Master of Science, The Ohio State University, 2015, Horticulture and Crop Science

Begonia is one of the most speciose genera of angiosperms, with over 1500 species distributed throughout tropical and subtropical regions; it is also a very important ornamental group of plants displaying a high degree of morphological diversity. This genus is a priority for conservation and germplasm development at the Ornamental Plant Germplasm Center located at The Ohio State University, which currently holds approximately 200 accessions, maintained primarily as clonal plants. In an effort to expand germplasm work in seed storage of Begonia, and in response to a scarcity of published information about begonia seed biology we initiated a project to develop baseline information about germination, dormancy, and stress tolerance of begonia seeds. Because of the extremely small size of begonia seeds (ca. 200 µm) I adapted germination and viability testing protocols typical of Arabidopsis research, to develop relatively efficient quantitative protocols for seed studies. Using this methodology seeds can be routinely germinated on 1% agar plates at 25°C and 16 hours light. To examine the variation in seed characteristics among Begonia accessions in the collection, I selected six species from diverse environments and from different sections of the genus for which we had abundant seed and compared their germination patterns in response to temperature and light, tolerance to high humidity/high temperature stress, and dormancy. I have determined that begonia seeds are desiccation-tolerant (orthodox), require light for germination (photoblastic), germinate under a wide range of temperatures, and mostly appear to lack any strong dormancy — depending on species, and are tolerant of various level(s) of stress. I found that Begonia ulmifolia, B. fischeri, and B. dregei are tolerant to high levels of stress (120 hours at 41°C) whereas B. boliviensis, B. grandis subsp. evansiana and B. subvillosa are less so. In addition, B. dregei appears to have some dormancy, which was observ (open full item for complete abstract)

Committee: Pablo Jourdan (Advisor); Mark Tebbitt (Committee Member); Mark Bennett (Committee Member); Claudio Pasian (Committee Member) Subjects: Agriculture; Experiments; Horticulture; Plant Biology; Plant Sciences

Master of Science, The Ohio State University, 1972, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1973, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2008, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1963, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy (PhD), Ohio University, 2024, Plant Biology (Arts and Sciences)

Plants encounter various biotic and abiotic stresses daily and have developed defense mechanisms to overcome these challenges. One key system involved in these defense mechanisms is the ubiquitin (Ub)-26S proteasome system (UPS), which targets malfunctioning proteins for degradation through Ub-tagged proteasomal pathways. The E3 ligases, specifically S-phase kinase-associated protein 1 (SKP1), Cullin 1 (CUL1), and F-box (SCF) complexes, play crucial roles in this process by recognizing and tagging specific protein substrates. Arabidopsis thaliana, with over 700 F-box proteins, has the largest group of E3 ligases, yet only 5% have been functionally characterized. Phylogenetic relationships among 111 plant species have identified four clusters of F-box genes, including a cluster with more conserved F-boxes, referred to as core Arabidopsis F-box (CAF) genes. Given that CAF genes have more known functions compared to other clusters, this dissertation hypothesizes significant potential for discovering new functions among the uncharacterized F-boxes within this group. Considering the evolutionary conservation of most CAFs, I adopted a genetic approach to investigate the roles of CAFs during seed germination and seed development. To address the challenges posed by functional redundancy of duplicated CAF genes and the lethality associated with constitutive F-box overexpression in transgenic plants, I created a library of inducible overexpression lines for 40 CAF genes, many of which lacked known biological functions. By systematically examining the effects of conditional overexpression of these 40 CAFs, I found that CAF overexpression during seed germination and seed development can positively or negatively regulate radicle rupture growth, thus controlling the germination process. Specifically, I identified 24 CAFs that enhance radicle rupture and two that inhibited it by interfering with abscisic acid (ABA)-mediated germination suppression. Induction of CAFs during seed (open full item for complete abstract)

Committee: Zhihua Hua (Advisor); Yang Li (Committee Member); John Schenk (Committee Member); Morgan Vis (Committee Member) Subjects: Biology; Genetics; Molecular Biology; Plant Biology; Plant Sciences

MS, Kent State University, 2022, College of Architecture and Environmental Design

Increasing human population density in cities leads to population decline in local native plant communities. To address this condition, roofs designed to host native species offer a solution for restoring native local plant communities. Although most roof environments use engineered growing media for vegetation, a potentially more sustainable approach would be using a combination of local soils and adaptive seeds to better mimic natural habitats that may assist in creating abiotic and biotic conditions that enable plant development (Best et al. 2015; Coffman, 2009). To further an understanding of seeding rooftop environments, a field study assessing germination was conducted on two locally sourced substrates at the Lakefront Dune Roof (Lake Erie Coast, Cleveland, Ohio). The germination rates of two warm-season native species hand-seeded into two locally sourced substrates (beach stone and local sand) was observed from May 14th to August 21st, 2021. Doellingeria umbellata is a wildflower native to wet sandy prairies in Canada and the eastern region of the United States and Sporobolus compositus is a perennial grass native to dry prairies along the eastern region of the United States. Germination was recorded in four experimental treatments (4 m2): Treatment A contains thick local sand, Treatment B contains thick beach material, Treatment C contains thin local sand, and Treatment D contains thin beach material. Each treatment has varying slopes and substrate depths due to the assembly of the roof. Results show that local sand was the more productive substrate for S. compositus growth which showed a marginal germination rate in Treatment A 25.8% and Treatment C 33.2%. D. umbellata had less productive germination rates in local sand, with Treatment A 0.05% and Treatment C 0.06%, which were lower germination rates than S. compositus. I also found that beach stone was less effective at supporting S. compositus and D. umbellata combined, with the highest germination rates (open full item for complete abstract)

Committee: Reid Coffman (Advisor); Diane Davis-Sikora (Committee Member); David Ward (Committee Member) Subjects: Architectural; Architecture; Conservation; Design; Ecology; Environmental Science; Horticulture; Landscape Architecture; Plant Sciences; Soil Sciences; Wildlife Conservation

Bachelor of Science, Wittenberg University, 2020, Biology

In utilizing native plant species, communities can maintain a healthy ecosystem and biodiversity, as well as formulating a cost effective method of landscaping that, over time, can be relatively self-sufficient. College campuses, allowing for small, condensed garden areas, are prime locations for native plant populations to form and grow. While forming such populations can be costly at first, this study aims to analyze the best methods for minimizing cost by utilizing already present resources on campuses. Taking place at Wittenberg University, the study explores germination techniques on varied plant species to determine best practices for growing native plants from preexisting generations.

Committee: Amber Burgett (Advisor); Sheryl Cunningham (Committee Member); Richard Phillips (Committee Member) Subjects: Biology; Botany; Ecology; Environmental Science; Landscaping; Plant Biology; Plant Propagation; Plant Sciences

Doctor of Philosophy (PhD), Ohio University, 2020, Molecular and Cellular Biology (Arts and Sciences)

Arabinogalactan-proteins (AGPs) are a diverse family of plant hydroxyproline-rich glycoproteins implicated to function in a number of physiological processes including growth, development, cellular signaling, somatic embryogenesis, programmed cell death, and wounding. AGPs are known for the abundance of sugars present on their molecular surface. Addition of the various sugars to AGPs requires the action of numerous distinct enzymes called glycosyltransferases (GTs). Glucuronic acid (GlcA), which is the only negatively charged sugar on AGPs, is added by the action of three glucuronic acid transferases (GLCATs), namely GLCAT14A, GLCAT14B, and GLCAT14C. Hydroxyproline-Galactosyltransferases (GALTs) are responsible for initiating sugar addition to AGPs by adding galactose (Gal) to hydroxyproline residues in the AGP core protein. To date, eight GALTs, namely GALT2-6 and Hyp-O-galactosyltransferases 1-3 (HPGTs 1-3) have been identified. To overcome gene redundancy within these two GT families, I applied a cutting-edge clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9 ) gene multiplexing approach to produce higher order genetic mutants (i.e., mutants with multiple gene family members being mutated). Seven CRISPR mutants were generated including glcat14b, glcat14c, glcat14a glcat14b, glcat14b glcat14c, and glcat14a glcat14b glcat14c for the GLCAT gene family and galt3 galt4 galt6 and galt2 galt3 galt4 galt5 galt6 for the GALT gene family. These CRISPR mutants along with two existing T-DNA mutants, namely galt2 galt5 and hpgt1 hpgt2 hpgt3, were subjected to extensive biochemical and physiological phenotypic characterization. Biochemical analysis of the glcat mutants revealed that the double and triple mutants generally had small increases of Ara and Gal and concomitant reductions of GlcA, particularly in the glcat14a glcat14b and glcat14a glcat14b glcat14c mutants. Moreover, all the glcat mutants displayed significant reducti (open full item for complete abstract)

Committee: Allan Showalter (Advisor) Subjects: Biochemistry; Genetics; Molecular Biology; Plant Biology

Master of Science (MS), Ohio University, 2019, Plant Biology (Arts and Sciences)

Under future climate change, plant species are expected to shift their ranges in response to increasing temperatures and altered precipitation patterns. As seeds represent the single opportunity for plants to move, predicting potential range shifts requires an understanding about the relationship between the environment and reproduction. While total seed production is clearly important, seed quality is equally as critical and often overlooked. If a seed is low quality the likelihood of germination and successful recruitment decreases. Thus, to quantify how environmental variation affects seed quality and quantity, the reproductive output of red maple (Acer rubrum) was measured along an elevation gradient in the Monongahela National Forest, WV. In spring of 2018, 44 seeding trees were identified, and another 44 non-seeding trees were randomly selected for comparison. For each tree, a variety of individual-level characteristics were measured (i.e., DBH, canopy area, tree cores). Seed traps were placed under seed-bearing trees to collect samaras and quantify total seed production. Then, a random subsample of the collected seeds from each tree was micro-CT scanned to determine embryo volume, photographed for morphology measurements, and used for germination trials. The results showed that trees with larger canopy volumes were the most likely to produce seed. However, the number of seeds produced was negatively affected by frost events during flower and stand density. The trees with the most seeds also showed reduced growth (i.e., basal area increments) in the past 3 years. The likelihood of embryo presence increased with lower growth rates in the past 5 years, while embryo size increased with height, smaller DBH, and in areas dominated by hemlock. Both larger embryo volume and larger overall seed size increased the likelihood of germination. The results of my thesis highlight the importance of examining seed quality in addition to seed quantity for a more complete repre (open full item for complete abstract)

Committee: Rebecca Snell Dr. (Advisor); Jared DeForest Dr. (Committee Member); Brian McCarthy Dr. (Committee Member); Melissa Thomas-Van Gundy Dr. (Committee Member) Subjects: Botany; Conservation; Ecology; Plant Biology

Doctor of Philosophy, The Ohio State University, 2018, Evolution, Ecology and Organismal Biology

Intentional and unintentional species introductions have led to biological invasions with impacts on native ecosystems worldwide. This problem has motivated decades of research on the species traits and environmental conditions that lead to biological invasions. Despite these efforts, consistently predictive principles to explain invasions remain elusive. In the following chapters, I report on research of native and invasive congener species which differ in their abundance but share a similar evolutionary history. Comparing native and invasive congeners with each other, and with a more phylogenetically distant invasive species, facilitates distinguishing traits associated with invasions from those associated with phylogenetic similarity. Specifically, I examined variation in native Lonicera candensis, invasive Lonicera maackii, and invasive Rosa multiflora relative to the processes of germination, competitive interactions, and species establishment. I found that phylogenetic similarity was a better predictor of species responses than native or introduced status. In a growth chamber experiment with controlled temperature and photoperiod regimes, native and introduced Lonicera both had higher germination rates than introduced R. multiflora, but the Lonicera congeners differed in their timing of germination response. In a greenhouse experiment, invasive L. maackii was not strongly affected by intraspecific or interspecific competition, and its response to competition with R. multiflora was similar to its response in the field. In the field experiment, establishment patterns of native and introduced Lonicera were more similar to each other than they were to R. multiflora establishment. These studies indicate that introduced L. maackii behaves more similarly to its native congener than a less closely related introduced species. These results provide insight into the factors that contribute to the invasiveness of L. maackii. In particular, the relatively rapid germi (open full item for complete abstract)

Committee: Maria Miriti Ph.D. (Advisor); Karen Goodell Ph.D. (Committee Member); Kristin Mercer Ph.D. (Committee Member) Subjects: Ecology

Doctor of Philosophy, The Ohio State University, 1952, Graduate School

Committee: Not Provided (Other) Subjects: Biology

Doctor of Philosophy, Miami University, 2016, Biology

Chapter One is an introduction of the whole dissertation. I described the background information about current studies on poly(A) factors and poly(A) tail length in animals, plants and yeast. In Chapter Two we used a Minigene containing RNAi-induced phytoene desaturase (PDS) silencing structure, and a strong polyadenylation signal to select polyadenylation mutants. Four potential poly(A) factor mutants with different phenotypes were generated. In Chapter Three, we designed a novel protocol to accurately measure poly(A) tail lengths by taking advantage of a new DNA sequencing platform by Pacific Biosciences (PacBio) Inc. The authenticity of poly(A) tail length was further confirmed with Sanger sequencing by randomly picking three genes with varied poly(A) tail lengths for comparison. The results suggested that the protocol could accurately measure poly(A) tail length at a transcriptome scale. In Chapter Four we explored the role of poly(A) tail length during seed germination by using the novel protocol we designed. Based on poly(A) tail length and re-polyadenylation time, 10 stored transcripts with short poly(A) tails were identified as potential regulators of seed germination in Arabidopsis. They could be classified into 5 groups by re-polyadenylation times in germination phases. In Chapter Five, the functions of the poly(A) tail length in response to heat stress were studied. Experiments with both gradual and abrupt heat stress treatments showed that two different re-polyadenylation patterns existed among 14 transcripts. One of them was independent of heat treatment regime. The other re-polyadenylation pattern was limited to severity of heat shock. Each of them covers seven transcripts. In Chapter Six, I conclude the finding of my current studies and give perspectives for the research directions of poly(A) factors and poly(A) tail length.

Committee: Quinn li (Advisor) Subjects: Biology

Master of Science, The Ohio State University, 2013, Horticulture and Crop Science

Grafting is a technique that has been used for fruit trees and vine crops for thousand years. Grafting to rootstocks is becoming popular in annual vegetable production to control soil-borne diseases, replace fumigation, increase yield, increase tolerance to abiotic stress, and impart vigor. Previous research indicates that inconsistent seed quality and lack of information about rootstock-scion compatibility affect the efficiency of grafting, raises cost, and inhibits adoption of the technology. The goals of this research were to address limitations in seed quality and graft efficiency. The specific objectives were: a) evaluate genetic and environmental factors affecting quality of seed in hybrids derived from interspecific crosses, b) improve grafting success through use of adhesives, and c) determine the genetic basis of graft failure between rootstock and scion. Tomato is a model for grafting annual vegetables due to the importance of the crop and the extensive genetic resources available. To assess the potential to select for improved seed quality, experimental rootstocks were developed through pollination of cultivated (Solanum lycopersicum L.) parental lines as female parents and 11 accessions of wild species as male parents. Seed quality was evaluated based on seed size (weight) and total germinability for each hybrid produced. Maternal effects and environment determined fruit set. Specific genotype combinations and environment determined seed yield. Seed size was mainly affected by genetic components, while seed germination was affected by both genetics and environmental factors. Seed size can be used as selection criterion in breeding program for early selection of rootstock seed quality. To improve graft success, nine different tomato rootstocks were grafted using the traditional tube method of grafting and using adhesives. Despite wide variation across rootstock genotypes and grafting environment, grafting using adhesives resulted in higher grafting suc (open full item for complete abstract)

Committee: David Francis M. Dr. (Advisor); Pablo Jourdan Dr. (Committee Member); Matthew Kleinhenz Dr. (Committee Member) Subjects: Agriculture; Agronomy; Horticulture; Plant Sciences

PhD, University of Cincinnati, 2011, Arts and Sciences: Biological Sciences

Two of the most prevalent reasons cited for the decrease in species abundance are the loss and modification of habitat and the impact from invasive species. Riparian species face both of these challenges, being in a habitat that experiences abundant water flow modifications and experiencing a degree of disturbance which is often desired by invasive species. As a result, riparian habitat contains high levels of biodiversity, and also a high frequency of rare species. Therefore, the goal of my research was to identify genetic and reproductive factors that may be hindering population growth of rare riparian species. Spiraea virginiana can be classified as a characteristic riparian shrub, is considered rare throughout its natural range, and it is suggested to be negatively impacted by competition with the invasive S. japonica. Using this study species, I examined the extent of both clonal growth and sexual reproduction, and seed germination potential using field and laboratory methods. Genetic analyses show that S. virginiana is highly clonal and populations are isolated from one another. Genetic data also indicate that S. virginiana is likely to have been rare for an extended time period rather than recently so. Possibly as a consequence of long-term isolation, sexual reproduction is minimal and there is evidence to suggest that the self-incompatibility system is breaking down. When sexual reproduction does occur and seeds are produced, their viability and germination rates are low, being significantly lower than those of S. japonica. I conclude that the prolonged survival of S. virginiana has been the result of prolific clonal propagation. Although clonality allows the species to persist and expand, it greatly diminishes the adaptive potential of the species. The lack of mates in a self-incompatible system, or the ability to self, combined with low germination rate also contributes to the rarity of this species. Since many riparian species are both clonal and self-inc (open full item for complete abstract)

Committee: Theresa Culley PhD (Committee Chair); Sarena Selbo MS (Committee Member); Stephen Matter PhD (Committee Member); Eric Maurer PhD (Committee Member); Steven Rogstad PhD (Committee Member) Subjects: Botany

PhD, University of Cincinnati, 2005, Medicine : Pathobiology and Molecular Medicine

Conidial germination and growth by apical extension are two processes required for the initiation and progression of disease by the opportunistic pathogen Aspergillus fumigatus. The Ras family of GTPase proteins has been shown to control morphogenesis in many organisms, including several species of pathogenic fungi. Therefore, we sought to determine the requirements for Ras proteins in conidial germination and hyphal develolpment of A. fumigatus. Previously, only one homolog, rasA, had been identified, but nothing is known of its role in growth and development. We have identified a second homolog, rasB, which characterizes a new subclass of Ras genes, found only in fungi that undergo hyphal growth. Unique to the rasB homologs is a conserved amino acid domain found just upstream of the third GTP/GDP binding region. To gain insight into the roles played by RasB in A. fumigatus, dominant active (DA), dominant negative (DN) and deletion mutations were constructed for both Ras homologs. DArasB expression led to reduced conidiation. Expression of DNrasB slightly delayed the initiation of germination and caused the development of conidiophores in submerged culture, an abnormal event in A. fumigatus. Deletion of A. fumigatus rasB caused decreased germination and growth rates but no significant change in total biomass after 24 hours of growth. Deletion of rasB also created an irregular hyphal morphology characterized by increased branching. Expression of rasBΔ113-135, a mutant lacking the conserved rasB internal amino acid insertion, did not complement the deletion phenotype. Virulence of the rasB deletion strain was also reduced, as mice infected with this strain exhibited ~70% survival compared to ~10% with wild type and reconstituted strains. In contrast, DArasA expression led to reduced conidiation, malformed conidiophores, and altered mitotic progression. Expression of DNrasA caused a significant reduction in the rate of conidial germination, without further altering de (open full item for complete abstract)

Committee: Dr. Judith Rhodes (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2012, Horticulture and Crop Science

The increase of ultraviolet (UV) light levels in the northern hemisphere raises the spectre of possible problems for turfgrass plants due to long term exposure. Cool season turfgrasses which are susceptible to photoinhibition may suffer from a loss of productivity and growth, reducing their ability to sequester carbon. The effect on germination, plant responses in relation to UV absorbing compounds and how turfgrasses were evaluated for loss of quality with regards to linking new technology to visual ratings have had no or limited research. Enhancing the percentage of Kentucky bluegrass (Poa pratensis L.) seed germination and speed could benefit establishment of the grass in a greater range of environmental and geographical conditions. Potential for the use of ultraviolet light to enhance Kentucky bluegrass seed germination exists through exposure to UV light. The effect of ultraviolet light may be lost with seed age. In altering wavelength exposure, there may be an opportunity to enhance the effect. In measuring turf quality, traditionally human measurement has been the standard method for both color and cover. Color, in particular, is thought to be controlled by pigment changes. In evaluating a total of 51 cultivars of tall fescue (Schedenorus phoenix Scop. Holub), perennial ryegrass (Lolium perenne L.) creeping bentgrass (Agrostis stolonifera L.) cv. ‘Penncross' and ‘L-93' it was found that nitrogen content is most crucial in color measurements. Reflective measurements did not correlate with nitrogen or chlorophyll content. Extract measurements had stronger correlation with nitrogen content than pigmentation concentration. Current reflective measurement equipment may not be closely linked to visual rating of turfgrass color possibly due to variation in leaf surfaces. There is a difference in response to UV light among grass species. Creeping bentgrass ‘L-93' produced increasing anthocyanin in response to UV light. The characterization of Cyanidin – 3 – O – gluc (open full item for complete abstract)

Committee: David S. Gardner PhD (Advisor); James D. Metzger PhD (Committee Member); Tom K. Danneberger PhD (Committee Member); Luis E. Rodriguez-Saona PhD (Committee Member) Subjects: Horticulture

Doctor of Philosophy, The Ohio State University, 2011, Horticulture and Crop Science

TZF proteins are characterized by two CCCH Zinc Finger motifs arranged in tandem. In animals, TZFs can localize to specialized cytoplasmic RNA processing centers (Processing Bodies and Stress Granules), and control a variety of cellular processes via the regulation of gene expression at post-transcriptional level. The best characterized TZF so far is human tristetraproline (hTTP). hTTP can regulate mRNA stability by binding to the AU-rich elements in the 3' untranslated region of target mRNAs and inducing rapid RNA turnover through the recruitment and activation of RNA decay machinery. While TZF functions have been revealed in animals, the functions of plant TZFs remain largely unknown. In Arabidopsis thaliana, there are 11 TZF genes (AtTZF) that contain a TZF motif variant unique to plants. Using a variety of molecular, biochemical, and in silico techniques. I investigated the possible roles for AtTZF function in plants, and compared my results to reports from other eukaryotic TZF proteins. Similar to the TZF genes in animals, I show that AtTZFs in plants can co-localize with, DCP2, AGO1, and XRN4 mRNA processing factors in cytoplasmic foci that resemble plant Processing Bodies and Stress Granules. However, unlike hTTP that can bind RNA through its central TZF domain, AtTZF1 affinity for RNA and DNA requires an additional upstream region characterized by a conserved motif unique to plant TZFs. In silico structural analysis of the AtTZF1 zinc finger motif reveals further differences between animal and plant TZFs suggesting that AtTZFs may bind RNA targets different from those of animal TZFs. Consistent with these differences in structure, I show that AtTZF1 does not bind to the hTTP consensus RNA binding sites. Though the precise molecular mechanism underlying AtTZF1's function remains unclear, I show that the expression of AtTZF1 in plants has profound effects on many aspects of ABA and GA mediated growth, development and stress responses. AtTZF1 overexpression (open full item for complete abstract)

Committee: Jyan-Chyun Jang PhD (Advisor); John Finer PhD (Advisor); Erich Grotewold PhD (Committee Member); Iris Meier PhD (Committee Member) Subjects: Plant Biology

Doctor of Philosophy, The Ohio State University, 2009, Horticulture and Crop Science

Biological invasion is a global phenomenon that has caused great damage to ecosystems as well as to the economy. Many factors have been found to be associated with and contributed to the success of invasive species. Phenotypic plasticity, the ability of a plant genotype to respond to different environmental conditions by producing different phenotypes, might play an important role in biological invasion, but more empirical studies are needed before a general pattern emerges that can be used in predicting the invasive potential of a species. This dissertation describes studies that investigated the role of phenotypic plasticity in the success of invasive plants using three dandelion species (Taraxacum, Asteraceae) as model system. Taraxacum officinale is an aggressive weed, while T. laevigatum only has limited distribution in North America. T. kok-saghyz has been introduced as a potential crop, but its potential invasiveness is unknown. In three major experiments, I tested the hypothesis that the invasive T. officinale and non-invasive T. laevigatum will exhibit different phenotypic plasticity in germination, growth, and reproduction in various lab, greenhouse, and field environments. I also proposed that their responses in stressful and favorable conditions could be used to assess the invasive potential of T. kok-saghyz. The results revealed complicated responses of the three species in various environments. The invasive T. officinale showed higher germination in high alternating temperature, and accumulated more biomass than the non-invasive T. laevigatum in favorable greenhouse conditions. Surprisingly, T. laevigatum germinated better than T. officinale in other stressful environments (dark, low water potential, long aging period), and also exhibited higher fecundity in favorable greenhouse conditions. In field experiments, however, the performance of T. officinale was overwhelmingly better than T. laevigatum, which suffered very high mortality and failed to surv (open full item for complete abstract)

Committee: John Cardina (Advisor); Kent Harrison (Committee Member); Maria Miriti (Committee Member); Emilie Regnier (Committee Member) Subjects: Agriculture; Agronomy; Biology; Botany; Ecology; Environmental Science; Horticulture

Doctor of Philosophy, The Ohio State University, 2005, Horticulture and Crop Science

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 techniqu (open full item for complete abstract)

Committee: Pablo Jourdan (Advisor) Subjects: