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2006

Plant Sciences

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Long-Term Evaluation Of Liquid Vs. Granular Nitrogen Fertilization On Creeping Bentgrass [Agrostis Stoloniferous L. Var. Palustris Huds.] And Hybrid Bermudagrass [Cynodon Dactylon (L.) Pers. X C. Transvaalensis Burtt-Davy] Performance, Frederick Totten Dec 2006

Long-Term Evaluation Of Liquid Vs. Granular Nitrogen Fertilization On Creeping Bentgrass [Agrostis Stoloniferous L. Var. Palustris Huds.] And Hybrid Bermudagrass [Cynodon Dactylon (L.) Pers. X C. Transvaalensis Burtt-Davy] Performance, Frederick Totten

All Dissertations

Limited turfgrass research comparing the efficiency of foliar to granular fertilizers exists. To expand upon previous research and to determine advantages and disadvantages between dry and liquid fertilizers applied to turf, research was conducted at Clemson University to compare the efficiency of three nitrogen (N) carriers (100% granular, 100% liquid, and 50% granular + 50% liquid) using N rates ranging from 98 to 390 kg ha-1 on growth and performance of creeping bentgrass and ultra-dwarf bermudagrass.

Studies were conducted in 2003 and 2004 to evaluate liquid and/or granular N fertilization on turfgrass quality, clipping yield, and root biomass of `L-93 ...


Thatch Control, Winter Painting, And Plant Growth Regulator Management On Golf Course Putting Greens, Steven Long Dec 2006

Thatch Control, Winter Painting, And Plant Growth Regulator Management On Golf Course Putting Greens, Steven Long

All Theses

No abstract provided.


Horizontal Gene Transfer To Bacteria Of An Arabidopsis Thaliana Abc Transporter That Confers Kanamycin Resistance In Transgenic Plants, Kellie Parks Burris Dec 2006

Horizontal Gene Transfer To Bacteria Of An Arabidopsis Thaliana Abc Transporter That Confers Kanamycin Resistance In Transgenic Plants, Kellie Parks Burris

Masters Theses

The use of antibiotic resistance markers is an important tool in the production and selection of transgenic plants. There have been increased concerns about the potential horizontal gene transfer (HGT) from transgenic plants to bacteria of medical and environmental importance. Until recently all antibiotic resistance genes used in transgenic studies have been bacterial in origin. An Arabidopsis thaliana ABC transporter, Atwbc19, was the first plant gene shown to confer kanamycin resistance when overexpressed in transgenic plants. The Atwbc19 gene was evaluated for its ability to transfer antibiotic resistance to Escherichia coli, which are found in the human gut and environment ...


Established Predators Of Fiorinia Externa Ferris (Hemiptera: Diaspididae) On Eastern Hemlock (Tsuga Canadensis (L.) Carriere) In Urban And Forest Sites, Christine Ann Lynch Dec 2006

Established Predators Of Fiorinia Externa Ferris (Hemiptera: Diaspididae) On Eastern Hemlock (Tsuga Canadensis (L.) Carriere) In Urban And Forest Sites, Christine Ann Lynch

Masters Theses

A project was initiated in September 2004 to determine the indigenous predators of Fiorinia externa Ferris, the elongate hemlock scale (EHS), on eastern hemlock and their impact on the pest populations. Branch samples were taken monthly from four sites (two forest and two urban) in eastern Tennessee and western North Carolina to assess predator damage from October 2004 to April 2006. Predators of this exotic pest were collected from beat sheet samples from September 2004 to May 2006. Laboratory tests were conducted from field-collected predators to assess food consumption, feeding behavior, and intraguild competition among predators of EHS. From field ...


Probing Precursor Interactions With The Chloroplast Import Apparatus, Sarah Jean Wright Dec 2006

Probing Precursor Interactions With The Chloroplast Import Apparatus, Sarah Jean Wright

Masters Theses

The majority of plastid proteins are nuclear-encoded and imported post-translationally. A cleavable N-terminal extension, the transit peptide, targets these preproteins to the plastid. Transit peptides show very little primary sequence homology, yet are able to direct the precursor protein to interact with the protein components of the translocation complexes located within the inner and outer membranes of the chloroplast. In this study, a semi-conserved motif of the transit peptide, (F/W)(P/G)h(R/K) has been targeted for deletion in order to probe its importance. Two corresponding regions were deleted in the transit peptide of the precursor to ...


Latex Of Sciadopitys Verticillata (Thunb.) Siebold And Zuccarini: Antibiotic Properties, Phytochemistry, And Inhibition Of Adventitious Rooting Of Stem Cuttings., David Ira Yates Aug 2006

Latex Of Sciadopitys Verticillata (Thunb.) Siebold And Zuccarini: Antibiotic Properties, Phytochemistry, And Inhibition Of Adventitious Rooting Of Stem Cuttings., David Ira Yates

Electronic Theses and Dissertations

Sciadopitys verticillata was subjected to three propagation treatments designed to inhibit coagulation of its latex-like sap at the cut ends of the stem cuttings. Twenty-four hour soaking in water prior to rooting hormone application significantly enhanced production of adventitious roots. Old wood stem cuttings from shade-grown trees rooted at higher proportions than stem cuttings collected from sun-grown trees. Height, age, and place of origin of the source trees were not important factors in successful rooting. Antibacterial activity against some human pathogens and soil bacterial species was detected in latex application trials but the antibiotic activity was not related to the ...


Determining Wear Tolerance Of Turfgrass Species For Athletic Fields In The Transition Zone, Jordan Rhea Goddard Aug 2006

Determining Wear Tolerance Of Turfgrass Species For Athletic Fields In The Transition Zone, Jordan Rhea Goddard

Masters Theses

A study to evaluate the performance of four different turfgrass varieties under simulated athletic field traffic in the transition zone was conducted in Tennesseeand Arkansas. ‘Thermal Blue’ hybrid bluegrass (Poa arachnifera Torr. x P. pratensis L.) has been introduced as a bluegrass variety bred for increased heat and drought tolerance. This variety provides a possible alternative to bermudagrass varieties in transition zone athletic fields. ‘Thermal Blue’ was compared to common bermudagrass (Cynodon dactylon L. Pers.) varieties ‘Riviera’ and ‘Quickstand’ and the hybrid bermudagrass (C. dactylon L. Pers. x C. transvaalensis Burt-Davy) variety ‘Tifway’. Each turfgrass species was tested with and ...


Expression Analysis Of Auxin Regulated Genes In Populus, Sara S. Jawdy Aug 2006

Expression Analysis Of Auxin Regulated Genes In Populus, Sara S. Jawdy

Masters Theses

Due to its many advantageous characteristics, such as a small sequenced genome, ease of vegetative propagation and availability of genomic tools and databases, Populus is widely becoming accepted as the model species among trees. In addition, DOE has chosen hybrid poplar as the model bioenergy feedstock tree. Due to the growing importance of the Populus species, genetic and genomic resources (EST and BLAST databases, genetic maps, etc.) are becoming increasingly available and are leading to a greater understanding of the functionality of the Populus genome. The goal of this study was to use these resources to further characterize the genetic ...


Oxalate Production And Cation Translocation During Wood Biodegredation By Fungi, Jonathan S. Schilling Aug 2006

Oxalate Production And Cation Translocation During Wood Biodegredation By Fungi, Jonathan S. Schilling

Electronic Theses and Dissertations

Wood biodegradation is primarily caused by Basidiomycetous white or brown rot fungi. White rot fungi are unique in degrading lignin, while brown rot fungi circumvent lignin to degrade holocellulose via iron-dependent oxidative chemistry. Both groups of fungi produce oxalate during wood metabolism, and oxalic acid secretion may promote wood decay by reducing pH, mobilizing iron, detoxifying copper, and immobilizing calcium. The function of oxalate during wood decay remains unclear, however, primarily due to difficulties in extracting bound oxalate and to inconsistencies among analytical techniques. This work aims to improve oxalate quantification during wood biodegradation and to better characterize fungal oxalate ...


The Fate And Transport Of Nitrogen (N) And The Effect Of Emergent Plants On Natural Treatment Of N-Species At Las Vegas Wash, Nevada, Tanju Kiriscioglu May 2006

The Fate And Transport Of Nitrogen (N) And The Effect Of Emergent Plants On Natural Treatment Of N-Species At Las Vegas Wash, Nevada, Tanju Kiriscioglu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study is to analyze the effect of emergent plant communities at Las Vegas Wash (the System) using a system dynamics modeling approach. Understanding the dynamics of nitrogen (N —major polluting nutrient in the Wash) that enters the System is important because it occasionally causes algal blooms, choking Lake Mead through excessive eutrophication. Emergent plant communities are an integral part of wetland ecosystems and they play a crucial role in natural treatment of nutrients. This study is intended to test this hypothesis.

The study makes use of Wash data from reliable sources (Las Vegas Valley Water District ...


Management Of Hybrid Bluegrass (Poa Arachnifera Torr. X Poa Pratensis L.) In The Transition Zone, Travis Charles Teuton May 2006

Management Of Hybrid Bluegrass (Poa Arachnifera Torr. X Poa Pratensis L.) In The Transition Zone, Travis Charles Teuton

Doctoral Dissertations

Dura Blue™ and Thermal Blue™ hybrid bluegrass (Poa arachnifera Torr. x Poa pratensis L.) have been selected for increased heat and drought tolerance and offer an alternative to traditional Kentucky bluegrass and tall fescue in the transition zone. Dura Blue and Thermal Blue were compared to Apollo™ Kentucky bluegrass, Dynasty™ tall fescue, and Kentucky 31 tall fescue. All turfgrass species tested were acceptable for use in the transition zone. Thermal Blue should be seeded from 50 to 150 kg seed/ha. Thermal Blue should be seeded in September for highest quality and most rapid turf cover. However, January and April ...


Potassium And Cultivar Effects On Carbohydrate Partitioning In Upland Cotton, Jenny Dale Clement May 2006

Potassium And Cultivar Effects On Carbohydrate Partitioning In Upland Cotton, Jenny Dale Clement

Masters Theses

The indeterminate growth habit of upland cotton (Gossypium hirsutum L.) reduces the efficiency of yield formation when grown as an annual for its lint. Altering the determinacy may provide greater carbohydrate partitioning to reproductive structures, allowing higher yields. Another factor that may influence partitioning is potassium (K) nutrition. Potassium is essential for physiological and biochemical processes including translocation. It is necessary for ATP production, which is crucial for phloem loading and unloading. A three-year experiment was conducted at the West Tennessee Research and Education Center to evaluate carbohydrate partitioning in Paymaster 1218BG/RR (PM1218), a relatively determinate cultivar, and Deltapine ...


Risk Assessment Of Genetically Modified Crops By Direct Tracking Pollen Movement And Testing Crop Genetic Load Using Directly Transformed Brassica Rapa With Bt Cry1ac And Gfp Genes, Hong Seok Moon May 2006

Risk Assessment Of Genetically Modified Crops By Direct Tracking Pollen Movement And Testing Crop Genetic Load Using Directly Transformed Brassica Rapa With Bt Cry1ac And Gfp Genes, Hong Seok Moon

Masters Theses

One concern with crop biotechnology is that there might be crop to weed transgene flow, which could result in more invasive and competitive weed populations. Transgene expression, introgression of crop genes, and other ecological factors may alter the fitness or productivity of weed populations. The Brassica napus (crop) to Brassica rapa (weed) model to assess transgene flow and consequences has been widely used. In this study, weedy accessions of Brassica rapa were transformed with Bacillus thuringiensis (Bt) cry1Ac- and green fluorescence protein (GFP)- coding transgenes using Agrobacterium to develop plants to be subsequently used in risk assessment research. Regenerated transgenic ...


Mowing And Light-Weight Rolling Of Creeping Bentgrass (Agrostis Stolonifera L.) Putting Greens During Summer Heat Stress Periods In The Transition Zone, William Daniel Strunk May 2006

Mowing And Light-Weight Rolling Of Creeping Bentgrass (Agrostis Stolonifera L.) Putting Greens During Summer Heat Stress Periods In The Transition Zone, William Daniel Strunk

Masters Theses

A major challenge for golf course superintendents in the transition zone is to manage Agrostis stolonifera L. (creeping bentgrass) putting greens during heat stress periods of June, July, and August. In 2004 and 2005, a study was conducted to compare the effects of alternating rolling and mowing with traditional methods of everyday mowing on the green speed, turf quality, and disease occurrence creeping bentgrass putting greens in the transition zone. Treatments consisted of mowing six days week-1 without rolling, mowing six days week-1 with rolling three days week-1, and mowing three days week-1 alternating with rolling ...


Biogeographical Origins And Phytogeny Of The Endemic Hawaiian Species Ofcibotium (Dicksoniaceae): A Molecular Perspective Based On Atpb Sequences, Christine Nelson Apr 2006

Biogeographical Origins And Phytogeny Of The Endemic Hawaiian Species Ofcibotium (Dicksoniaceae): A Molecular Perspective Based On Atpb Sequences, Christine Nelson

Life and Environmental Sciences Undergraduate Theses

A great deal of speculation exists as to the biogeographical origins and phylogeny of endemic Hawaiian ferns; yet only a handful of studies has actually examined the evolution of these endemics and their relationships to continental species. The fern genus Cibotium (Dicksoniaceae), consisting of four Hawaiian endemics and five non-Hawaiian species, is the focus of this study. The goals of my research were to resolve whether Hawaiian Cibotium is monophyletic and to test the hypothesis that the common ancestor of Hawaiian Cibotium originated from the IndoPacific region. Although the long-distance dispersal mechanism of fern spores to Hawaii was not directly ...


Molecular Phylogenetics And Biogeography Of Hawaiian Members Of The Pteridophyte Genus Cibotium (Dicksoniaceae), Annabelle Kleist Apr 2006

Molecular Phylogenetics And Biogeography Of Hawaiian Members Of The Pteridophyte Genus Cibotium (Dicksoniaceae), Annabelle Kleist

Life and Environmental Sciences Undergraduate Theses

Although ferns comprise a significant proportion of Hawaii’s native vascular-plant flora, few phylogenetic studies have been performed to infer relationships among taxa and to deduce their biogeographical origins. Species from the pteridophyte genus Cibotium can be found among the canopy in the Island’s montane regions and were the focus of this study. Four species of Cibotium are endemic to the Hawaiian Archipelago and ten species exist worldwide. The goal of this study was to determine whether Hawaiian Cibotium is monophyletic and to discover the biogeographical origins ofthe species. Two chloroplast DNA fragments, trnL-F IGS and rbcL, were sequenced ...


Biogeographical Origins Of Hawaiian Diplopterygium Pinnatum By Long Distance Wind Dispersal, Kris Christensen Apr 2006

Biogeographical Origins Of Hawaiian Diplopterygium Pinnatum By Long Distance Wind Dispersal, Kris Christensen

Life and Environmental Sciences Undergraduate Theses

This study was designed to investigate a possible biogeographical origin and mechanism of dispersal ofthe Hawaiian fern Diplopterygium pinnatum. Molecular phylogenetic analyses were conducted on trnL-F and rbcL, cpDNA regions, for seven species of the genus Diplopterygium and three outgroups. Maximum parsimony and maximum likelihood analyses were used for phylogenetic reconstruction. Three hypotheses were tested: that the ancestor ofD. pinnatum originated from 1) an IndoPacific source and traveled to Hawaii via the jet stream, 2) an American source and traveled to Hawaii via the trade winds, or 3) an Austral source and traveled to Hawaii by a combination of an ...


The Effects Of Light Reduction Treatments On Mobile Epifaunain An Amphibolis Griffithii (Black) Den Hartog Seagrass Ecosystem, Helen Barwick Jan 2006

The Effects Of Light Reduction Treatments On Mobile Epifaunain An Amphibolis Griffithii (Black) Den Hartog Seagrass Ecosystem, Helen Barwick

Theses : Honours

One of the main anthropogenic disturbances to seagrass meadows in Australia is reduction in light availability, through nutrient enrichment or suspended sediments. Dredging can create suspended sediment plumes from the expulsion of particulates into the water column and in tum reduces light penetration to seagrass ecosystems. Preliminary investigations have demonstrated that light reduction for different intensities and durations results in reduced seagrass and epiphytic algae biomass. The main aim of this study was to determine the effects of different intensities and durations of light reduction on epifaunal assemblages in Amphibolis griffithii seagrass meadows in Jurien Bay, Western Australia. This was ...


Water Stress Vulnerability Of Four Banksia Species In Contrasting Ecohydrological Habitats On The Gnangara Mound, Western Australia., Caroline Canham Jan 2006

Water Stress Vulnerability Of Four Banksia Species In Contrasting Ecohydrological Habitats On The Gnangara Mound, Western Australia., Caroline Canham

Theses : Honours

The distribution of obligate and facultative phreatophytic vegetation reflects the gradient of ecohydrological habitats in a landscape. Preliminary investigations of Banksia vulnerability to xylem embolism have reported that obligate phreatophytes are more susceptible to water stress than facultative phreatophytes (Froend & Drake 2006). A quantitative measure of plant susceptibility to water stress is vital when establishing environmental water requirements. This study investigated interspecific differences in vulnerability to water stress for two facultative phreatophytes (B. attenuata and B. menziesii) and two obligate pln·eatophytes (B. ilicifolia and B. littoralis) at the same position along an ecohydrological gradient on the Gnangara Groundwater Mound ...


Pollen Characteristics Of Grevillea Species Determined By In Vitro Germination, Rebecca Parsons Jan 2006

Pollen Characteristics Of Grevillea Species Determined By In Vitro Germination, Rebecca Parsons

Theses : Honours

Germination of pollen in vitro is a common technique used to assess the ability of pollen to germinate under a variety of conditions. The ability to determine the viability of a pollen grain, and optimal conditions for maximum germination and storage are important for hybridisation. A means of storing pollen, while maintaining viability, enables inter-species hybridisation between species that are spatially and temporally (flowering time) separated. The ultimate aim of hybridisation is seed set and in order to increase this in a genus renowned for a very low fruit to flower ratio, maximum pollen germination must be obtained. Therefore, by ...


Genetic Diversity And Gene Flow In Fragmented Populations Of The Rare Shrub, Calothamnus Sp. Whicher, Sean Stankowski Jan 2006

Genetic Diversity And Gene Flow In Fragmented Populations Of The Rare Shrub, Calothamnus Sp. Whicher, Sean Stankowski

Theses : Honours

Ca/othamnus sp. Whicher (Myrtaceae) is a narrow range endemic shrub restricted to ironstone soils near the town of Busselton in south-western Australia. Due to extensive land clearing for agriculture and mineral exploration, the species is fragmented over the majority of its range. In the present study, microsatellite markers were used to characterise levels of genetic diversity and describe levels of differentiation and gene flow among seven small, isolated road verge populations. Allelic diversity within the taxon over the six microsatellites was high (A = 17.6 ± 1.6). Diversity within populations was considerably lower (A = 5.19 ± 1.27), and ...


Localization Of Diplodia Pinea In Diseased And Latently-Infected Pinus Nigra, Jennifer Lee Flowers Jan 2006

Localization Of Diplodia Pinea In Diseased And Latently-Infected Pinus Nigra, Jennifer Lee Flowers

University of Kentucky Doctoral Dissertations

Diplodia pinea causes Diplodia tip blight on more than 30 different pine species. During the past 10 years, Diplodia tip blight has emerged as a serious problem in landscape and Christmas tree farms in this region. Surveys of diseased and symptomless Austrian pines revealed that latent infections of symptomless shoots by D. pinea were common. Latent infections may account for the recently observed rapid decline of mildly diseased pines in our region. To investigate the colonization habits of D. pinea within its host, molecular cytology was attempted and traditional histology was performed on naturally infected, diseased and asymptomatic Austrian pine ...


Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska Jan 2006

Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska

Retrospective Theses and Dissertations

Iron deficiency chlorosis (IDC) and soybean cyst nematode (SCN; Heterodera glycines) infestation are major factors that contribute to soybean (Glycine max Merr.) yield reduction in the Midwest. The IDC is often associated with soybean grown on high pH, calcareous soils. In addition, it was documented that SCN population density is higher in high pH soils. The objectives of this paper were to assess the proportion of within-field soybean yield and SCN variability that could be explained by soil pH, calcium carbonate equivalent (CCE), and a previously defined alkalinity stress index (ASI). Aerial images from 21 fields planted to SCN-resistant or ...


Management Strategies To Improve Soybean Yield In High Ph Soybean Cyst Nematode Infested Fields , Vladimir Azevedo Da Costa Jan 2006

Management Strategies To Improve Soybean Yield In High Ph Soybean Cyst Nematode Infested Fields , Vladimir Azevedo Da Costa

Retrospective Theses and Dissertations

Soybean cyst nematode (Heterodera glycines; SCN) causes the greatest yield losses of all diseases on soybean [Glycine max (L.) Merr.] in Iowa. Growing SCN-resistant varieties in rotation with non-host crops and SCN-susceptible varieties is the current management recommendation for SCN in Iowa. Previous research has shown that SCN population densities are positively correlated with soil pH. The correlation may reduce the efficacy of the current SCN management recommendation in northern and central Iowa, which is located in the Des Moines lobe area, a calcareous soil area with high pH soil. The hypothesis for this research is that additional management strategies ...


Enhancement Of Plant Performance And Biochemical Constituents In Field And Hairy Root Production Of Echinacea , Fredy Rolando Romero Orellana Jan 2006

Enhancement Of Plant Performance And Biochemical Constituents In Field And Hairy Root Production Of Echinacea , Fredy Rolando Romero Orellana

Retrospective Theses and Dissertations

Echinacea is a commercially important source of natural products and phytopharmaceuticals. Echinacea products currently constitute a significant portion of the rapidly growing, multi-billion dollar natural products market. This popularity has led to the expansion of commercial cultivation of Echinacea and the need to find alternative methods to meet the increasing demands of the phytopharmaceutical market. Two methods of producing biochemical constituents in commercial use include extraction from field-grown plants and in vitro hairy root production;Echinacea seeds in the wild typically show a high degree of dormancy. In order to enhance Echinacea seed germination for field production, alternative methods to ...


A Quantitative Trait Response Evaluation To Selection In The Bs13(S) Maize (Zea Mays L.) Population , Clinton J. Turnbull Jan 2006

A Quantitative Trait Response Evaluation To Selection In The Bs13(S) Maize (Zea Mays L.) Population , Clinton J. Turnbull

Retrospective Theses and Dissertations

Seven cycles of half-sib recurrent selection were conducted in the BSSS maize population followed by ten cycles of S2 progeny recurrent selection. The population under S2 progeny recurrent selection is formally known as BS 13(S). The selection criteria have always placed importance on high grain yield, low grain moisture, and reduced plant lodging. Two evaluations estimating the response of multiple agronomic traits in multiple response units including the population sampled at F IS = 0, FIS = 0.5, and FIS = 0.75 levels of inbreeding, and multiple testcrosses of the population were conducted. The average response of grain yield in ...


Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong Jan 2006

Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong

Retrospective Theses and Dissertations

Autophagy is a process in which cytoplasmic components are degraded in the vacuole. It occurs when organisms are subjected to environmental stress conditions or during certain stages of development. Upon induction of autophagy, a portion of cytoplasm is surrounded by a double membrane structure to form an autophagosome. The outer membrane of the autophagosome then fuses with the vacuole and the inner membrane and its contents are degraded by vacuolar hydrolases. The morphological characteristics of autophagy have been observed in plants for decades and several autophagy defective mutants have been isolated recently; however, little is known about the molecular mechanism ...


Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez Jan 2006

Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez

Retrospective Theses and Dissertations

Soybean grain contains isoflavones that may prevent various human diseases. Previous studies in Canada found that K fertilization and high grain K concentration can result in increased isoflavones concentration in grain, but effects were inconsistent across sites and soil-test K (STK) levels. The objective of this study was to assess (1) effects of K fertilization on the concentration of isoflavones and K in soybean grain and (2) relationships between soybean grains K concentration, isoflavone concentration, and yield. The study was based on analyses of grain collected from selected treatments and years of six Iowa long-term experiments that investigated effects of ...


The Mechanism Of Arabidopsis Immutans Variegation , Aigen Fu Jan 2006

The Mechanism Of Arabidopsis Immutans Variegation , Aigen Fu

Retrospective Theses and Dissertations

The Arabidopsis immutans (im) is variegated with green sectors and white sectors containing defective plastids due to a nuclear gene mutation. IM is a plastid terminal oxidase (PTOX) sharing similarity with mitochondrial alternative oxidase (AOX). In order to better understand IM's biological roles and variegation mechanism of im, I characterized im plants at different levels;A structural model of IM, in which the diiron reaction center is composed of two conserved histidine and four glutamate residues, was tested by mutagenesis in vitro and in planta. It that these six conserved residues were found essential for IM activity and do ...


Effects Of Crop Rotation And Nitrogen Fertilization On Soil Nitrate Concentration And Corn Yield , Enrique Ortiz-Torres Jan 2006

Effects Of Crop Rotation And Nitrogen Fertilization On Soil Nitrate Concentration And Corn Yield , Enrique Ortiz-Torres

Retrospective Theses and Dissertations

Increasing concerns about production cost and environmental impacts of N fertilization require improving N management. The objectives of this study were to evaluate effects of cropping sequences and N fertilization on (1) corn yield and yield stability and (2) soil nitrate concentration in two Iowa long-term rotation experiments and (3) to assess the performance of the late spring nitrate test (LSNT) to assess N availability for corn in several cropping sequences. The experiments were near Kanawha (20 yrs) and Nashua (26 yrs) and N fertilization rates for corn were 0, 90, 180, 270 kg N ha -1. Rotations in Kanawha ...