Digital Commons Network^™

The Effect Of Nitrogen Soil Concentration On Leaf Fluorescence In Zea Mays, Ashton Garbutt, Daniel Rossie, Anup Solsi

Featured Research

Macronutrients in the soil are essential to the growth and development of a plant. One of the most important nutrients to a plants growth is nitrogen. Nitrogen has been directly correlated to photosynthetic output in various studies and this relationship is the subject of this experiment. Since nitrogen has an effect on photosynthetic rate, there should be a correlation between nitrogen and fluorescence – a form of energy dissipation. This study attempted to show that nitrogen concentration in the soil is inversely proportional to fluorescence of the plant because the more nitrogen in the soil, the more energy should be …

The Effect Of Proximity To A Highway On The Health Of Malosma Laurina Leaves, Jessica Bermea, Haley Clayton, Jack Klobas

Featured Research

Due to an increase in air pollutants, heavy metal contaminates, and other adverse ecological conditions that plants near a road endure, it was hypothesized that plant species situated near a road would have a detectable decrease in photosynthetic performance when compared to plants away from the road. This investigation evaluated the in vivo photosynthetic status of two Malasma Laurina pairs with differing microhabitats, adjacent to the Pacific Coast Highway and 100 meters away from a Pacific Coast Highway. Maximum quantum yield and stomatal conductance measurements were recorded for each group. On average, the maximum quantum yield was greater on plants …

The Effect Of Hydration Status On Tensile Strength Of The Leaves Of Elymus Glaucus, Chelsie Corbett, Uri Hong, Scott Davis

Featured Research

Tensile strength and water potential are both factors that are essential to the life and survival of a plant. Tensile strength is a measure of the amount of force that a plant can undergo before tissue damage and breakage occur. The primary objective of this study was to examine the correlation between tensile strength and leaf hydration status, or water potential. The water potential of leaves of a monocot grass native to North America, Elymus Glaucus, commonly known as blue wildrye, was measured using the Scholander-Hammel Pressure Chamber. The tensile strength of hydrated and of dehydrated leaves was measured …

The Effects Of Agitation Upon Plant Anatomy In Phaseolus Vulgaris, Craig Sutter, Nicholas Huron

Featured Research

The earthquake that struck Japan’s coast a month ago gained national attention for the damage caused by the tsunami that was caused by the earthquake. Japan’s coast is subject to multiple earthquakes each year with tremors and aftershocks following. The quakes are bound to have an effect on the growth and development of Camellia sinensis, the tea plant, which is one of the most important exports of Japan. Due to the time restraints of this project, C. sinensis were not tested, instead two week old Phaseolus vulgaris were used to show the effects of constant agitation which might mimic …

Effects Of Dehydration Stress On The Dark Adapted Fluorescence (Fv/Fm) Of Giant Bladder Kelp (Macrocystis Pyrifera), J. Avery Powell, Leah Smith

Featured Research

The unique semi-diurnal tide system of Southern California suspends beach wrack along the beaches for approximately six hour periods before being washed back into the ocean. It has been noted in prior research that beach wrack is an essential part of Southern California's costal ecology but not much research has been done to learn about the viability of beach wrack as it dehydrates on the beach. To better understand the viability of wrack as it travels through these hydration changes, this study tested the effect of dehydration and rehydration on the fronds of Macrocystis pyrifera as they have been partially …

Exploring The Open-Close Mechanism Of Dimorphotheca Aurantiaca: Day Versus Night And Cold Versus Hot Temperatures, Tommy Chung, Kathleen Aguilar, Sunny Kim

Featured Research

In the spring of every year on Pepperdine University’s campus, patches of hills are covered with the South African native flower Dimorphotheca aurantiaca or more commonly known as the African Daisy. An observation of the opening and closing mechanism of the flower triggered an important question: does the flower change its shape based on temperature or the presence of light? At night, the African Daisy closes and then opens up again in the daytime. Because temperature has such strong effects on different species of ectodermic animals and temperature-sensitive plants, we hypothesized that the change in temperature initiates the flower’s morphological …

Extreme Environments Select For Reproductive Assurance: Evidence From Evening Primroses (Oenothera), Margaret E.K. Evans, David J. Hearn, Kathryn E. Theiss, Karen Cranston, Kent E. Holsinger, Michael J. Donoghue

EEB Articles

• Competing evolutionary forces shape plant breeding systems (e.g. inbreeding depression, reproductive assurance). Which of these forces prevails in a given population or species is predicted to depend upon such factors as life history, eco- logical conditions, and geographical context. Here, we examined two such predictions: that self-compatibility should be associated with the annual life history or extreme climatic conditions.

• We analyzed data from a clade of plants remarkable for variation in breeding system, life history and climatic conditions (Oenothera, sections Anogra and Kleinia, Onagraceae). We used a phylogenetic comparative approach and Bayesian or hybrid Bayesian tests to account …

Mojave Applied Ecology Notes Winter 2011, Scott R. Abella, Alice C. Newton, Kenneth Chittick, Pam Sinanian

Mojave Applied Ecology Notes

Lake Mead’s collaborative applied science research program; “annoying the elephant” - ruminations on active management by Alice Newton, Lake Mead NRA vegetation manager; 2012 NWRA Lake Mead symposium sneak peak; assessing forest change using dendrochronology in the Spring Mountains.

Discriminating Microsatellites From Macrophomina Phaseolina And Their Potential Association To Biological Functions, R. S. Arias, J. D. Ray, A. Mengistu, B. E. Scheffler

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

One hundred and eighty-two microsatellites or simple-sequence-repeat (SSR) markers for Macrophomina phaseolina were developed. These were tested on 24 isolates of M. phaseolina obtained from seven plant species, and the genetic variation of isolates was studied in relation to potential biological processes that could be affected in this fungus. A total of 120 SSR markers were polymorphic, amplifying >90% of the 24 isolates tested. Thirty percent of the markers showed multiple alleles on individual samples. A large number of markers showed unique alleles in isolates collected from pumpkin and snap bean. DNA sequences corresponding to 43 markers had significant hits …

Field-Scale Soil Property Changes Under Switchgrass Managed For Bioenergy, Marty R. Schmer, M. A. Liebig, K. P. Vogel, Robert B. Mitchell

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The capacity of perennial grasses to affect change in soil properties is well documented but information on switchgrass (Panicum virgatum L.) managed for bioenergy is limited. An on-farm study (10 fields) in North Dakota, South Dakota, and Nebraska was sampled before switchgrass establishment and after 5 years to determine changes in soil bulk density (SBD), pH, soil phosphorus (P), and equivalent mass soil organic carbon (SOC). Changes in SBD were largely constrained to near-surface depths (0–0.05 m). SBD increased (0–0.05 m) at the Nebraska locations (mean=0.16 Mgm^-3), while most South Dakota and North Dakota locations showed declines …

Community Structures Of Fecal Bacteria In Cattle From Different Animal Feeding Operations, Orin C. Shanks, Catherine A. Kelty, Shawn Archibeque, Michael Jenkins, Ryan Newton, Sandra L. Mclellan, Susan M. Huse, Mitchell L. Sogin

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The fecal microbiome of cattle plays a critical role not only in animal health and productivity but also in food safety, pathogen shedding, and the performance of fecal pollution detection methods. Unfortunately, most published molecular surveys fail to provide adequate detail about variability in the community structures of fecal bacteria within and across cattle populations. Using massively parallel pyrosequencing of a hypervariable region of the rRNA coding region, we profiled the fecal microbial communities of cattle from six different feeding operations where cattle were subjected to consistent management practices for a minimum of 90 days. We obtained a total of …

Use Of Gis-Based Site-Specific Nitrogen Management For Improving Energy Efficiency, Kevin F. Bronson, Peter C. Scharf, Newell R. Kitchen

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

To our knowledge, geographical information system (GIS)-based site-specific nitrogen management (SSNM) techniques have not been used to assess agricultural energy costs and efficiency. This chapter uses SSNM case studies for corn (Zea mays L.) grown in Missouri and cotton (Gossypium hirsutum L.) grown in Texas. In five case studies, the impact of SSNM will be compared with blanket N fertilizer recommendations. The five case studies are investigating (I) the impact N on energy produced in cotton production, (2) the impact of variable-rate N for cotton production based on soil nitrate and crop reflectance, (3) the feasibility of variable-rate …

New Records And Ecological Remarks Regarding The Tribe Stomoxyini (Diptera: Muscidae) From Israel, Günter Müller, Jerome Hogsette, Vasiliy Kravchenko, Edita Revay, Yosef Schlein

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The Stomoxyini is a small tribe with only ten genera and 49 known species worldwide (Zumpt 1973) belonging to the Muscidae, one of the largest dipteran. Apart from feeding occasionally on nectar (Müller et al. 2011a), the adult flies of this tribe are obligate blood feeders and can easily be recognized by their conspicuous proboscis adapted for biting and sucking blood (Zumpt 1973). Several members of the tribe, especially Stomoxys and Haematobia species, are major pests of domestic livestock. Two species, Stomoxys calcitrans (Linnaeus 1758) and Haematobia irritans (Linnaeus 1758), cause billions of USD in damages annually in the cattle …

Evapotranspiration Information Reporting: I. Factors Governing Measurement Accuracy, Richard G. Allen, Luis S. Pereira, Terry A. Howell, Marvin E. Jensen

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

More and more evapotranspiration models, evapotranspiration crop coefficients and associated measurements of evapotranspiration (ET) are being reported in the literature and used to develop, calibrate and test important ET process models. ET data are derived from a range of measurement systems including lysimeters, eddy covariance, Bowen ratio, water balance (gravimetric, neutron meter, other soil water sensing), sap flow, scintillometry and even satellite-based remote sensing and direct modeling. All of these measurement techniques require substantial experimental care and are prone to substantial biases in reported results. Reporting of data containing measurement biases causes substantial confusion and impedance to the advancement of …

Beneath The Surface Of Global Change: Impacts Of Climate Change On Groundwater, Timothy R. Green, Makoto Taniguchi, Henk Kooi, Jason J. Gurdak, Diana M. Allen, Kevin M. Hiscock, Holger Treidel, Alice Aureli

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Global change encompasses changes in the characteristics of inter-related climate variables in space and time, and derived changes in terrestrial processes, including human activities that affect the environment. As such, projected global change includes groundwater systems. Here, groundwater is defined as all subsurface water including soil water, deeper vadose zone water, and unconfined and confined aquifer waters. Potential effects of climate change combined with land and water management on surface waters have been studied in some detail. Equivalent studies of groundwater systems have lagged behind these advances, but research and broader interest in projected climate effects on groundwater have been …

Landform, Soil, And Plant Relationships To Nitrate Accumulation, Central Nevada, W.D. Nettleton, F.F. Peterson

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Nitrate (NO₃ ⁻¹) accumulates in Haplocambids and Torrifluvents in inset fan and fan skirt positions in central Nevada. The soils store as much as 17,600 kg of NO3 −1 N ha−1 within the upper 208 cm. This paper provides an explanation. These Holocene soils receive NO₃ ⁻¹ N from mineralization of organic matter and other NO₃ ⁻¹ N sources including snowmelt. The NO₃ ⁻¹ is delivered to soils in the first part of snowmelt in run-off from the higher surfaces. The last part of the melt and the run-off, when sufficient, serve to move the …

A Survey Of The Chemical Content And Medicinal Activity Of Shrub-Steppe Plants Of The Pacific Northwest, Aaron M. John

Undergraduate Honors Theses

A need for new modes of antibiotic therapy has resulted from the increasing incidence of bacterial resistance to drugs. One approach to this problem involves the search for plant compounds that may help to overcome multi-drug resistance. Many plant genera have been utilized in Native American traditional medicine for their beneficial properties. Such plants include the shrub-steppe genera, Eriogonun and Collomia, which have been used as cold remedies, pain relievers, and for antibiotic-related uses. Limited chemical studies of these genera have revealed medicinally useful compounds such as flavonoids and terpenoids, and further research may result in the identification of …

Characterization Of Viral And Host Proteins And Rna Elements In Tombusvirus Replication, Kunj Bihari Pathak

Theses and Dissertations--Plant Pathology

Two thirds of plant viruses are positive-strand RNA viruses including the family Tombusviridae. One of the best-studied members of this family is Tomato bushy stunt virus (TBSV). Like many other viruses, TBSV has much fewer genes when compared to its hosts’ genome. Nevertheless, TBSV utilizes its genome very judiciously. To compensate for a lack of many proteins of its own, it codes for multi-functional replication protein p33 and also co-opts host factors to facilitate its replication.

By using recombinant replication proteins p33 and p92 containing single amino acid changes in protein-protein interaction domains (S1 and S2), I demonstrated that the …

Effects Of Nitrogen On Temporal And Spatial Patterns Of Nitrate In Streams And Soil Solution Of A Central Hardwood Forest, Frank S. Gilliam, Mary Beth Adams

Biological Sciences Faculty Research

This study examined changes in stream and soil water NO3−and their relationship to temporal and spatial patterns of NO3−in soil solution of watersheds at the Fernow Experimental Forest, West Virginia. Following tenfold increases in stream NO3−concentrations over a 13-year period (1969–1981) on untreated WS4, concentrations have declined through 2006. Followingfourfold increases in stream NO3−on treatment WS3 from pretreatment levels to a 1998 maximum, concentrations have declinedthrough 2006, despite additions of N. Concentrations of soil water NO3−were consistently lower for WS4 compared to WS3.Data for soil water NO3−on WS3 versus WS4 followed patterns of net mineralization and nitrification for these watersheds.Nitrogen …

Switchgrass, Kenneth P. Vogel, Gautam Sarath, Aaron J. Saathoff, Robert B. Mitchell

Department of Agronomy and Horticulture: Faculty Publications

17.1 Introduction

Switchgrass (Panicum virgatum L.) is a warm-season perennial grass that is native to North America that is being developed into a biomass energy crop. It has been used in pastures and for conservation purposes in the Great Plains and the Midwest, USA, for over 70 years.1 The research supporting its use as a pasture and conservation species was largely conducted by US Department of Agriculture (USDA) research programs, most notably the Agricultural Research Service (ARS) project located at the University of Nebraska-Lincoln and USDA Plant Materials Centers that are located throughout the United States. In this report, …

Identification Of A Second Asian Soybean Rust Resistance Gene In Hyuuga Soybean, Mandy D. Kendrick, Donna K. Harris, Bo-Keun Ha, D. L. Hyten, P. B. Cregan, Reid D. Frederick, H. Roger Boerma, Kerry F. Pedley

Department of Agronomy and Horticulture: Faculty Publications

Asian soybean rust (ASR) is an economically significant disease caused by the fungus Phakopsora pachyrhizi. The soybean genes Rpp3 and Rpp?(Hyuuga) confer resistance to specific isolates of the pathogen. Both genes map to chromosome 6 (Gm06) (linkage group [LG] C2). We recently identified 12 additional soybean accessions that harbor ASR resistance mapping to Gm06, within 5 centimorgans of Rpp3 and Rpp?(Hyuuga). To further characterize genotypes with resistance on Gm06, we used a set of eight P. pachyrhizi isolates collected from geographically diverse areas to inoculate plants and evaluate them for differential phenotypic responses. …

Mutational Analysis Of The Major Soybean Uref Paralogue Involved In Urease Activation, Joe C. Polacco, D. L. Hyten, Mônica Medeiros-Silva, David A. Sleper, Kristin D. Bilyeu

Department of Agronomy and Horticulture: Faculty Publications

The soybean genome duplicated ~14 and 45 million years ago and has many paralogous genes, including those in urease activation (emplacement of Ni and CO₂ in the active site). Activation requires the UreD and UreF proteins, each encoded by two paralogues. UreG, a third essential activation protein, is encoded by the single-copy Eu3, and eu3 mutants lack activity of both urease isozymes. eu2 has the same urease-negative phenotype, consistent with Eu2 being a single-copy gene, possibly encoding a Ni carrier. Unexpectedly, two eu2 alleles co-segregated with missense mutations in the chromosome 2 UreF paralogue (Ch02UreF), suggesting …

Cytokinin-Mediated Source ⁄Sink Modifications Improve Drought Tolerance And Increase Grain Yield In Rice Under Water-Stress, Zvi Peleg, Maria Reguera, Ellen Tumimbang, Harkamal Walia, Eduardo Blumwald

Department of Agronomy and Horticulture: Faculty Publications

Drought is the major environmental factor limiting crop productivity worldwide. We hypothesized that it is possible to enhance drought tolerance by delaying stress-induced senescence through the stress-induced synthesis of cytokinins in crop-plants. We generated transgenic rice (Oryza sativa) plants expressing an isopentenyltransferase (IPT) gene driven by PSARK, a stress- and maturation-induced promoter. Plants were tested for drought tolerance at two yield-sensitive developmental stages: pre- and post-anthesis. Under both treatments, the transgenic rice plants exhibited delayed response to stress with significantly higher grain yield (GY) when compared to wild-type plants. Gene expression analysis revealed a significant shift in expression of hormone-associated …

Western Australia's Biosecurity, Department Of Agriculture And Food, Western Australia, Department Of Environment And Conservation, Western Australia, Department Of Fisheries, Western Australia, Forest Products Commission, Western Australia

Biosecurity published reports

Biosecurity is the protection of the economy, environment and human health from the negative impacts of pests, weeds and diseases, including the management of invasive species if they become established (definition adopted by AusBIOSEC).

This requires steps to prevent the entry of harmful organisms, as well as the timely and efficient management of them if they do enter.

Biosecurity threats range from catastrophic diseases such as Foot and Mouth Disease, which causes rapid and widespread animal deaths, to more subtle and slower spreading problems such as invasive weeds, mussels that foul vessel hulls and fungus-induced dieback disease of trees. These …

Noxious Weed Control: 2011, Mike Moechnig, Leon J. Wrage, Darrell L. Deneke

SDSU Extension Fact Sheets

Noxious weeds are non-native plant species that are a concern to South Dakota land owners and managers. They can seriously impact the native plant community by altering or affecting agriculture, recreation, and wildlife.

Efficient And Stable Expression Of Gfp Through Wheat Streak Mosaic Virus-Based Vectors In Cereal Hosts Using A Range Of Cleavage Sites: Formation Of Dense Fluorescent Aggregates For Sensitive Virus Tracking, Satyanarayana Tatineni, Anthony J. Mcmechan, Gary L. Hein, Roy French

Department of Plant Pathology: Faculty Publications

A series of Wheat streak mosaic virus (WSMV)-based expression vectors were developed by engineering a cycle 3 GFP (GFP) cistron between P1 and HC-Pro cistrons with several catalytic/cleavage peptides at the Cterminus of GFP. WSMV-GFP vectors with the Foot-and-mouth disease virus 1D/2A or 2A catalytic peptides cleaved GFP from HC-Pro but expressed GFP inefficiently. WSMV-GFP vectors with homologous NIa-Pro heptapeptide cleavage sites did not release GFP from HC-Pro, but efficiently expressed GFP as dense fluorescent aggregates. However, insertion of one or two spacer amino acids on either side of NIb/CP heptapeptide cleavage site or deletion in HC-Pro cistron improved processing …

Another Really, Really Big Virus, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Viruses with genomes larger than 300 kb and up to 1.2 Mb, which encode hundreds of proteins, are being discovered and characterized with increasing frequency. Most, but not all, of these large viruses (often referred to as giruses) infect protists that live in aqueous environments. Bioinformatic analyses of metagenomes of aqueous samples indicate that large DNA viruses are quite common in nature and await discovery. One issue that is perhaps not appreciated by the virology community is that large viruses, even those classified in the same family, can differ significantly in morphology, lifestyle, and gene complement. This brief commentary, which …

Motus, Morphology, And Biodiversity Estimation: A Case Study Using Nematodes Of The Suborder Criconematina And A Conserved 18s Dna Barcode, Thomas O. Powers, Timothy Harris, Rebecca Higgins, Peter Mullin, Lisa Sutton, Kirsten Powers

Department of Plant Pathology: Faculty Publications

DNA barcodes are increasingly used to provide an estimate of biodiversity for small, cryptic organisms like nematodes. Nucleotide sequences generated by the barcoding process are often grouped, based on similarity, into molecular operational taxonomic units (MOTUs). In order to get a better understanding of the taxonomic resolution of a 3’ 592-bp 18S rDNA barcode, we have analyzed 100 MOTUs generated from 214 specimens in the nematode suborder Criconematina. Previous research has demonstrated that the primer set for this barcode reliably amplifies all nematodes in the Phylum Nematoda. Included among the Criconematina specimens were 25 morphologically described species representing 12 genera. …

Presence Of Fusarium Spp. In Air And Soil Associated With Sorghum Fields, Deanna L. Funnell-Harris, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

Sorghum grain, valuable for feed, food, and bioenergy, can be colonized by several Fusarium spp.; therefore, it was of interest to identify possible sources of conidia. Analysis of air and soil samples provided evidence for the presence of propagules from Fusarium genotypes that may cause grain infections. Soil population estimates of members of the Gibberella fujikuroi species complex, that includes sorghum pathogens and other Fusarium spp., suggested that adequate inoculum for systemic infections was present. Conidia in air samples within two sorghum fields were collected by passive trapping for 2 years. Subsampled Fusarium isolates indicated that numbers of G. fujikuroi …

First Report Of Goss's Bacterial Wilt And Leaf Blight (Clavibacter Michiganensis Subsp. Nebraskensis) Of Corn In Texas, K. A. Korus, A. D. Timmerman, R. D. French-Monar, T. A. Jackson

Department of Plant Pathology: Faculty Publications

In September 2009, the University of Nebraska–Lincoln Plant and Pest Diagnostic Clinic received leaf samples of hybrid corn (Zea mays L.) displaying long, necrotic lesions with wavy margins. The lesions had discontinuous water-soaked spots that are indicative of Goss's bacterial wilt and leaf blight. The symptomatic leaves were submitted from Dallam County, located in the Texas Panhandle (northwest Texas). According to the USDA Farm Service Agency and the National Agricultural Statistics Service, in 2009 Dallam County had 54,025 ha planted to corn. This is approximately 19% of the total corn planted in the 26 counties in the Texas Panhandle …