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Anther Appendages Of Incarvillea Trigger A Pollen-Dispensing Mechanism, Yi Han, Can Dai, Chun-Feng Yang, Qing-Feng Wang, Timothy J. Motley

Biological Sciences Faculty Publications

Background and Aims Anther appendages play diverse roles in anther dehiscence and pollen dispersal. This study aims to explore the pollen-dispensing mechanism triggered by special anther appendages in Incarvillea arguta.

Methods Field studies were conducted to record floral characteristics, pollinator visitations, and flower-pollinator interactions. Measurements of flowers and pollinators were analysed statistically. Pollen counts following a series of floral manipulations were used to evaluate pollen dispensing efficiency and function of the anther appendages.

Key Results Field observations determined that two species of Bombus (bumble-bees) were the primary pollinators of I. arguta with a mean visiting frequency of 1.42 visitations …

Determining Optimum Planting Dates For Pearl Millet For Two Contrasting Environments Using A Modelling Approach, C. M. T. Soler, N. Maman, X. Zhang, S. C. Mason, G. Hoogenboom

Department of Agronomy and Horticulture: Faculty Publications

Pearl millet [Pennisetum glaucum (L) R. Br.] is an important cereal crop in Niger, West Africa and a potential crop for the United States of America (USA). Only a few studies have been conducted in either country to identify the optimum planting dates for high and stable yields, in part because planting date experiments are resource-intensive. Crop simulation models can be an alternative research tool for determining optimum planting dates and other management practices. The objectives of the present study were to evaluate the performance of the Cropping System Simulation Model (CSM)–CERES-Millet model for two contrasting environments, including Mead, …

Floristic Records In The Platte And Loup River Bottomlands Of Platte County, Nebraska, Michael P. Gutzmer, Robert B. Kaul

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

A recent inventory of vascular plants in the Loup and Platte riverbottoms in Platte County has greatly increased knowledge of the area's flora. Of the 542 species of vascular plants now known to grow in the county, 289 were discovered after 1977, with more than 100 of those after 1990. 425 native and 117 naturalized species are known so far. Nearly 700 native and naturalized alien species are expected to occur in the county, based upon totals from nearby counties. Thus, almost 150 years after European settlement, more than 20% of the species remain unverified; of those, many are undoubtedly …

Tillage Erosion Coefficients For Selected Tillage Tools, Javier Mollinendo

Electronic Theses and Dissertations

Soil loss as a result of differential translocation of soil by tillage is widespread in regions with irregular topography. Tillage erosion models are based on field derived transport coefficients that are specific to the tillage tool being used. Variables like speed and depth of tillage can modify tillage erosion transport coefficients. Four treatments were established for this research: moldboard plow, chisel plow, tandem disk, and no-till drill. The primary research site was located in Rock County MN, 43° 39 '40.24 "N, and 96° 24' 17.25" W, with a fine-loamy, mixed, superactive, mesic Cumulic Endoaquolls (USDA, 2006). The objectives of this …

Quantitative-Genetic Variation In Morphological And Physiological Traits Within A Quaking Aspen (Populus Tremuloides) Population, Megan K. Kanaga, Ronald J. Ryel, Karen E. Mock, Michael E. Pfrender

Wildland Resources Faculty Publications

Genetic diversity within populations is an important component of adaptive evolution, and recent research has demonstrated that genetic variation within plant populations can have important ecological effects. In this study, we investigate quantitative-genetic variation in several traits within a quaking aspen (Populus tremuloides Michx.) population. A common garden experiment was planted with replicates of 13 aspen genotypes collected from wet and dry sites within a population in southern Utah, USA. Ten growth, leaf, physiological, and structural traits were measured. There were significant, heritable phenotypic differences among genotypes in every measured trait and differences in 4 of the 10 traits among …

Seasonal Adaptation Of Vegetation Color In Satellite Images, Srinivas Jakkula, Vamsi K.R. Mantena, Ramu Pedada, Yuzhong Shen, Jiang Li, Hamid R. Arabnia (Ed.)

Electrical & Computer Engineering Faculty Publications

Remote sensing techniques like NDVI (Normal Difference vegetative Index) when applied to phenological variations in aerial images, ascertained the seasonal rise and decline of photosynthetic activity in different seasons, resulting in different color tones of vegetation. The rise and fall of NDVI values decide the biological response, either the green up or brown down [1]. Vegetation in green up period appears with more vegetative vigor and during brown down period it has a dry appearance. This paper proposes a novel method that identifies vegetative patterns in satellite images and then alters vegetation color to simulate seasonal changes based on training …

Dms Air/Sea Flux And Gas Transfer Coefficients From The North Atlantic Summertime Coccolithophore Bloom, Christa Marandino, Warren J. De Bruyn, Scott Miller, Eric S. Saltzman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Dimethylsulfide (DMS) atmospheric and oceanic concentrations and eddy covariance air/sea fluxes were measured over the N. Atlantic Ocean during July 2007 from Iceland to Woods Hole, MA, USA. Seawater DMS levels north of 55 degrees N ranged from 3 to 17 nM, with variability related to the satellite-derived distributions of coccoliths and to a lesser extent, chlorophyll. For the most intense bloom region southwest of Iceland, DMS air/sea fluxes were as high as 300 mu mol m(-2) d(-1), larger than current model estimates. The observations imply that gas exchange coefficients in this region are significantly greater than those estimated using …

Lake Mead National Recreation Area Vegetation Monitoring And Analysis: Quarterly Progress Report, October 1, 2007 To December 31, 2007, Margaret N. Rees

Vegetation Monitoring

Executive Summary

• The Weed Sentry program surveyed more than 750 miles of federal lands in Clark County for invasive, exotic plant species.
• Weed Sentry also removed more than 600,000 individual invasive plants from federal
  lands. These removals represent pro-active efforts that may have forestalled large
  infestations difficult and costly to eradicate.
• In response to a request by the manager of the Fish and Wildlife Service Desert National
  Wildlife Refuge, a major effort of surveying springs for plant community composition
  and invasive plants provided unique knowledge services by the Weed Sentry program.
  No such baseline information existed for the Sheep Range. …

Joint Fire Science Program – Lake Mead National Recreation Area: Revegetating Burned Arid Lands: Identifying Successful Native Species Using Trait And Competition Analysis, Quarterly Progress Report, October 1, 2007 To December 31, 2007, Margaret N. Rees

Fire Science

The task agreement was awarded to UNLV on October 1, 2007. This report covers the period October 1, 2007 to December 31, 2007. The following activities have been conducted toward meeting or exceeding deliverables in the statement of work: hiring and project start and experimental set-up

An Assessment Of Methods For Sampling Carabid Beetles (Coleptera: Carabidae) In A Montane Rain Forest, B. A. Nyundo, J. G. Yarro

Tanzania Journal of Science

Pitfall trapping is the traditional method for sampling carabid beetles and other grounddwelling invertebrates. Tests were carried out in the Udzungwa Mountains National Park between March 1999 and July 2000. Results indicated that pitfall traps were less efficient compared to manual searching methods, both in terms of relative abundance and species richness of carabid beetles. The results are discussed in the context of biodiversity inventories in theEastern Arc Mountains.

Impact Of Small Scale Gold Mining On Soils Of The Wetland Forests In East Usambara, Tanzania, C. Kweyunga, R. B. M. Rbm Senzota

Tanzania Journal of Science

Soil pits in disturbed and natural wetland forests of East Usambara were excavated and soil profile samples collected and analysed for physical and chemical properties. Their physical and chemical characteristics were found to be sharply different from those of the surrounding hills. Differences included lack of A Horizon, water saturation, presence of very high organic matter, very low pH and hence very poor in basic cations, and low microbial activity. Nutrient recycling, especially nitrogen and phosphorus, tended to shift from mineralization to immobilization. Effects of soil disturbance on both physical and chemical characteristics of the soils were also very vivid. …

Evidence Of Ecological Speciation In Phacelia., Pamela Michele Glass

Electronic Theses and Dissertations

Phacelia purshii Buckley and P. fimbriata Micheaux are two species that are nearly morphologically indistinguishable. Seed germination experiments showed that the high elevation endemic, P. fimbriata requires lower temperatures to trigger germination. Following interspecific crosses, pollen tubes enter ovules and maternal tissue of the gynoecium matures but hybrid diploid and triploid organs fail to develop. DNA sequences from the ribosomal DNA internal transcribed region showed that P. fimbriata and P. purshii comprise a monophyletic clade but that P. fimbriata is more differentiated from related species. In contrast, P. purshii supported significantly higher levels of intraspecific polymorphism. Phacelia fimbriata and P. …

Comparison Of Compost Tea And Biological Fungicides For Control Of Early Blight In Organic Heirloom Tomato Production, Richard Kouyoumjian

All Theses

The efficacy of compost tea was evaluated and compared alone and in combination with two biofungicides Serenade Max and Sonata for control of early blight caused by the fungal pathogen Alternaria tomatophila on tomato Solanum lycopersicum (L), heirloom cultivar `Cherokee Purple'. Results of field experiments over two growing seasons indicated that compost tea provided a low level of protection against early blight. The results were variable; most likely due to dry conditions and the presence of bacterial wilt the first year and tomato spotted wilt virus the second year. In both 2006 and 2007 field trials compost tea was not …

The Molecular Characterization Of The Virus And Virus-Like Agents Present In Ta Tao 5 Germplasm Of Prunus Persica , Diana Marini

All Dissertations

Peach production in the southeastern United States is limited by late spring freezes. Ta Tao 5 germplasm, used either as an interstem or by chip bud inoculation, has been shown to delay bloom and avoid the effects of these late freezes. The growth modification is graft transmissible and the germplasm has been found to be infected with ACLSV, APruV-3, and PLMVd. Using a combination of PCR, cloning, and sequencing techniques, a molecular characterization of the three graft-transmissible agents present in Ta Tao 5 has been completed.

The complete nucleotide sequence of the genome of the isolate of ACLSV (ACLSV-Ta Tao …

Enhancing The Ability Of Panicum Virgatum To Survive Flooding And Its Effects On Soil Activity When Used For Lakeshore Stabilization, Lee Edwards

All Dissertations

Reservoirs in upstate South Carolina are subject to erosion and vegetation has been placed to help stabilize banks, but soils are nutrient-poor and have high bulk densities. Panicum virgatum L. (switchgrass) has been planted in several sites, and it is hypothesized that over time, changes in microbial activity and soil quality will occur in response to the planting. As vegetated sites aged, acid phosphomonoesterase, nitrate reductase, and dehydrogenase activity increased. Low values of nitrogen fixation and substrate-induced respiration were measured at all sites with no statistical differences between sites. Fatty acids indicative of Gram negative bacteria were found in vegetated …

Maestra2: A Model For Simulating Spatially Explicit Carbon Dioxide Exchange Rates Among Species' Water Stress Response, Robert Reynolds

All Theses

MAESTRA2, a species specific mechanistic model, was parameterized to estimate water use, carbon accumulation and organ specific respiration of five deciduous tree species under both irrigated and water stressed conditions. The model was validated using temporally and spatially explicit ecophysiological data to account for seasonal changes in species physiology. The following tree species: Acer rubrum L. 'Summer Red' (A. rubrum), Betula nigra (B. nigra), Paulownia elongata (P. elongata), Quercus nuttallii (Q. nuttallii), and Quercus phellos (Q. phellos) were intensively measured and organ specific destructively harvested samples were compared to modeled estimates of carbon accumulation. Among species, we observed variability in …

Center For Grassland Studies Newsletter, Winter 2007, Volume 13, No. 1

Center for Grassland Studies: Newsletters

Contents

• Restoration of Salt Cedar Infestations

• From the Director

• Patch-burn Grazing: Benefits for Both Wildlife Habitat and Livestock Performance by Chris Helzer

• CGS Associates

• Soil Physical Characteristics of Aging Golf Greens by Roch Gaussoin

• Jim Gerrish to Speak at 2007 Nebraska Grazing Conference

Phylogenetic Relationships In Tribe Cariceae (Cyperaceae) Based On Nested Analyses Of Four Molecular Data Sets, Marcia J. Waterway, Julian R. Starr

Aliso: A Journal of Systematic and Floristic Botany

Phylogenetic reconstruction for Carex and relatives in tribe Cariceae is complicated by species richness and nearly cosmopolitan distribution. In this investigation, our main objective was to estimate evolutionary relationships in tribe Cariceae using DNA sequence data from two spacer regions in nuclear ribosomal genes (ITS and ETS-1f) combined with noncoding chloroplast DNA (trnL intron, trnL–trnF intergenic spacer, and trnE–trnD intergenic spacers). Parsimony analyses of separate and combined data and Bayesian analysis of the combined data matrix revealed strong support for monophyly of tribe Cariceae and for monophyly of two major lineages, one …

An Electronic World Grass Flora, Steve Renvoize, Derek Clayton, Tom Cope, Helen Williamson

Aliso: A Journal of Systematic and Floristic Botany

The development of an electronic world grass flora database is described in which data for 1090 morphological characters gathered for 11,000 species in 700 genera organized according to accepted names. This descriptive information is linked to a synonym database of 60,000 names. Authors, literature references, and the status of each name are also recorded in the database along with geographical distribution and type information. The list of accepted species is linked to a global herbarium of 350,000 specimens at Kew arranged in a phylogenetic sequence at the generic and species levels and according to broad phytogeographic divisions. From the database, …

Classification And Biogeography Of New World Grasses: Anomochlooideae, Pharoideae, Ehrhartoideae, And Bambusoideae, Emmet J. Judziewicz, Lynn G. Clark

Aliso: A Journal of Systematic and Floristic Botany

Molecular data support Anomochlooideae and Pharoideae as the two most basal extant clades within Poaceae. Anomochlooideae are endemic to the New World and have two tribes and two genera including the widespread Streptochaeteae (3–4 spp.) and the critically endangered Anomochloeae (1 sp.) of coastal Bahia, Brazil. Pharoideae are pantropical with one tribe, three genera, and 14 species; all eight species of Pharus occur only in the New World. Bambusoideae and Ehrhartoideae are sister groups and together form a clade sister to Pooideae, although support for this set of relationships is low. Ehrhartoideae are a worldwide subfamily represented in the New …

Phylogenetic Relationships Of The Decumbentes Group Of Paspalum, Thrasya, And Thrasyopsis (Poaceae: Panicoideae: Paniceae), Silvia S. Denham, Fernando O. Zuloaga

Aliso: A Journal of Systematic and Floristic Botany

Paspalum (Poaceae: Panicoideae: Paniceae) includes 330 species distributed mainly in tropical and subtropical regions of America. Due to the large number of species and convergence in many characters, an adequate infrageneric classification is still needed. Studies on Paniceae based on molecular and morphological data have suggested that Paspalum is paraphyletic, including the genus Thrasya, but none of these analyses have included a representative sample of these two genera. In this study, phylogenetic relationships among the informal group Decumbentes of Paspalum, plus subgenera and other informal groups, and the genera Thrasya and Thrasyopsis were estimated. A cladistic analysis under …

The Jeweled Armor Of Tillandsia—Multifaceted Or Elongated Trichomes Provide Photoprotection, Simon Pierce

Aliso: A Journal of Systematic and Floristic Botany

Foliar trichomes of gray-leaved Tillandsioideae (Bromeliaceae) are highly reflective, suggesting a role in protecting the leaf against direct sunlight in exposed niches. The performance of photosystem II, as denoted by the chlorophyll fluorescence characteristic F_v /F_m , was determined for seven Tillandsia species and Vriesea barclayana that were exposed to excessive light, with trichomes either present or removed. Additionally, trichome structure and interaction with light was recorded using extended depth-of-field photomicrography, and reflectance quantified using a novel photographic technique. Trichomes of mesomorphic Type IV life forms (T. cryptantha, T. cyanea) and of the intermediate life …

Chromosome Evolution In Cyperales, Eric H. Roalson, Andrew G. Mccubbin, Richard Whitkus

Aliso: A Journal of Systematic and Floristic Botany

Karyotypic evolution is a prominent feature in the diversification of many plants and animals, yet the role that chromosomal changes play in the process of diversification is still debated. At the diploid level, chromosome fission and/or fusion are necessary components of chromosomal structural change associated with diversification. Yet the genomic features required for these events remain unknown. Here we present an overview of what is known about genomic structure in Cyperales, with particular focus on the current level of understanding of chromosome number and genome size and their impact in a phylogenetic context. We outline ongoing projects exploring genomic structure …

Phylogeny Of Cyperaceae Based On Dna Sequence Data–A New Rbcl Analysis, David A. Simpson, A. Muthama Muasya, Marccus V. Alves, Jeremy J. Bruhl, Sandra Dhooge, Mark W. Chase, Carol A. Furness, Kioumars Ghamkhar, Paul Goetghebeur, Trevor R. Hodkinson, Adam D. Marchant, Anton A. Reznicek, Roland Nieuwborg, Eric H. Roalson, Erik Smets, Julian R. Starr, William W. Thomas, Karen L. Wilson, Xiufu Zhang

Aliso: A Journal of Systematic and Floristic Botany

Since the Monocots II meeting in 1998, significant new data have been published that enhance our systematic knowledge of Cyperaceae. Phylogenetic studies in the family have also progressed steadily. For this study, a parsimony analysis was carried out using all rbcL sequences currently available for Cyperaceae, including data for two new genera. One of the four subfamilies (Caricoideae) and seven of the 14 tribes (Bisboeckelereae, Cariceae, Cryptangieae, Dulichieae, Eleocharideae, Sclerieae, Trilepideae) are monophyletic. Subfamily Mapanioideae and tribe Chrysitricheae are monophyletic if, as the evidence suggests, Hellmuthia is considered a member of Cypereae. Some other features of our analysis include: …

Phylogenetic Implications Of A Unique 5.8s Nrdna Insertion In Cyperaceae, Julian R. Starr, Geneviève Gravel, Anne Bruneau, A. Muthama Muasya

Aliso: A Journal of Systematic and Floristic Botany

The purpose of this study was to assess the phylogenetic utility of a large insertion (3 bp) in the 5.8S gene of nuclear ribosomal DNA (nrDNA) in Cyperaceae and selected Juncaceae. This was done by reconstructing the character evolution of the insertion on a phylogeny derived from rbcL sequences. Results suggest that the insertion was gained once at the base of Cyperaceae followed by multiple losses in its most-derived taxa. Despite several homoplastic losses (CI = 0.20), the pattern of insertion loss (RI = 0.88), and base pair variation within the insertion were useful for defining sedge clades at …

Chromosome Number Changes Associated With Speciation In Sedges: A Phylogenetic Study In Carex Section Ovales (Cyperaceae) Using Aflp Data, Andrew L. Hipp, Paul E. Rothrock, Anton A. Reznicek, Paul E. Berry

Aliso: A Journal of Systematic and Floristic Botany

Phylogenetic analysis of amplified fragment length polymorphisms (AFLP) was used to infer patterns of morphologic and chromosomal evolution in an eastern North American group of sedges (ENA clade I of Carex sect. Ovales). Distance analyses of AFLP data recover a tree that is topologically congruent with previous phylogenetic estimates based on nuclear ribosomal DNA (nrDNA) sequences and provide support for four species groups within ENA clade I. A maximum likelihood method designed for analysis of restriction site data is used to evaluate the strength of support for alternative topologies. While there is little support for the precise placement of …

Plasticity Of Chasmogamous And Cleistogamous Reproductive Allocation In Grasses, Gregory P. Cheplick

Aliso: A Journal of Systematic and Floristic Botany

Cleistogamy is more common in grasses than in any other angiosperm family. Both self-fertilized cleistogamous (CL) spikelets and open-pollinated chasmogamous (CH) spikelets are typically produced. Relative allocation to CL and CH varies among species and populations, and is influenced by ontogeny and environment. The balance between reproductive modes can be expressed as a CH/CL ratio. This ratio is very plastic, and stressful conditions can result in values Amphicarpum purshii, an annual with subterranean CL spikelets, CH/CL declined as density increased because CH decreased more than CL as size was reduced by intraspecific competition. In the shade-tolerant annual Microstegium vimineum, …

Phenotypic Plasticity May Facilitate Invasion By Aegilops Triuncialis, Andrew R. Dyer

Aliso: A Journal of Systematic and Floristic Botany

One great obstacle to understanding the invasion of nonnative species into native ecosystems is the lack of information on the population biology of the invading species. In particular, morphological and physiological adaptations and potential for phenotypic plasticity will strongly influence a species’ ability to persist and spread in newly invaded ecosystems. Phenotypic plasticity can buffer populations from selection thereby allowing them to survive the establishment phase of the invasion. The annual grass Aegilops triuncialis (Poaceae, Triticeae) has become highly invasive in California (USA) and provides an opportunity to investigate the importance of phenotypic plasticity to persistence and spread in new …

A Systematic Approach To Subtribe Loliinae (Poaceae: Pooideae) Based On Phylogenetic Evidence, Pilar Catalán, Pedro Torrecilla, José A. López-Rodríguez, Jochen Müller, Clive A. Stace

Aliso: A Journal of Systematic and Floristic Botany

Loliinae (Poaceae, Pooideae) encompass a large group of genera closely related to Festuca, the largest genus in the subtribe, which as traditionally circumscribed has been shown to be highly paraphyletic. In this investigation we combined molecular and morphological data representing 20 genera of Loliinae and closely related subtribes. Combined analysis of nucleotide sequences from the nuclear ITS and chloroplast trnL–F regions and structural characters recovered a consensus topology that shows Loliinae to be monophyletic and possessing two main clades—the fine-leaved Festuca clade that includes Ctenopsis, Micropyrum, Narduroides, Psilurus, Vulpia, and Wangenheimia, and …

Phylogeny Of Poa (Poaceae) Based On Trnt–Trnf Sequence Data: Major Clades And Basal Relationships, Lynn J. Gillespie, Annie Archambault, Robert J. Soreng

Aliso: A Journal of Systematic and Floristic Botany

Poa, the largest genus of grasses (Poaceae) with over 500 species, occurs throughout temperate and boreal regions in both hemispheres. A phylogenetic study of Poa based on trnT–trnF chloroplast DNA sequence data is presented focusing on basal relationships, major clades, generic boundaries, and placement of putatively closely related genera. Results support the monophyly of the main lineage of Poa if subgen. Andinae is excluded and Anthochloa, Austrofestuca, Dissanthelium (at least in part), and Eremopoa are included. The main Poa clade and subgen. Andinae resolve within a strongly supported Poinae–Alopecurinae–Miliinae clade (PAM). The subdivision of …