Doctor of Philosophy / Department of Biology / Carolyn J. Ferguson / Morus L. (Moraceae) is a temperate and subtropical genus of ten to 15 species distributed in Asia, Africa, Europe, North, Central and South America. Despite its broad distribution and economic importance, it has received little attention from systematic botanists. Two species of this genus, the native M. rubra and the exotic M. alba, co-occur in eastern North America including the Flint Hills region of the Central Plains. In my dissertation research, I have conducted both species level and population level studies to obtain insights into the diversification of Morus. At the species level, my objectives were to re-evaluate the taxonomy and reconstruct the phylogeny of Morus. Based on herbarium and literature study as well as some field study, I recognize 13 species: eight species occurring in Asia, one in Africa and four in the New World. I used sequence data from the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA and the trnL-trnF region of the chloroplast DNA to reconstruct the evolutionary history of Morus. The phylogenies were congruent and indicate a) a monophyletic core group of Morus with two well-supported geographical clades (one containing Asian taxa and one of New World taxa); and b) that Morus, as currently circumscribed, is non-monophyletic. At the population level, I studied sex expression pattern variation between the Morus native-exotic pair in the Flint Hills region, and assessed hybridization between these species at Konza Prairie Biological Station (KPBS). Both species are subdioecious, and Flint Hills populations exhibit significantly male-biased sex ratios, with sex expression being size independent. Approximately 10% of individuals of each species changed sex annually. In the population study at KPBS, I applied randomly amplified polymorphic DNA (RAPD) markers and microsatellites. The Morus species were moderately ([Theta]II = 0.079; RAPD data) to highly differentiated genetically (F[subscript]ST = 0.233; microsatellite data). Analysis of genetic structure suggested interspecific gene flow and indicated the presence of later generation hybrids. The presence of the exotic congener may affect the existence and genetic integrity of the native species. Overall, these studies contribute to our understanding of diversity in this interesting plant study system.

Doctor of Philosophy / Department of Horticulture, Forestry, and Recreation Resources / Dale J. Bremer / Turfgrass covers 1.9% of the nation’s surface area and is the largest irrigated crop in the USA. Developed urbanized land is projected to double by 2025, which will increase turf’s environmental impact. Studies were conducted to evaluate environmental impacts by characterizing nitrogen, carbon, and water fluxes in turfgrass ecosystems. Emissions of nitrous oxide (N[subscript]2O), a major greenhouse gas and ozone depleter were measured from bermudagrass (Cynodon dactylon L. Pers. x C. transvaalensis Burtt-Davy) (bermuda), perennial ryegrass, (Lolium perenne L.) (rye), and zoysiagrass, (Zoysia japonica Steud.) (zoysia) under regional N management. In a separate study, N2O fluxes were measured from bermuda fertilized with controlled-release N fertilizers including polymer-coated and organic-N, and quick release urea. Emissions of N2O were measured using static surface chambers and gas chromatography. Zoysia, with less N requirements, had lower emissions than bermuda. Cumulative N[subscript]2O emissions were similar among N types. To measure water and carbon fluxes, a portable non-steady state chamber was designed and tested. The chamber had minimal affects to the canopy during field measurements: leak values averaged <1.5 micromol CO[subscript]2 m[superscript]-2 s[superscript]-1; average chamber pressure was 0.09 Pa ±0.01 Pa; temperature rise inside the chamber averaged 0.74C; and the chamber had 90% photosynthetically active radiation transmittance. Using the chamber, differences were detected in net photosynthesis (Pnet), gross photosynthesis (Pg), evapotranspiration (ET), canopy stomatal conductance (gc), and water use efficiency (WUE) in well-watered tall fescue (Festuca arundinacea Schreb.), Kentucky bluegrass (Poa pratensis L.) (KBG), zoysia, and bermuda. Irrigation requirements, visual quality ratings, and genetic rooting potential of 28 KBG cultivars and 2 Texas bluegrass hybrids (P. pratensis x P. arachnifera Torr.) were quantified in greenhouse and rainout facility studies. Average water applied ranged from 23.4 to 40.0 cm among cultivars. Bedazzled, Preakness, and Bartitia required less water and had higher average quality than other cultivars. Compact America and Mid-Atlantic phenotypes exhibited greatest potential for success in integrating reduced water inputs with maintenance of acceptable visual quality. Results indicated that turfgrass management could mitigate N[subscript]2O emissions and conserve water while maintaining healthy turfgrass, and the new chamber will enhance turfgrass studies by providing rapid measurements of photosynthesis.

Master of Science / Department of Biology / David C. Hartnett / Perennial grasses on tallgrass prairie primarily reproduce vegetatively via the belowground bud bank, yet the production, dynamics, and morphology of belowground buds is largely unexplored. Since the two main photosynthetic pathway guilds (C3 and C4) on tallgrass prairie vary in their aboveground phenology, their belowground phenology would also be expected to vary. Differences in bud production, development, and spatial arrangement result in different growth forms. Therefore, an extensive biweekly examination of a dominant tallgrass prairie C4 rhizomatous grass Andropogon gerardii and C3 caespitose grass Dichanthelium oligosanthes was conducted over an entire year. Andropogon gerardii and D. oligosanthes have multiple distinctive bud developmental stages. Andropogon gerardii was synchronous in its bud development and its bud bank was composed of multiple annual cohorts. The bud bank of D. oligosanthes was developmentally asynchronous and was comprised of a single bud cohort since its bud bank underwent a complete turnover in early summer. The different roles of buds in the life history of each species reflected their differences in bud longevity, quality, and dormancy. In D. oligosanthes, belowground buds enabled plant survival over the C3 summer dormant period whereas juvenile tillers overwintered during the longer winter dormant period. In contrast, A. gerardii survived its single, winter dormant period as dormant buds. The higher-order bud production observed in D. oligosanthes multiplied its tiller production potential and, along with its shortened internodes, contributed to its caespitose growth form. The rhizomatous growth form of A. gerardii resulted from its lack of higher-order bud production and its elongated internodes. Differences in production of buds per vegetative and flowering tiller were quantified in A. gerardii. Flowering tillers of A. gerardii produced larger numbers of buds per tiller and transitioned a larger proportion of their buds to tillers than did vegetative tillers. Therefore, no tradeoff between sexual and vegetative reproduction was evident. Developmental constraints likely prevented such a tradeoff. Bud bank dynamics offer insight into the control of grass population dynamics, production, and ultimately aboveground net primary production (ANPP) and will be useful in understanding the underlying mechanisms by which management practices and environmental change can alter perennial grasslands.

Light microscopy, low ionic strength solution culture and image analysis methods were used to make detailed measurements on root hair populations of different genotypes of white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.). A model of root hair population structure was developed and validated that will facilitate research on root hairs of these species. Diagrams were drawn of the root hair length and frequency on entire root systems. The distributions of root hairs on these diagrams often differed from textbook diagrams of root hairs because root hair length and frequency varied considerably along the root axis. The key issue examined was the response at species, population and genotype levels of root hair populations perturbed by aluminium and phosphate, and the implications of these responses for our understanding of the strategies adopted by plants growing in stressful environments. Demographic growth analysis gave the best understanding of the mechanisms of root hair population response to genetic variability, resource depletion and environmental perturbation. Root hair length seemed to be controlled by the individual root hair. However the number of root hairs appeared to be controlled by the root. Therefore it is the root that controls the distribution of the hairs on the root, and how this distribution is modified by perturbation. Root hair populations were shown to have strategies that were similar to their shoot system growth strategies-guerrilla for clover, phalangeal for ryegrass. The root and root hair systems, and shoot systems also demonstrated similar characteristics when the r and K strategy model was applied. At an ecosystem level, clover and ryegrass occupied the same orthogonal in the CSR (competitive-stress-ruderal) model. Therefore at a larger scale, these plants are able to coexist, but they do this by having different strategies at a species level. / Subscription resource available via Digital Dissertations only.

Light microscopy, low ionic strength solution culture and image analysis methods were used to make detailed measurements on root hair populations of different genotypes of white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.). A model of root hair population structure was developed and validated that will facilitate research on root hairs of these species. Diagrams were drawn of the root hair length and frequency on entire root systems. The distributions of root hairs on these diagrams often differed from textbook diagrams of root hairs because root hair length and frequency varied considerably along the root axis. The key issue examined was the response at species, population and genotype levels of root hair populations perturbed by aluminium and phosphate, and the implications of these responses for our understanding of the strategies adopted by plants growing in stressful environments. Demographic growth analysis gave the best understanding of the mechanisms of root hair population response to genetic variability, resource depletion and environmental perturbation. Root hair length seemed to be controlled by the individual root hair. However the number of root hairs appeared to be controlled by the root. Therefore it is the root that controls the distribution of the hairs on the root, and how this distribution is modified by perturbation. Root hair populations were shown to have strategies that were similar to their shoot system growth strategies-guerrilla for clover, phalangeal for ryegrass. The root and root hair systems, and shoot systems also demonstrated similar characteristics when the r and K strategy model was applied. At an ecosystem level, clover and ryegrass occupied the same orthogonal in the CSR (competitive-stress-ruderal) model. Therefore at a larger scale, these plants are able to coexist, but they do this by having different strategies at a species level. / Subscription resource available via Digital Dissertations only.

Light microscopy, low ionic strength solution culture and image analysis methods were used to make detailed measurements on root hair populations of different genotypes of white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.). A model of root hair population structure was developed and validated that will facilitate research on root hairs of these species. Diagrams were drawn of the root hair length and frequency on entire root systems. The distributions of root hairs on these diagrams often differed from textbook diagrams of root hairs because root hair length and frequency varied considerably along the root axis. The key issue examined was the response at species, population and genotype levels of root hair populations perturbed by aluminium and phosphate, and the implications of these responses for our understanding of the strategies adopted by plants growing in stressful environments. Demographic growth analysis gave the best understanding of the mechanisms of root hair population response to genetic variability, resource depletion and environmental perturbation. Root hair length seemed to be controlled by the individual root hair. However the number of root hairs appeared to be controlled by the root. Therefore it is the root that controls the distribution of the hairs on the root, and how this distribution is modified by perturbation. Root hair populations were shown to have strategies that were similar to their shoot system growth strategies-guerrilla for clover, phalangeal for ryegrass. The root and root hair systems, and shoot systems also demonstrated similar characteristics when the r and K strategy model was applied. At an ecosystem level, clover and ryegrass occupied the same orthogonal in the CSR (competitive-stress-ruderal) model. Therefore at a larger scale, these plants are able to coexist, but they do this by having different strategies at a species level. / Subscription resource available via Digital Dissertations only.

Light microscopy, low ionic strength solution culture and image analysis methods were used to make detailed measurements on root hair populations of different genotypes of white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.). A model of root hair population structure was developed and validated that will facilitate research on root hairs of these species. Diagrams were drawn of the root hair length and frequency on entire root systems. The distributions of root hairs on these diagrams often differed from textbook diagrams of root hairs because root hair length and frequency varied considerably along the root axis. The key issue examined was the response at species, population and genotype levels of root hair populations perturbed by aluminium and phosphate, and the implications of these responses for our understanding of the strategies adopted by plants growing in stressful environments. Demographic growth analysis gave the best understanding of the mechanisms of root hair population response to genetic variability, resource depletion and environmental perturbation. Root hair length seemed to be controlled by the individual root hair. However the number of root hairs appeared to be controlled by the root. Therefore it is the root that controls the distribution of the hairs on the root, and how this distribution is modified by perturbation. Root hair populations were shown to have strategies that were similar to their shoot system growth strategies-guerrilla for clover, phalangeal for ryegrass. The root and root hair systems, and shoot systems also demonstrated similar characteristics when the r and K strategy model was applied. At an ecosystem level, clover and ryegrass occupied the same orthogonal in the CSR (competitive-stress-ruderal) model. Therefore at a larger scale, these plants are able to coexist, but they do this by having different strategies at a species level. / Subscription resource available via Digital Dissertations only.

Light microscopy, low ionic strength solution culture and image analysis methods were used to make detailed measurements on root hair populations of different genotypes of white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.). A model of root hair population structure was developed and validated that will facilitate research on root hairs of these species. Diagrams were drawn of the root hair length and frequency on entire root systems. The distributions of root hairs on these diagrams often differed from textbook diagrams of root hairs because root hair length and frequency varied considerably along the root axis. The key issue examined was the response at species, population and genotype levels of root hair populations perturbed by aluminium and phosphate, and the implications of these responses for our understanding of the strategies adopted by plants growing in stressful environments. Demographic growth analysis gave the best understanding of the mechanisms of root hair population response to genetic variability, resource depletion and environmental perturbation. Root hair length seemed to be controlled by the individual root hair. However the number of root hairs appeared to be controlled by the root. Therefore it is the root that controls the distribution of the hairs on the root, and how this distribution is modified by perturbation. Root hair populations were shown to have strategies that were similar to their shoot system growth strategies-guerrilla for clover, phalangeal for ryegrass. The root and root hair systems, and shoot systems also demonstrated similar characteristics when the r and K strategy model was applied. At an ecosystem level, clover and ryegrass occupied the same orthogonal in the CSR (competitive-stress-ruderal) model. Therefore at a larger scale, these plants are able to coexist, but they do this by having different strategies at a species level. / Subscription resource available via Digital Dissertations only.