fourier Coefficients and unsupervised Bayesian clustering we further show that all 27 genotypes produce fruit shapes that can be assigned to six distinct classes, and that membership of these genotypes to these classes reinforces the genetic data. Concurrently, we fine mapped fs8.1 further to a 3 Mb region. It is not fully known how SUN controls fruit elongation at the molecular level. We used metabolite and gene profiling during early fruit development to identify metabolite and gene regulatory networks and to infer the relationship of these networks in round and elongated fruit. We identified distinct metabolite and gene expression regulatory networks, and found that new associations were made in elongated fruit. Analysis of gene expression networks revealed a complex interaction between hormone homeostasis, secondary metabolism, and cell wall modification. These data led us to propose a hypothetical model of the effect of SUN on early fruit development leading to elongated fruit shape.
Advisors/Committee Members: van der Knaap, Esther.
Subjects: Plant Biology
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14.
Coaker, Gitta Laurel.
Genetic and biochemical characterization of resistance to bacterial canker of tomato caused by Clavibacter michiganensis subsp. michiganensis.
Degree: PhD, Horticulture and Crop Science, 2003, Ohio State University
► Bacterial canker of tomato, caused by Clavibacter michiganensis subsp. michiganensis ( Cmm…
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▼ Bacterial canker of tomato, caused by Clavibacter michiganensis subsp. michiganensis ( Cmm ), is a devastating disease that proliferates in tomato xylem vessels. This research was initiated to genetically and biochemically characterize two quantitative trait loci (QTL) from Lycopersicon hirsutum accession LA407, Rcm2.0 and Rcm5.1, that confer partial resistance to Cmm . Research conducted in this dissertation tested the hypothesis that both loci confer resistance through differing mechanisms. A recurrent selection program was employed during QTL detection to simultaneously advance breeding material while mapping loci and testing genetic hypotheses. The precise genetic location of Rcm2.0 and Rcm5.1 was determined by interval mapping techniques and the analysis of recombinant families. Rcm2.0 was positioned to a 4.4 cM interval on chromosome 2 while Rcm5.1 was positioned to a 2.2 cM interval on chromosome 5. Both loci exhibited additive gene action and interact epistatically. A difference in vascular morphology between resistant LA407 and susceptible cultivated lines was observed. Single marker-QTL analysis revealed that Rcm2.0 and the QTL from LA407 controlling an increased rate of vascular development and maturation both map to the same genetic location. Thus, Rcm2.0 may confer resistance due to a faster maturing and therefore more resistant vascular system. Protein expression was analyzed during Cmm infection using the technique of two-dimensional polyacrylamide gel electrophoresis (2-DE). Forty-one differentially expressed proteins were identified by mass spectral analysis. The accumulation of specific proteins depended upon genotype and time post-inoculation. Rcm2.0 and Rcm5.1 induced the appearance of specific proteins, providing supporting evidence that these loci confer resistance through distinct mechanisms. Cmm cultures were also analyzed to identify Cmm proteins expressed in planta and to gain a greater understanding of Cmm protein expression. Although I was unable to identify Cmm proteins expressed in planta , reproducible differences in protein expression between growth phases was detected. Mass spectral analysis identified 15 out of 16 proteins by analysis of DNA sequences in publicly available genome databases. This illustrates the feasibility of protein identification by analyzing sequence data from closely related organisms. The differentially regulated proteins identified can be pursued in future experiments to determine their role in Cmm virulence.
Advisors/Committee Members: Francis, David M.
Keywords: quantitative trait loci; marker-assisted selection; quantitative disease resistance; vascular morphology; 2-DE; two-dimensional polyacrylamide gel electrophoresis; mass spectrometry
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15.
Coffman, Reid Richards.
Vegetated roof systems: design, productivity, retention, habitat, and sustainability in green roof and ecoroof technology.
Degree: PhD, Horticulture and Crop Science, 2007, Ohio State University
► The environmental technology of vegetated roof systems depends on collaboration between designers…
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▼ The environmental technology of vegetated roof systems depends on collaboration between designers and scientists. But this collaboration is difficult to carry out due to well-entrenched differences in disciplinary methods. To compensate this dissertation attempts to improve our conceptualization and dissemination of vegetative roof system projects and to extend our scientific knowledge of how these systems function. In Chapter 1, I identify current problems and offer designers a framework for the conceptualization of ecoroof projects and dissemination of knowledge about such systems. I propose a design-research framework for the inclusion and communication of research agendas into design projects. In Chapter 2, I describe the first scientific study, which was designed to evaluate experimentally the effect of substrate depth on net primary productivity, water retention, and water quality. My data revealed that deep substrate roofs retained 18% more rainwater while producing 2.5 times more biomass than shallow substrate roofs. Roofs using water recycling or run-on water produced up to 26% more biomass than those receiving only direct precipitation and did so without any significant reduction in retention. In Chapter 3, I quantify animal diversity on two vegetated roof systems using rapid assessment method for insects, spiders and birds. The Rènyi family of diversity indices was used to compare diversity between the two ecoroofs. My data revealed relatively low similarity between the species assemblages, but a relatively strong similarity in community structure. Overall, the intensive ecoroof supported slightly higher diversity. Finally, in Chapter 4, I use emergy analysis to quantify and compare the sustainability of three vegetated roof systems: an agricultural roof garden, a shallow-substrate ecoroof, and a deep-substrate ecoroof. The shallow-substrate ecoroof was the most sustainable (least unsustainable) of the three, followed by the deep-substrate ecoroof and the agricultural roof garden. All three systems were less sustainable than various agricultural practices, while being more sustainable than conventional landscapes, urban gardens and cities. These results confirm that vegetated roof systems can improve the sustainability of a city, but are reliant on many non-renewable resources for their construction and upkeep.
Advisors/Committee Members: Pasian, Claudio C.
Keywords: Green roof, design, sustainability, sustainable design, sustainable development
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16.
Contreras, Samuel A.
Effects of maternal plant invironment on lettuce (lactuca sativa l.) seed dormancy, germinability, and storability.
Degree: PhD, Horticulture and Crop Science, 2007, Ohio State University
► Seed dormancy, germinability and storability are important aspects of seed quality determined…
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▼ Seed dormancy, germinability and storability are important aspects of seed quality determined by the genotype and environment during seed development. Lettuce is one of the most important vegetables in the world and high quality seed is required for successful crop establishment. However, seed thermoinhibition and photodormancy are two properties commonly affecting germination speed and uniformity of many lettuce genotypes. The main objectives of this study were to determine the effects that maternal plant conditions have on different aspects of lettuce seed quality such as germinability and storability. In separated experiments, ‘Tango’ lettuce seeds were produced in contrasting conditions for the following environmental factors: i) water availability, ii) day-length, iii) light quality (red to far-red [R:FR] ratio), and iv) temperature. Restricted water availability during lettuce seed production had little effects on most aspects of seed quality, although a significant increase in seed weight and the production of fewer seeds per plant were observed. Additionally, water productivity (seed yield per volume of water consumed) increased significantly in response to restricted water availability, which is especially important for lettuce seed producers which are located mainly in arid regions. Seeds produced at higher temperatures (30/20°C vs. 20/10°C) had higher storability and lower thermoinhibition, photodormancy, and dry weight. Temperature effects on seed germinability occurred during the first phase of seed development (cell division and histo-differentiation), while effects on seed storability occurred at the last phase of seed development (maturation drying). The aspect of the maternal plant light environment that had the greatest effects on seed quality was the R:FR ratio. Seeds produced under higher R:FR ratios had higher germinability, poorer storability, lower sensitivity to external abscisic acid (ABA), and lower ABA concentrations. These effects occurred during the last phase of seed development (maturation drying, after physiological maturity) and I hypothesized that higher accumulation of the active form of phytochrome (Pfr) in seeds drying under red-rich light would be involved in these responses. My results suggest that seed production under light environments with higher R:FR ratios represents a novel approach to the production of lettuce seed with lower levels of thermoinhibition and photodormancy.
Advisors/Committee Members: Bennett, Mark A.
Subjects: Agriculture, Agronomy
Keywords: Seed quality; Seed production; Photodormancy; Thermoinhibition; Abscisic acid; Light quality; Red to far-red ratio
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17.
Correa, Valdir Ribeiro Mr.
FUNCTIONAL GENOMICS OF PANTOEA STEWARTII SUBSP. STEWARTII AND PARTIAL GENOME SEQUENCE OF THE MAIZE STOLBUR PHYTOPLASMA SOLANI, TWO INSECT-TRANSMITTED BACTERIAL PATHOGENS OF MAIZE.
Degree: PhD, Horticulture and Crop Science, 2010, Ohio State University
► Stewart’s wilt and maize redness (MR), caused by the bacterial pathogens Pantoea…
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▼ Stewart’s wilt and maize redness (MR), caused by the bacterial pathogens Pantoea stewartii subsp. stewartii (Pnss) and stolbur phytoplasma (Candidatus Phytoplasma solani), are two important diseases of maize. MR, endemic to Eastern Europe, can cause yield losses of 40-90%. Although most U.S. maize hybrids are resistant to Pnss, the disease is important because of strict quarantine restrictions for seed exportation. Moreover, Pnss makes a good model system for bacteria-host interactions due to vast genomic and genetic resources. A better understanding of the biology of these pathogens could provide new avenues for disease management and discovery of key mechanisms of pathogen-host interactions. Gram-negative bacterial pathogens of eukaryotes often secrete effector proteins directly into host cells via a needle-like protein channel called ‘type III secretion system’ (T3SS), and bacteria adapted to either animal or plant hosts use phylogenetically distinct T3SSs for secreting proteins. We found that Pnss carries two type-three secretion systems that enable it to invade both animal and plant hosts. In addition to a Hrp-type T3SS, known to be essential for maize pathogenesis, Pnss has a second T3SS (PSI-2) that is required for persistence in its flea beetle vector, Chaetocnema pulicaria. Mutagenesis of the PSI-2 psaN gene, essential for building the T3SS, greatly reduced Pnss persistence in insect guts, and its transmission to maize. Complementation of the psaN gene reversed these phenotypes. When mechanically inoculated, the Pnss mutant was fully virulent on maize, indicating that PSI-2 is not required for plant pathogenicity. Our findings demonstrate that the two T3SSs in Pnss play different roles in the life cycle of this bacterium as it alternates between insect and plants. Information on stolbur phytoplasma genome sequences regulating host and vector specificity is lacking. It has been shown that the maize-infecting stolbur phytoplasma, transmitted by Reptalus panzeri, causes phenotypically different symptoms on indicator plants, as compared to stolbur normally associated with solanaceous hosts and transmitted by Hyalesthes obsoletus, suggesting genetic differences in its genome. This difference may be linked to a shift in the stolbur population infecting maize and R. panzeri. To address this question and to expand genomic resources for stolbur, we used Illumina® sequencing to obtain sequences of stolbur infected maize plant. About 0.735 Mb of the predicted 0.85 Mb of the stolbur phytoplasma genome was sequenced. The sequence contained 764 predicted open reading frames, with 51% of the protein coding sequences being functionally assigned. Genes known to be present in potential mobile units and genes encoding secreted proteins were identified. Stolbur phytoplasma specific sequences that may be used for diagnostic purposes were also identified. Overall, our findings provide additional information on mechanisms Pnss uses to interact with its insect vector and may prompt the exploration of the life cycle of these and other bacterial pathogens in search of currently unknown alternate host species that in the case of human pathogens is relevant to assess food security. It also provides new genomic resources to better understand stolbur phytoplasma interactions with its plant and insect hosts.
Advisors/Committee Members: Pratt, Richard.
Subjects: Plant Pathology
Keywords: T3SS; effector proteins; Pantoea stewartii; insect vector; colonization; maize stolbur; Illumina; genome sequencing.
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18.
Da Cunha, Luis.
Structural insights into the Function of the Arabidopsis protein RIN4, a multi-regulator of plant resistance against bacterial pathogens.
Degree: PhD, Horticulture and Crop Science, 2009, Ohio State University
► The plant innate immune system consists of two main branches, PAMP-triggered immunity…
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▼ The plant innate immune system consists of two main branches, PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI). Perception of pathogen-associated molecular patterns (PAMPs) activates PTI. However, pathogenic bacteria deploy virulence factors that suppress PTI, including translocated type III effector (T3E) proteins. In addition to suppressing PTI, T3Es also activate the second branch of plant innate immunity, ETI, via activation of NB-LRR disease resistance proteins. ETI can be indirectly activated by PTI-suppressing T3Es. For instance, the Arabidopsis protein RIN4, which negatively regulates PTI, is targeted by the three sequence unrelated T3Es AvrRpm1, AvrB, and AvrRpt2 from P. syringae that suppress PTI. Additionally, RIN4 mediates recognition of these T3Es via the NB-LRR proteins RPM1 and RPS2. AvrRpm1 and AvrB phosphorylate RIN4, and AvrRpt2 cleaves it. RIN4 interacts in planta with, RPM1 and RPS2, and perturbation of RIN4 elicits their response to these T3Es. Structure-function analysis of RIN4 has revealed that (1) RIN4 has multiple domains capable of negatively regulating PTI; (2) one of these domains is critical for regulation of RPM1; (3) membrane targeting of RIN4 differentially affects its ability to regulate PTI and ETI; and (4) RIN4 differentially regulates RPM1 and RPS2. Collectively, our results indicate that RIN4 is multifunctional with separable activities involved in regulation of these two central branches of plant immunity.
Advisors/Committee Members: Mackey, David.
Subjects: Plant pathology
Keywords: Plant resistance; PTI; R-gene; Pseudomonas; RIN4
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19.
Darrigues, Audrey.
Dissecting variation in tomato fruit color quality through digital phenotyping and genetic mapping.
Degree: PhD, Horticulture and Crop Science, 2007, Ohio State University
► Color is an important attribute of processing tomatoes. Color and color uniformity…
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▼ Color is an important attribute of processing tomatoes. Color and color uniformity are affected by yellow shoulder disorder (YSD), a ripening disorder that results in discoloration of the proximal end tissues of the fruit. We show lycopene content was reduced by 13-24% in juice from non-YSD tomato. Beta-carotene content was reduced by 4-8% in juice from YSD-affected tomato, although this reduction was not statistically significant. Quantification of carotenoid content was more precise by increasing biological replications rather than analytical replications. To assess genetic contributions to YSD, a color measurement module in the Tomato Analyzer software was tested to quantify color and color uniformity from digital images. This approach improved the efficiency of collecting data, provided high correlations with data collected by colorimeter, and improved estimates of genetic contributions to color. With increased precision and accuracy in measuring color, sampling strategies for higher carotenoid content can be optimized and the genetics of color uniformity in tomato can be uncovered. To elucidate the genetics of YSD, molecular markers were developed and exploited for breeding application. An advanced backcross population (BC2) derived from Solanum lycopersicum (OH88119) x S. pimpinellifolium (PI128216) was evaluated for color. Indices were developed to circumvent the highly correlated traits and to simplify the trait complexity based on principal component analysis. These indices capture the essential features of color intensity and color uniformity. The BC2 population was genotyped with 70 markers for QTL analysis. The population was selfed through four generations to generate an inbred backcross population (BC2S4), which was evaluated for the same traits and genotyped with the same markers as the BC2 population. An F2 population and elite varieties were evaluated for color to confirm the QTL. We found QTL for color intensity on chromosomes 2, 8, and 9, and a QTL for color uniformity on chromosome 6. Positive gain under selection was realized for selection by phenotype and by marker-assisted selection (MAS). Higher gains were realized from MAS. Directional selection strategies are being used to further characterize these QTL and evaluate genetic correlations to other fruit quality traits, disease resistance, and yield.
Advisors/Committee Members: Francis, David M.
Subjects: Agriculture, Agronomy
Keywords: TOMATO; COLOR; YELLOW SHOULDER DISORDER; LYCOPENE; TOMATO ANALYZER; QTL MAPPING
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20.
Dhillon, Taniya.
Molecular and genetic analyses of freezing tolerance in the Triticeae cereals.
Degree: PhD, Horticulture and Crop Science, 2012, Ohio State University
► Freezing tolerance and winter hardiness are complex traits. Over the course of…
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▼ Freezing tolerance and winter hardiness are complex traits. Over the course of the last 100 years different genetic tools have been employed with cereals of the Triticeae to gain insight into the complex nature of these traits. Emerging from many independent studies are findings that large affects are contributed by two regions on group five chromosome homoeologs, now identified as Frost Resistance-1 (FR-1) and FR-2. The FR-2 locus encompasses a cluster of genes encoding at least 11 different C-Repeat Binding Factor (CBF) proteins while FR-1 exerts negative control over expression of the CBF genes at FR-2. Recently we determined the physical structure of collinear segments of the FR-H2 region from four barley cultivars. Two of these were from freezing-tolerant winter-hardy genotypes and two of these were from less freezing-tolerant nonwinter-hardy genotypes. A key finding was that the genomic region encompassing subsets of the genes at FR-H2 is amplified to multiple copies occurring in tandem in the freezing-tolerant winter-hardy genotypes whereas the collinear genomic regions in spring genotypes occur in single copy. Other data suggest increased copy numbers are associated with increased transcript levels of the other CBF genes at FR-H2. Our data also indicate CBF copy number variations in wheat. Taken together, these data suggest that CBF copy number variation is a recurring theme in the Triticeae, and that total CBF copy number rather than a particular CBF may be the molecular basis underlying FR-2.
Advisors/Committee Members: Stockinger, Eric J.
Subjects: Molecular Biology; Plant Biology
Keywords: Freezing tolerance, CBF, barley, wheat, Triticeae
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21.
Dimke, Kelley C.
Valuation of Tree Canopy on Property Values of Six Communities in Cincinnati, Ohio.
Degree: PhD, Horticulture and Crop Science, 2008, Ohio State University
► The value of the urban forest as a component of the urban…
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▼ The value of the urban forest as a component of the urban environment is significant. Environmental benefits of the urban forest include improved air quality, energy conservation through reduction of heating and cooling costs, climate moderation, flood control, reduction in noise levels and wildlife habitat. The urban forest also provides many social benefits. Studies have shown that trees reduce stress and improve the physical health of urbanites. Financial support for urban forestry in many cities is on the decline. The objective of this research was to evaluate the impact trees have on property values of six communities (Bond Hill, Carthage, Clifton, Hyde Park, Kennedy Heights and North Avondale) of varying socio-economic levels in Cincinnati, Ohio. Tax assessor records were obtained from property sales between the years 2000 and 2005. One hundred sites were randomly selected from each of the six communities. Data were collected from each site during the winter as well as the summer months. Dominant genus, caliper of dominant genus, estimate of tree cover, and overall property maintenance were recorded. Using the hedonic method of cost benefit analysis it was determined that each percentage increase in tree cover added $783.98 to the property value. The average value of tree canopy across the 600 sites is $20,226 or 10.7% of the sale price of the home. The findings from this research will be useful to Urban Forestry Departments in their requests for funding.
Advisors/Committee Members: Gardner, David.
Subjects: Horticulture; Landscaping; Urban planning
Keywords: tree canopy; property values; hedonics; urban forestry
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22.
Dimke, Kelley C.
Effect of overwintering systems on 30 species of herbaceous perennials.
Degree: MS, Horticulture and Crop Science, 2005, Ohio State University
► Herbaceous plants grown in decorative containers in a northern United States summer…
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▼ Herbaceous plants grown in decorative containers in a northern United States summer season have traditionally consisted of annual and tropical species. There has been an increasing trend in residential landscaping to utilize perennials along with annuals and tropicals in mixed containers. With this increased use comes an increased interest in overwintering perennials for use the following year. The objective of this research was to evaluate the survivability and quality of 30 perennial species with a USDA hardiness rating of zone 3, 4, or 5. Perennials were selected based on length of bloom, foliage interest, and architectural form. Three overwintering treatments were used: containers left outside, containers overwintered in an un-heated building, or plants overwintered in the ground. Perennials were transplanted on June 16, 2003 in Columbus, Ohio (USDA Hardiness Zone 5b). Plant quality, plant height and flowering time were recorded on April 16, 2004 and May 17, 2004. Twenty-one species were successfully overwintered inside the un-heated building. Thirteen species in the container treatment overwintered inside were rated equal to or higher than the in ground treatment. Ceratostigma plumbaginoides, Kniphofia Pfitzer’s Hybrid, Leucanthemum xsuperbum ‘Snowcap’, and Stokesia laevis ‘Honeysong Purple’ rated significantly higher when overwintered in containers stored inside than in the ground. Flowering time and height measurement differences were not significant. Coreopsis ‘Limerock Ruby’, Diascia integerrima Coral Canyon™ and Gaura lindheimeri ‘Siskiyou Pink’ did not survive in any treatment. None of the species tested, with the exception of Sedum ‘Matrona’, survived the outside container treatment. Overwintering certain species of perennials inside an unheated building such as an unheated garage is a viable option for homeowners to improve survival. Species used were: Alchemilla mollis ‘Thriller’, Anemone tomentosa ‘Robustissima’, Calamagrostis xacutiflora ‘Overdam’, Ceratostigma plumbaginoides, Coreopsis ‘Limerock Ruby’, Crocosmia xcrocosmiiflora ‘Lucifer’, Diascia integerrima Coral Canyon™, Epimedium xrubrum, Euphorbia amygdaloides var. robbiae, Gaura lindheimeri ‘Siskiyou Pink’, Geranium sanguineum ‘Alpenglow’, Heuchera americana ‘Palace Purple’, Heuchera sanguinea ‘Splendens’, Hosta ‘Francee’, Hosta ‘June’, Hypericum calycinum, Kniphofia Pfitzer’s Hybrid, Lamiastrum galeobdolon ‘Variegatum’, Lamium maculatum ‘Anne Greenway’, Lavendula angustifolia ‘Munstead’, Leucanthemum xsuperbum ‘Snowcap’, Nepeta xfaassenii ‘Dropmore’, Panicum virgatum ‘Shenandoah’, Phlox paniculata ‘Mt. Fuji’, Scabiosa caucasica ‘Butterfly Blue’, Sedum ‘Matrona’, Stachys byzantina ‘Big Ears’, Stokesia laevis ‘Honeysong Purple’, Thymus serphyllum ‘Annie Hall’, Veronica alpina ‘Alba’.
Advisors/Committee Members: Still, Steven M.
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24.
Doong, Tzyy-Jye.
Regulation of Gibberellin Metabolism by Environmental Factors in Arabidopsis Thaliana.
Degree: PhD, Horticulture and Crop Science, 2002, Ohio State University
► Environmental factors such as light and temperature play an important role in…
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▼ Environmental factors such as light and temperature play an important role in plant development. The bolting response associated with flowering in Arabidopsis and other rosette species is regulated by gibberellin (GA). Presumably there are one or more blocks in the GA biosynthetic pathway that are removed following induction of flowering by either long-days (LD) or vernalization. The objective of this research was to identify steps in biosynthesis regulated by photoperiod and vernalization in Arabidopsis thaliana by comparing the biological activities of native GAs and GA precursors under inductive and non-inductive condition. A T-DNA tagged dominant mutant with a cold requirement line (CR) and a recombinant inbred line selected for a LD requirement (CS933) were used. Quantitative analysis of the content of kaurenoic acid (KA) in these two environmental responsive types when plants were subjected to inductive conditions did not support the hypothesis that the GA biosynthesis pathway is regulated in the conversion of KA to 7-OH KA in Arabidopsis. For 20 carbon GAs, a common feature that distinguished between active and inactive compounds was the oxidation state of C-20. GA precursors and GAs containing a C-20 methyl group (GA12) were not active, while GAs containing a C-20 aldehyde (GA24 and GA36) had substantial biological activity when applied to non-induced plants of both response types. This result suggests that the limiting step in GA biosynthesis pathway is located at the step in which the C-20 carbon is oxidized. In addition, for both 19 and 20 carbon GAs, C13 hydroxylation resulted in reduced biological activity when compared to the non-C13 hydroxylated homologs. These results suggest that 1) under non-inductive conditions C-20 oxidation is the rate-limiting step in the synthesis of bioactive GAs; 2) both vernalization and LD regulate GA biosynthesis at the same control point; 3) the non-C13 hydroxylation pathway leading to GA4 may be more important in regulating stem growth than the early C13 hydroxylation pathway leading to GA1.
Advisors/Committee Members: Metzger, James D.
Subjects: Biology, Plant Physiology
Keywords: Arabidopsis; Photoperiodism; Vernalization; Gibberellin; Hormone
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25.
Ferraro, Fernanda Pereira.
Pasture growth analysis: the relationship between herbage mass and herbage accumulation rate.
Degree: MS, Horticulture and Crop Science, 2010, Ohio State University
► The frequency and intensity of herbage defoliation have been the focus of…
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▼ The frequency and intensity of herbage defoliation have been the focus of grassland research because of their effect on herbage accumulation rate (HAR). The Gompertz equation describes standing herbage mass (HM) over time and its derivative describes the HAR. By combining those two relationships, a time-independent relationship can be developed between HAR and HM. The objectives of this research were: i) develop Gompertz growth curves and their time independent form, ii) investigate the seasonal pattern in those equation parameters, iii) use the time independent parameters to create a model to predict HAR based on HM, iv) validate the model, and v) investigate factors affecting the calibration of the rising plate meter (RPM) for measuring HM in pastures. In 2008, HM was measured weekly during 11 growing periods at Columbus and Coshocton, OH, and Arlington, WI. Those data were fit to Gompertz equations and time-independent HAR vs HM curves were calculated, and subsequently, the optimum HM at which HAR was maximized was determined. The optimum HM varied between 1600 and 4000 kg DM ha-1 and there was a seasonal pattern of the parameters of the Gompertz equation and its time-independent form. The parameters from the time-independent function of HAR vs HM were used to develop a model to predict HAR based on the standing HM, and a study was conducted from 20 May to 27 October near South Charleston, OH to calibrate the model parameters and validate the model predictions. Monoculture plots of tall fescue [Schedonorus phoenix (Scop.) Holub.] (TF), orchardgrass (Dactylis glomerata) (ORG), Kentucky bluegrass (Poa pratensis) (KBG) and a mixture (MIX) of those three species were subjected to four defoliation treatments: 3600 to 2800 kg DM ha-1 (Tall-Tall, TT), 3300 to 2400 kg DM ha-1 (Tall-Short, TS), 3600 to 1800 kg DM ha-1 (Hay) and 3000 to 1600 kg DM ha-1 (Variable, V). The proportion of variation explained by the regressions of observed on predicted model values for HM ranged from 0.48 to 0.88 and 11 out of 25 regressions were not significant different for m = 1 and c = 0. For treatments Hay and V, the model underestimated the standing HM, whilst overestimated HM in treatments TT and TS. The model showed promise in predicting the effect of defoliation on subsequent HAR; however, some refinement is required, especially when predicting herbage accumulation at residual herbage mass lower or about to 1600 kg DM ha-1. The effect of season and species on the RPM calibrations were studied in five Ohio environments: Columbus 2008 and 2009, two sites at Coshocton in 2008 and South Charleston in 2009. There was an effect of calendar week (P = 0.0021), environment (P < 0.0001), environment x week (P < 0.0001), and at South Charleston species (P = 0.0078) on HM. A pattern of rapidly decreasing of slope coefficient was observed in spring followed by increasing coefficients the remainder of the season, suggesting the existence of underlying processes responsible for the seasonal changes.
Advisors/Committee Members: Sulc, R. Mark.
Subjects: Agronomy
Keywords: herbage accumulation rate; Gompertz curve; rising plate meter; forage management
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26.
Figueroa, Rodrigo.
Biology and management of common groundsel (senecio vulgaris L.) in strawberry.
Degree: PhD, Horticulture and Crop Science, 2003, Ohio State University
► Common groundsel (Senecio vulgaris L.) is an annual weed of Mediterranean origin…
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▼ Common groundsel (Senecio vulgaris L.) is an annual weed of Mediterranean origin that has become a worldwide pest in many crop production systems, including small fruit crops like strawberry. Management of common groundsel has been difficult because of its tolerance of many control measures and resistance to some herbicides, and because of inadequate or conflicting information about its biology. Studies were conducted in Ohio to determine the effect of common groundsel’s maternal environment on seed dormancy, describe the pattern of seedling emergence and seed persistence, and to evaluate the response of common groundsel and strawberry to herbicides. Experiments were conducted using local seeds and seeds collected along a 700-km transect from Michigan to Kentucky. Freshly matured seeds collected from sites along this transect differed in germination response to temperature, but when plants from these sites were grown in a common environment the seeds responded uniformly to temperature. In growth chamber studies, seeds maturing on plants growing in cold short day conditions were mostly dormant whereas seeds produced on plants in warm long day conditions were mostly non-dormant. Changing temperature conditions from warm to cold increased seed dormancy, especially when the change occurred in early reproductive stages. The dormancy status of buried seeds varied throughout the year, mostly in response to soil temperature. Seedling emergence was limited by both rainfall and temperature but there was an interaction with tillage. A logistic regression model demonstrated that in tilled soil, emergence was stimulated by small amounts of rainfall, but in no-till conditions about ten-times as much rainfall is required to stimulate emergence. Nearly all buried seeds germinated or died during two years of burial in soil. In newly established strawberries, common groundsel was controlled with the herbicide sulfentrazone (N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl-]phenyl]methanesulfonamide) applied before seedling emergence at rates of 0.15 and 0.3 kg/ha. Stunting was observed in strawberry plants as herbicide rates increased, and was more severe on a high pH (> 6.5) soil and on cultivar ‘Allstar’ compared with ‘Jewel’. Late summer applications of clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) herbicide (0.1-0.2 kg/ha) controlled common groundsel without suppressing strawberry foliage or reducing yield.
Advisors/Committee Members: Douglas, Doohan J.
Subjects: Agriculture, Agronomy
Keywords: maternal environment, seed dormancy, sulfentrazone, clopyralid, weed emergence, seed longevity
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27.
Gesimba, Robert Morwani.
Screening Passiflora Species For Drought Tolerance, Compatibility With Purple Passion Fruit, Fusarium Wilt Resistance And The Relationship Between Irrigation, Drenching And Media Composition In The Control Of Fusarium Wilt.
Degree: PhD, Horticulture and Crop Science, 2008, Ohio State University
► Drought and Fusarium wilt are the main constraints in growing purple passion…
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▼ Drought and Fusarium wilt are the main constraints in growing purple passion fruit (Passiflora edulis) in Kenya. There is need for drought and Fusarium wilt-resistant rootstock. In an effort to develop a drought and Fusarium wilt resistant Passiflora rootstock, a series of experiments were conducted at The Ohio State University and Egerton University in Kenya, to study vegetative propagation, graft compatibility, drought tolerance, Fusarium wilt resistance in Passiflora species and to identify an integrated control method for Fusarium wilt. In the vegetative propagation, graft compatibility and drought tolerance studies, 20 Passiflora species were screened. Species of the subgenus Passiflora rooted in higher percentages than species of the Decaloba subgenus (81 vs 64%). Cuttings from vines and liana type species rooted in higher percentages than cuttings from annual species when treated with 0.1% indole-3-butyric acid powder (82, 73 vs 44%). Cuttings of Passiflora gerbertii L., Passiflora caerulea L. and Passiflora subpeltata Ortega. could be rooted in high percentages and were compatible rootstocks with the purple passion fruit. Passiflora incarnata, P. caerulea and P. subpeltata had higher drought-tolerance than the other species. In the Fusarium wilt resistance studies, nine Passiflora species were screened using Fusarium oxysporum f. sp. passiflorae isolates from four locations in Kenya. Passiflora edulis f. flavicarpa and P. suberosa were resistant to Fusarium wilt implying that the P. edulis f. flavicarpa plants currently being used by farmers may not be true-to-type and hence susceptible. Passiflora incarnata and P. mollisima were moderately resistant to Fusarium wilt. Passiflora suberosa, P. incarnata and P. caerulea can be improved for use as rootstock alternatives for purple passion fruit. For Fusarium resistant P. suberosa, breeding should focus on improving graft compatibility and drought tolerance. For drought-tolerant P. incarnata, improvement should focus on improving compatibility and Fusarium wilt resistance. Since P. caerulea is compatible with P. edulis and is drought-tolerant, improvement should focus on Fusarium wilt resistance. In the study the effect of irrigation and substrate type in the occurrence and suppression of Fusarium wilt in a passion fruit orchard, two substrates, native soil in Kenya and a formulated substrate comprising of 20% soil, 60% pumice and 20% decomposed bovine manure were evaluated. Substrate treatment was by pasteurization, or three chemicals; Root-guard and Rodozin (both under trials) with Terraclor Super® as a commercial control. Irrigation methods comprised of a novel integrated container-irrigation system (ICIS-pot) and black plastic mulch with integrated irrigation system (ICIS-mulch), micro irrigation (dripper), basin irrigation and no irrigation as control. Three month old seedlings were inoculated with 2.0 x 106 cfu. of Fusarium oxysporum f. sp. passiflorae macroconidia obtained from infected passion fruit plants. ICIS-pot and ICIS-mulched plots in the field and greenhouse as well as plots treated with Root-guard and Rodozin had low pathogenic Fusarium colony populations. Also ICIS-mulched plots had the highest colony populations of non-pathogenic Fusarium per gram of substrate. In the greenhouse and field, the ICIS-pot and ICIS-mulch irrigation methods significantly reduced Fusarium wilt occurrence 75 days after substrate treatment. ICIS-pot irrigated passion fruits had longer vines in the field. Thus, the use of ICIS-pot and ICIS-mulch together with either Rodozin or Root-guard treatment give short term suppression of Fusarium wilt and increase passion fruit vegetative growth.
Advisors/Committee Members: Struve, Daniel.
Keywords: Passiflora, drought, rootstocks, Fusarium wilt.
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28.
Gillilan, Jo Anna.
IMPROVEMENT OF U.S. EPA MINIMUM RISK ESSENTIAL OILS’ PESTICIDE ACTIVITY THROUGH SURFACTANT ENHANCEMENT AND SYNERGY.
Degree: PhD, Horticulture and Crop Science, 2012, Ohio State University
► Plant essential oils have been used since antiquity for many purposes, including…
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▼ Plant essential oils have been used since antiquity for many purposes, including pest control in agriculture and against nuisance pests such as mosquitoes, flies and ticks. In recent years, consumers have increasingly expressed interest in purchasing organically grown foods, as well as using natural and naturally derived materials to eradicate pests in their lawn, garden and homes. In 1996, the U.S. Environmental Protection Agency established a list, referred to as the 25(b) list, containing 31 active ingredients deemed minimum risk. Companies developing pesticides using active ingredients from the 25(b) list are exempt from federal registration requirements, providing a financial incentive to develop such products as well as fill growing consumer demand. There are 14 plant essential oils and essential oil constituents on the 25(b) list with proven pesticide properties, but there is little public information comparing efficacy of these ingredients. This study compared 14 essential oils and essential oil constituents from the 25(b) list in insecticidal and herbicidal contact bioassays: cedar oil, cinnamon oil, citronella oil, clove oil, eugenol, garlic oil, geraniol, geranium oil, lemongrass oil, mint oil, peppermint oil, rosemary oil, thyme oil, and 2-phenethyl propionate. Their performance as single active ingredients and as pairwise combinations with one another within liquid formulations was evaluated for additive or synergistic benefits. In contact insecticidal assays using 9th instar American cockroach (Periplaneta americana) nymphs, there was a significant difference in knockdown (KD) time in response to the different essential oils tested, but no synergistic effect was observed when two essential oils were combined . There was a positive correlation of insect KD time and contact angle of co-formulants that were combined with essential oils. Cinnamon, lemongrass and rosemary oils had slow KD times (>1 minute), but were significantly enhanced when paired with the surfactant system having the lowest contact angle of 60°. The 25(b) oils that should be considered for insecticide development based on performance are clove, eugenol, geraniol, geranium, peppermint and thyme oils. The same essential oils and surfactant combinations were tested for herbicide burndown on dandelions (Taraxacum officianale) and smooth crabgrass (Digitaria ischaemum). There were significant differences in herbicidal activity of the essential oils, but again no synergistic effect was observed when two essential oils were combined. A novel discovery of synergy was made when herbicidal activity was greatly enhanced by combining essential oils with a surfactant system containing a non-herbicidal rate of sodium caprylate, a fatty acid salt. The 25(b) oils with the highest weed injury were cinnamon, citronella, eugenol, geraniol, geranium, peppermint and thyme oils. The findings of these experiments suggest that all 25(b) essential oils except garlic oil can be formulated into effective pesticides. Targeting a low contact angle surfactant system can enhance insecticidal activity of these oils, while the use of sodium caprylate can speed phytotoxic symptoms when used as herbicides.
Advisors/Committee Members: Gardner, David.
Subjects: Agriculture
Keywords: synergy, insecticide, herbicide, essential oils
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29.
Gordon, Stuart G.
Genetic Mapping and Components of Resistance to Cercospora Zeae-Maydis in Maize.
Degree: PhD, Horticulture and Crop Science, 2003, Ohio State University
► Gray leaf spot of maize (Zea mays L.), caused by Cercospora zeae-maydis…
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▼ Gray leaf spot of maize (Zea mays L.), caused by Cercospora zeae-maydis (Tehon and Daniels), can greatly reduce grain yield worldwide. This study evaluated a novel source of resistance to C. zeae-maydis in the US Corn Belt and the Republic of South Africa (RSA), linked molecular markers to resistance loci using selective genotyping, and examined the components of resistance, sporulation, lesion length and number of lesions. The resistant maize inbred, VO613Y, was crossed to the susceptible inbred, Pa405, to obtain a population of 144 F2:3 progeny lines. These lines were evaluated at Wooster, Ohio, USA, and Cedara, RSA, for resistance to C. zeae-maydis based on percent leaf area affected (PLAA). A selected F3:4 population, derived by self-pollination of resistant and susceptible F2:3 lines, was evaluated at two Ohio locations over two seasons and at Cedara. Simple sequence repeat, restriction fragment length polymorphisms and resistance gene analog molecular marker data were obtained and analyzed based on F2:3 and F3:4 PLAA means across all environments by Kruskal-Wallis and ANOVA single factor analyses and composite interval mapping. Lesion length measurement, lesion counts and lesion sporulation data were taken on 4 resistant F3:4 progeny lines, 4 susceptible F3:4 progeny lines, and the parents. Quantitative trait loci located on two chromosome arms, 2L and 4L, together explained 47% of the variance in the F2:3 generation and 55% in the F3:4 generation across environments. Spearman rank correlations demonstrated that genotypes retained their relative ranks across environments. VO613Y-derived resistance extended the incubation period, resulted in the presence of fewer lesions and shortened the length of lesions. Taken together, this resulted in a lower percent leaf area affected by gray leaf spot. VO613Y and its resistant progeny did not inhibit spore production compared to Pa405 and its susceptible progeny, but resistant maize genotypes should contain fewer lesions capable of producing spores. The total number of spores produced on resistant maize genotypes should therefore be less than that produced on susceptible ones. These results indicate that VO613Y possesses QTL that may be introgressed into elite maize lines and deployed effectively in both southern Africa and the US Corn Belt.
Advisors/Committee Members: Pratt, Richard C.
Keywords: maize; disease resistance; genetic mapping; gray leaf spot
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30.
Grant, Trudi NL.
Characterization of Cold and Short Day Acclimation in Grape Genotypes of Contrasting Freezing Tolerance.
Degree: PhD, Horticulture and Crop Science, 2012, Ohio State University
► Grapes are temperate crops, frequently damaged by freezing temperatures. The economic losses…
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▼ Grapes are temperate crops, frequently damaged by freezing temperatures. The economic losses that result from freezing injury are major problems for grape and wine industries in cold regions. Our central hypothesis is that soluble sugars in grape tissues provides increased freezing tolerance (FT) and the larger sugar, raffinose, accumulates earlier and to higher amounts in cold-tolerant than in cold-sensitive cultivars in response to cold temperature and short-day (SD) photoperiod. The central objective of this dissertation was to characterize the morphological, physiological and biochemical changes in response to cold acclimation (CA) and SD photoperiod. The specific objectives were to: 1) characterize the morphological, physiological and biochemical changes induced by low temperature in cold-tolerant and cold-sensitive Vitis species under controlled conditions; 2) characterize the morphological, physiological and biochemical changes induced by SD photoperiod in cold-tolerant and cold-sensitive Vitis species under controlled conditions and 3) characterize the morphological, physiological and biochemical changes induced by low temperature and SD photoperiod in cold-tolerant and cold-sensitive Vitis species under field conditions. In response to temperature under controlled environs, grape (Vitis spp) cultivars ‘Frontenac’, ‘Couderc 3309’, ‘Concord’, ‘Cabernet Franc’, ‘Traminette’ and ‘Seyval’ were evaluated. Shoot growth slowed under cold temperature regimes in all cultivars except ‘Concord’. Under the non-acclimating temperature regime, raffinose concentrations were low and similar among cultivars, whereas under CA temperature regimes raffinose accumulation was generally higher and cold-tolerant cultivars accumulated higher concentrations than did cold-sensitive cultivars. Basal leaves and buds accumulated the most raffinose. In evaluating responses to SD, experiments were conducted in greenhouse using ‘Cabernet Franc’, ‘Couderc 3309’ and ‘Concord’ cultivars. Shoot growth slowed under SD photoperiod in all cultivars. There was also increased periderm formation, endodormancy induction and increased FT. ‘Concord’ was the first cultivar to initiate these changes in response to SD followed by ‘Couderc-3309’ then ‘Cabernet franc’. Under LD, raffinose concentrations were low and similar among cultivars, whereas under SD, raffinose accumulation was higher and cold-tolerant cultivars ‘Couderc-3309’ and ‘Concord’ accumulated higher concentrations than the cold-sensitive cultivar ‘Cabernet franc’. In the field study we evaluated ‘Couderc 3309’, ‘Concord’ and ‘Cabernet Franc’ and characterized changes in FT and soluble sugar concentrations during the dormant season for two years. Generally basal buds were more FT than middle buds, which were more tolerant than apical buds. The cold-tolerant cultivars ‘Couderc 3309’ and ‘Concord’ had the lowest LT50 compared to the cold-sensitive ‘Cabernet Franc’. There was variation in leaf sugar concentration but leaf raffinose content showed cultivar dependent response associated with early acclimation. Cold-tolerant cultivars showed early responses to SD before low temperatures. In buds, among all sugars, fructose, glucose, sucrose, raffinose and stachyose concentrations had strong correlations with LT50. Basal buds accumulated the most raffinose. Raffinose accumulation was also two to three times higher in the cold-tolerant cultivars than in cold-sensitive. These results suggest that raffinose might be an early step in CA that coincides with early development of FT and can be used as a screening tool for breeding cold-tolerant genotypes and a target for improving FT via gene transfer.
Advisors/Committee Members: Dami, Imed.
Subjects: Agriculture; Anatomy and Physiology; Horticulture; Plant Biology
Keywords: grape; Vitis; buds; cold acclimation; leaf; raffinose; freezing tolerance; dormancy
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