Plant Breeding and Genetics Commons^™

Aronia Mitschurinii: Solving A Horticultural Enigma, Peter J. Leonard

Master's Theses

Aronia (Medik.), commonly known as chokeberry, is a taxonomically misunderstood genus currently experiencing a renaissance in North America as both an ornamental and fruit crop. Three species of chokeberry are commonly accepted as native in North America: A. arbutifolia (L.) Pers. red chokeberry; A. melanocarpa (Michx.) Elliot, black chokeberry; and A. prunifolia (Marshall) Rehder, or purple chokeberry. In Europe a fourth species of human origin is recognized as Aronia mitschurinii (A.K.Skvortsov & Maitul.), or cultivated, black-fruited Aronia. It is widely speculated that this genotype originated in the early 20^th century with Russian pomologist Ivan Michurin, as the product …

Herbicide-Resistant Risk Assessment: Response Of Common Nebraska Weeds To Dicamba Dose, Roberto J. Crespo

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Dicamba-resistant soybeans are being developed to provide an additional herbicide mechanism of action that can be used in soybean, and to provide a tool to help manage or mitigate the evolution of other herbicide-resistant weed populations. The objectives of this thesis were to assess the risk of common Nebraska weeds developing resistance to dicamba, quantify baseline dose-response to dicamba of high-risk weed species, and survey the variability in dicamba dose-response among populations of those species. Twenty-five weed scientists were asked to estimate the risk likelihood of ten weed species evolving resistance to dicamba following the commercialization of dicamba-resistant soybean. Palmer …

Oral Presentation: Plant Genes And Drought Tolerance, Norris Lam

Festival of Communities: UG Symposium (Posters)

Research has shown that a gene from C3 xerophyte Larrea tridentata (creosote bush), LtWRKY21, is involved in pathways governing creosote bush’s high tolerance to environmental stress. By understanding the way in which creosote bush adapts to drought, crop plants can be engineered to be more drought tolerant during times of imminent global climate change. To study the underlying mechanisms of creosote bush drought response, the LtWRKY21 gene was mobilized into the model organism Arabidopsis thaliana. Chlorophyll degradation, cellular electrolyte leakage, and water content in leaves will serve as indicators of drought tolerance in LtWRKY21-transgenic A. thaliana after treatment in chemically …

Assessing Genetic Differentiation Among Populations Of The Invasive Plant Impatiens Glandulifera In Maine, Jordan R. Schoonover

Honors Theses

The annual herbaceous plant Impatiens glandulifera Royle is native to the Himalayas and is a significant invasive species in Europe. In the past century, it was introduced to the United States, where it has become established in 12 states. This study evaluated genetic differentiation among four Maine populations, to address a theory that posits hybridization of distinct lineages as a trigger for invasiveness. Regions of microsatellite repeats were evaluated at two polymorphic loci for 41 plants sampled from the four populations. A striking finding was that the observed heterozygosity was substantially higher than the heterozygosity expected from random combination of …

Letter From The Dean, Lalit Verma

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

No abstract provided.

Using A Diverse Seed Mix To Establish Native Plants On A Sonoran Desert Burn, Scott R. Abella, John L. Gunn, Mark L. Daniels, Judith D. Springer, Susan E. Nyoka

Fire Science Presentations

• Revegetating burned areas is a formidable challenge facing resource managers in southwestern United States arid lands.
• Natural revegetation of desert burns by native species may be slow, or dominated by exotic annual grasses that perpetuate a frequent-fire regime.
• Resource managers may have several reasons for actively revegetating burns with native species, such as for providing competition with exotic species, minimizing soil erosion and dust pollution, and improving aesthetics.
• The use of native species in revegetation has been limited by a lack of available seed and by findings that native desert species are difficult to establish (e.g., Bainbridge and Virginia 1990, …

The Pollination Biology And Mating System Of A Peripheral Population Of Witheringia Solanacea (Solanaceae), Timothy Miller

Honors Theses

Pollinator visitation rates over the life of a flower are determined by pollinator abundance and floral longevity. If flowers are not visited frequently enough, pollen limitation may occur, favoring the evolution of self-compatibility (SC). In plant species with varying SC levels, central populations often are self-incompatible (SI) and peripheral populations are SC. Witheringia solanacea (Solanaceae) is a species that follows this trend with the exception of one population in the Monteverde Cloud Forest Reserve, which is peripheral yet SI. I investigated this population using multiple techniques including floral bagging, pollinator observations, microsatellite analysis, and floral longevity manipulations. My results confirmed …

Seeding Effectiveness And Natural Regeneration Of Mojave Desert Plant Communities After 2005-2006 Wildland Fires, E. Cayenne Engel, Scott R. Abella, Christina L. Lund

Fire Science Presentations

1) Assessment of BLM seeding effectiveness in mid-elevation burn where pre-burn plant communities were dominated by blackbrush, Joshua trees, and creosote.

2) Patterns driving fire recovery at the landscape scale:

• Link initial vegetation, environment, and soils
• Are there patterns that can be gleaned that can then be applied to management prescriptions?

Reproductive Ecology Of Two Common Woody Species, Juniperus Sabina And Artemisia Santolinifolia, In Mountain Steppes Of Southern Mongolia, Katrin Ronnenberg

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

The present study describes the reproductive ecology of the prostrate shrub Juniperus sabina and the dwarf shrub Artemisia santolinifolia in dry mountain steppes of southern Mongolia. Whereas stands of the juniper are located at the drought limit of the genus’ distributional range, the genus Artemisia is typical of central Asian drylands. Both species produce large numbers of reproductive organs. For Juniperus sabina, however, only 2.5% of the morphologically intact seeds were found to be viable. Correspondingly, neither seedlings nor saplings were found in the field, and recruitment by reseeding happens at most rarely under the present climatic conditions.

Instead, …

Clone Size Of Andropogon Gerardii Vitman (Big Bluestem) At Konza Prairie, Kansas, Kathleen H. Keeler, Charles F. Williams, Linda S. Vescio

School of Biological Sciences: Faculty Publications

Clone size of plants of Andropogon gerardii from Konza Prairie Biological Station, Manhattan, Kansas was estimated from spatial patterns of genetic variation, using proteins detected by starch gel electrophoresis and DNA content (ploidy) measured by flow cytometry. Unique multi-locus protein banding patterns and differences in ploidy were used to exclude plants as members of the same clone. Individual clones averaged about 2 m in diameter and areas of prairie of 100 m² were calculated to contain an average of 31.8 genetic individuals.

A Lighter Shade Of Green: Reproducing Nature In Central Florida, Kevin Archer

All Faculty Scholarship for the School of Graduate Studies and Research

No abstract provided.

Australian Genetic Resources Of Trifolium And Ornithopus Species, Richard Snowball, Kevin Foster, Bill Collins

Journal of the Department of Agriculture, Western Australia, Series 4

The introduction of improved pasture legumes into the cereal growing areas of southern Australia changed the face of our agricultural systems.

Subterranean clover was the first pasture legume to have a major impact, and the first varieties were available commercially in the 1930s. Since then, many varieties have been released, leading to the most recent release of Denmark, Gou/bum and Leura in 1992.

The development of burr, barrel and murex medics also had an impact on the pasture production of less acid heavy soils. Yellow serradella is still being developed for the more acid sandy soils.

This development of improved …

Can Genetically Engineered Crops Become Weeds?, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

There are significant differences if the distribution of weedy characteristics among weeds, normal plants, and crops. The world’s most serious weeds possess on the average 10 or 11 of these characters, a random collection of British plants have an average seven of the traits, and crop plants only five. For the average crop to become as “weedy” as the average weed, it would need to acquire five weedy traits. Even using the unlikely assumption that those traits are single loci in which a dominant mutation would provide the weedy character, this would require the simultaneous acquisition of five gene substitutions. …

W.A. Wildflowers Are Unique, Alexander S. George

Journal of the Department of Agriculture, Western Australia, Series 4

Western Australian wildflowers are some of the most unusual and fascinating in the world. Of the 3,000-odd species growing in the southwest, about 85 per cent, grow nowhere else in the world.

Dwarf Fruit Trees, Frank Melville

Journal of the Department of Agriculture, Western Australia, Series 4

IN this country where most fruits and particularly apples and pears are grown without irrigation, heavy crops and summer stress restrict tree size.

The aim of most growers therefore, has been to grow larger trees and little interest has been shown in trees with dwarfing tendencies.

However, in countries with ideal conditions for growth, trees tend to grow too big and become uneconomic in terms of labour costs.