Digital Commons Network^™

Multi-Tactic Ecological Weed Management In A Changing Climate, Sonja K. Birthisel

Electronic Theses and Dissertations

Climate change is expected to impact weed communities in Maine, and the efficacy of tools and tactics farmers use to manage them. Through seedbank sampling and surveys of Maine organic farms, we identified currently rare weeds that are known to be especially abundant or problematic in warmer areas of the USA and might therefore represent an emerging agronomic risk. Many ecological weed management strategies that focus on depleting the weed seedbank are expected to remain effective in a changing climate, and become increasingly important as efficacy of cultivation and some herbicide applications diminish or become more variable. Through field experiments, …

Establishment Of Turfgrass From Seed And Sod In Sand Based Systems Combining Sprinkler And Subsurface Drip Irrigation Systems, Roshaan Ahmed Khan Niazi

Electronic Theses and Dissertations

The establishment of turfgrass using subsurface drip irrigation (SDI) in sand based media has limited success. However, it is unknown if starting with overhead (sprinkler) irrigation and transitioning to SDI can enhance turfgrass establishment. Two experiments were conducted at Stephen F. Austin State University (SFASU) to investigate the establishment of “L-93” creeping bentgrass (Agrostis stolonifera) from seed and “TifEagle” ultra dwarf hybrid bermudagrass (Cynodon dactylon x Cynodon transvaalensis) from sod using sand based media. Each experiment consisted of two trials conducted in summer 2017 and spring 2018. Both creeping bentgrass trials and the spring ultra dwarf …

Climatic Range Filling Of North American Trees, Benjamin Seliger

Electronic Theses and Dissertations

Understanding the degree to which species distributions are controlled by climate is crucial for forecasting biodiversity responses to climate change. Climatic equilibrium, when species are found in all places which are climatically suitable, is a fundamental assumption of species distribution models, but there is evidence in support of climate disequilibria in species ranges. Long-lived, sessile organisms such as trees may be especially vulnerable to being outpaced by climate change, and thus prone to disequilibrium. In this dissertation, I tested the degree to which North American trees are in equilibrium with their potential climatic ranges using the ‘range filling’ metric, which …

Bryophyte Assemblages On American Hornbeam (Carpinus Caroliniana) And The Surrounding Arboreal Communities Within The Forest Of East Texas, Cassey Edwards

Electronic Theses and Dissertations

The bryophytes, the non-vascular plants, include the mosses (Bryophyta with approximately 13,000 species), the liverworts (Marchantiophyta with approximately 5,000 species), and the hornworts (Anthocerotophyta with approximately 150 species). Initial observations indicated that the midstory tree Carpinus caroliniana Walter (American hornbeam) has a bryophyte composition with an unusually high diversity of leafy liverworts. Voucher samples were taken from the four intercardinal directions (Northeast, Northwest, Southwest, and Southeast) from six Carpinus trees and their nearest neighbor that was neither Pinus nor another Carpinus at each of six sites across East Texas. Percent coverage, species richness, Shannon’s diversity and Pielou’s evenness were computed. …

Sip-428, A Sir2 Deacetylase Enzyme And Its Role In Biotic Stress Signaling Pathway, Bal Krishna Chand Thakuri

Electronic Theses and Dissertations

SABP2 (Salicylic Acid Binding Protein 2) plays a vital role in the salicylic acid signaling pathway of plants both regarding basal resistance and systemic acquired resistance against pathogen infection. SIP-428 (SABP2 Interacting Protein-428) is a Silent information regulator 2 (SIR2) like deacetylase enzyme that physically interacts with SABP2 in a yeast two-hybrid interaction and confirmed independently by a GST pull-down assay. We demonstrated that SIP- 428 is an NAD+ dependent SIR2 deacetylase enzyme. Transgenic tobacco plants silenced in SIP- 428 expression via RNAi showed enhanced basal resistance to microbial pathogens. Moreover, these SIP-428-silenced lines also exhibited a robust induction of …

Localization Of Sip470, A Plant Lipid Transfer Protein In Nicotiana Tabacum, Shantaya Andrews

Electronic Theses and Dissertations

SABP2-interacting protein 470 (SIP470), a non-specific lipid transfer protein (nsLTP), was discovered in a yeast two-hybrid screening using SABP2 as bait and tobacco leaf proteins as prey. SABP2 is an important enzyme in systemic acquired resistance that converts salicylic acid to methyl salicylate. Localization studies are an important aspect to understanding the biological function of proteins. nsLTPs are generally considered apoplastic proteins and has been localized intracellularly and extracellularly. Transient expression shows highest expression of SIP470-eGFP at 2 days post infiltration into Nicotiana benthamiana. Confocal microscopy showed localization near the periphery of the cell. Subcellular localization using differential centrifugation showed …

Characterization Of Acyltransferases And Wrinkled Orthologs Involved In Tag Biosynthesis In Avocado, Md Mahbubur Rahman

Electronic Theses and Dissertations

Triacylglycerols (TAG) or storage oils in plants are utilized by humans for nutrition, production of biomaterials and fuels. Since nonseed tissues comprise the bulk biomass, it is pertinent to understand how to improve their TAG content. Typically, the final step in TAG biosynthesis is catalyzed by diacylglycerol (DAG) acyltransferases (DGAT) and/or phospholipid: diacylglycerol acyltransferases (PDAT), which also determine the content and composition of TAG. Besides enzymatic regulation of TAG synthesis, transcription factors such as WRINKLED1 (WRI1) play a critical role during fatty acid synthesis. In this study, mesocarp of Persea americana, with > 60% TAG by dry weight and oleic …

Breeding Bird Response To Post Oak Savanna Restoration Seven Years Post Management In Eastern Texas, Courtney Mcinnerney

Electronic Theses and Dissertations

Oak savannas were once an abundant vegetation type in the Midwestern United States that have now declined to <1% of their original distribution. Historically, natural disturbances such as periodic fire and grazing maintained oak savannas, but these have been reduced or eliminated, resulting in woody encroachment and subsequent habitat loss and degradation. In 2009-10, a baseline, pre-restoration study was completed to determine vegetation characteristics, breeding bird abundances, nest success, and nest site selection at the Gus Engeling Wildlife Management Area (GEWMA) in eastern Texas. The results showed a lack of savanna vegetation structure on degraded sites and few savanna or grassland obligate bird species. The goal of this study was to determine how breeding birds of oak savanna vegetation types in eastern Texas respond to restoration effects 7 years after initial management. Post-restoration surveys completed in 2016-17 showed a change in avian assemblages from a more woodland dominated community to grassland/savanna community. The presence and breeding of savanna obligate species dickcissel (Spiza americana) and lark sparrow (Chondestes grammacus) indicates that the restoration was successful. The presence of savanna species can be linked to the herbaceous vegetation that was restored to more closely resemble historic oak savanna structure and can quantify the success of restoration efforts.

Factors Affecting Survival And Carpogenic Germination Of Pseudosclerotia Of Monilinia Vaccinii-Corymbosi, The Causal Agent Of Mummy Berry, On Vaccinium Angustifolium In Maine, Tyler L. Case

Electronic Theses and Dissertations

The primary focus of this research project was to identify factors in the field affecting survival and the environmental conditions affecting carpogenic germination of pseudosclerotia of Monilinia vaccinii-corymbosi (MVC) which is a common fungal pathogen of lowbush blueberry (Vaccinium angustifolium) in Maine. The interactions between biological oranisms, such as fungi and insects with pseudosclerotia prior to and during the overwintering process were investigated in the research outlined below. Fungi from the surfaces of pseudosclerotia were screened as potential antagonists in a co-plate experiment. Most of the potentially antagonistic fungi tested reduced the width of the MVC reference cultures. These potential …

Propagation Of The Native North American Shrub Lonicera Villosa And Trait Comparisons With Nonnative Congeneric Taxa, Darren J. Hayes

Electronic Theses and Dissertations

The honeysuckles, or Lonicera, represent a circumboreally-distributed genus in the Caprifoliaceae family. A diverse assortment of vines, lianas, and shrubs comprise the genus, and honeysuckles have long been a staple of the horticultural industry, prized for their robustness as much as their sweet-scented flowers and colorful fruits. However, many cultivated honeysuckles of Eurasian origin have proven invasive outside of their native range, displacing native species and reducing overall diversity and ecosystem health. Planting of Eurasian Lonicera taxa is now often discouraged or banned throughout much of North America. Conversely, native North American Lonicera species are often sparsely distributed and …

Consumer Acceptance And Phytonutrient Assessment Of Cold Hardy, Locally Grown Plums, Amber L. Elwell

Electronic Theses and Dissertations

Prunus salicina, Japanese plums, and Prunus domestica, European plums, are naturally rich in fiber, minerals, vitamins and phytonutrients. Consuming plums can increase overall fruit intake and can be incorporated into part of a healthy diet. Through local plum production, harvesting can be completed without the need for cross-country shipping, which can increase overall acceptability and nutritional quality of the fruit. Furthermore, the increase in local production can help to boost Maine’s economy and creates a market for new plum product production.

The first objective of this study was to determine consumer acceptance of locally grown plum cultivars at a …

Flower Visitation In Relation To Pollen And Nectar Nutrition: Implications For Pollinator Habitat And Conservation, Megan E. Leach

Electronic Theses and Dissertations

Pollination of both wild and crop plants is at a crossroads; honey bee populations are experiencing losses at a higher rate than ever before, and some native bee species are declining in abundance to the point of being listed as endangered species. A few examples of these threats include pesticide exposure, habitat loss, and climate change. In response to bee population declines, conservation efforts have been initiated to increase habitat quality for bees by planting pollinator reservoirs or gardens. Plants provide nutrition to bees in the form of pollen and nectar. Several studies have shown links between higher nutritional quality …

Band-Sowing With Hoeing For Weed Management In Organic Grains, Margaret R. Mccollough

Electronic Theses and Dissertations

Weeds remain the foremost production challenge for organic small grain growers in the Northeastern United States. Instead of sowing crops in narrow, single-line rows, band-sowing with inter-band hoeing is a cropping strategy that could provide superior weed control. In theory, band-sowing suppresses weeds in the intra-band zone by improving the spatial arrangement of the crop from that of typical rows to a more uniform pattern within the planted bands, maximizing interspecific and reducing intraspecific competition. Weeds in the inter-band zone are controlled by cultivating with aggressive sweeps; tine harrowing can target weeds in the intra- and inter-band zones.

Chapter one …

Effect Of Pinching And Spacing On The Growth And Development Of Sunflowers (Helianthus Annuus) In East Texas, Bilawal Irshad Cheema

Electronic Theses and Dissertations

Helianthus annuus cultivars were grown in East Texas to evaluate the effect of pinching and spacing on their growth and development. The first experiment was conducted twice (Trial 1A, 28 April 2017 and Trial 1B, 3 August 2017) to evaluate the effect of pinching at nodes 1, 2, 3, and 4 on sunflower cultivars ‘Superior Gold’, ‘Pro Cut Gold’, ‘Sun Bright Supreme’, ‘Vincent’s Choice’, and ‘Sunrich Lemon’. For trial 1A, all the non-pinched treatments for the five cultivars produced marketable stem lengths, stem diameters, flower diameters, and disk diameters. For the cultivar ‘Superior Gold’ all the treatments produced marketable stems. …

Optimizing Fertilizer And Compost Rates In Organic Reduced Till Agriculture, Nicholas W. Rowley

Electronic Theses and Dissertations

Interest in reduced tillage systems has been increasing and advanced by a need to practice agriculture in a sustainable way to limit environmental degradation. The focus on preserving soil integrity has become commonplace in all scales of agriculture. Recently trends in agricultural production have given rise to numerous small farms centered on local and sustainable farming. In turn, this has led to a growing desire to implement conservation tillage into these systems.

In 2015 and 2016 a collaborative effort between the University of Maine at the Maine Agricultural and Forestry Experiment Station: Highmoor Farm and Cornell University at the Homer …

Reducing Tillage In Small-Scale Permanent Bed Organic Vegetable Production Systems, Jeremiah D. Vallotton

Electronic Theses and Dissertations

The response of field-grown vegetable crops to reduced tillage and mulching in permanent beds was evaluated through measuring crop yields, weed pressure, earthworm counts, and soil basal respiration. Two vegetable crops (“Bush Delicata” squash and “Farao” cabbage) were started in April and May of 2016 and 2017 respectively, transplanted in late June, and harvested on 15-Sep-2016 and 25-Aug-2017. Fruit number and weight of squash, and head weight and feeding damage of cabbage were measured. These results suggest that intensive tillage (8” rototill every year) can be successfully reduced to alternating years of shallow (2”) rototilling and a less intensive form …

Big Data For Small Parks: Examining Regional Vegetation Patterns To Assess The Current Condition And Vulnerability Of Eastern National Parks To Climate Change, Kathryn M. Miller

Electronic Theses and Dissertations

The United States National Park Service mission is to preserve natural and cultural resources unimpaired for future generations. Given climate change, the paradigm of restoring natural resources to their pre-European settlement condition is no longer appropriate or achievable management. Instead, we must promote resilience and plan for adaptation. This approach poses many challenges, including knowledge gaps about the current condition of park ecosystems including wetlands, and lack of information about the matrix surrounding parks, which will strongly influence park ecosystem response to climate change. My dissertation research focused on filling these knowledge gaps to provide much needed information to managers …

Soil Ecology Of The Exotic Dune Grass Leymus Arenarius., Matthew L. Reid

Electronic Theses and Dissertations

Exotic plants can alter the structure and function of native communities both above- and belowground, which is particularly important in primary successional sand dune ecosystems where plant-soil interactions are critical drivers of successional dynamics. In Great Lakes sand dunes, the native foundation grass Ammophila breviligulata dominates early in succession until an accumulation of detrimental soil organisms causes its die-back of the grasses. Die-back of this native foundation species can be slowed by mutualistic interactions between plants and mycorrhizal fungi. Changes to the plant community resulting from invasion, and subsequent effects on the soil community have the potential to disrupt the …

Tripartite Interactions Of Legumes With Arbuscular Mycorrhizal Fungi And Rhizobial Bacteria: Insight Into Plant Growth, Seed Yield, And Resource Exchange, Arjun Kafle

Electronic Theses and Dissertations

Under natural conditions, legumes, such as alfalfa (Medicago) and soybean (Glycine max) are colonized with arbuscular mycorrhizal (AM) fungi and rhizobial bacteria forming tripartite interactions. Legumes are important crop species due to their high nutritional and economic values. Most of the previous literatures focused on experiments with an individual symbiont: either AM fungi or rhizobial bacteria, but not with both symbionts at the same time, thus our current understanding of resource exchange in tripartite interactions is limited. It has been reported that AM fungi primarily provide phosphate (P), nitrogen (N), and other nutritional and non-nutritional benefits while rhizobial bacteria solely …

Map-Based Cloning And Molecular Characterization Of The Seed Dormancy 10 Locus In Rice (Oryza Sativa L.), Wirat Pipatpongpinyo

Electronic Theses and Dissertations

Seed dormancy is a key adaptive trait of both ecological and agricultural importance. Although many quantitative trait loci (QTL) have been associated with seed dormancy in cereal crops or model plants, a majority of them remain unknown for molecular identities and functions. Cereal crops and wild/weedy relatives usually have weak and strong seed dormancy, respectively, such as Asian cultivated rice vs. weedy rice (Oryza sativa L.). Previous research identified a set of seed dormancy QTL, including qSD10, in single plant-derived BC₁F₂ and BC₁F₃ populations from the backcross between the weedy rice line SS18-2 …

Regulation Of Local Auxin Metabolism During Soybean Nodule Development, Suresh Damodaran

Electronic Theses and Dissertations

Legume-rhizobia symbiosis leads to the development of secondary root organs called nodules. Rhizobia bacteria housed inside nodules assimilate atmospheric nitrogen and convert them into plant usable forms thereby reducing the need for fertilizer application in crop legumes like soybean. Nodule development is a coordinated process orchestrated by multiple plant hormones. In soybean, the auxin responsive gene expression was detected in nodule primordia and in the periphery of mature nodules, primarily in nodule vasculature. Auxin hypersensitivity reduces nodule formation in soybean and also polar auxin transport inhibition at the site of nodule development is not crucial for determinate nodule formation. Therefore, …

Measuring The Influence Of Bedding On Soil Nitrogen Losses And Corn Crop Nitrogen Characteristics For Fall Applied Solid Beef Cattle Manure In Eastern South Dakota, Mukesh Mehata

Electronic Theses and Dissertations

Nitrogen (N) is a major component of chlorophyll which plays a key role in the photosynthesis process in crops. The N is one of the highest demanded nutrients by all plants for their growth and reproduction. Manure or inorganic fertilizer is often applied to fulfill the crops’ N demand. However, the applied N sources have the potential of N losses in different forms from the soil volume in many ways such as ammonia (NH₃) volatilization, aerial nitrous oxide (N₂O) loss, nitrate (NO₃ --N) leaching, and runoff and/or erosion. Soil fertility, crop yield, water quality, and …

Impacts Of Diverse Crop Rotations And Integrated Crop-Livestock System On Soil Quality In South Dakota, Atilla Polat

Electronic Theses and Dissertations

Crop diversification can be beneficial in improving soil quality parameters. Diverse crop rotations and integrated crop-livestock systems (ICLS), are two examples of crop diversification used in this study to assess soil quality. The objectives of this study were to: (i) assess the impacts of diverse rotations on soil quality parameters, and (ii) assess the impacts of low and high stocking density on soil quality parameters. Both of the studies were conducted separately and are presented as two different chapters. To accomplish objective (i), a long-term experiment was selected which was established near Brookings, South Dakota, USA at USDA-ARS lab in …

Transcriptome Analysis Of Root Development In Wheat Triticum Aestivum Using High Throughtput Sequencing Technologies, Ghana Challa

Electronic Theses and Dissertations

Root provides plant water, nutrients and anchorage from soil. Most our knowledge of molecular mechanisms of root development is from the dicot model plant Arabidopsis, but very few studies have done in monocot crop systems like rice, maize, and wheat. We are studying very short root (VSR) phenotype in wheat, and lack of a sequenced reference genome in wheat prompted us to sequence and assemble the root transcriptome of the reference cultivar Chinese Spring (CS). A root transcriptome was assembled from the sequenced reads generated from root tip and the mature root tissues of CS. Approximately 169 million reads were …

Application Of Genomic Approaches To Improve Yield And Bacterial Leaf Streak Resistance In Winter Wheat, Sai Mukund Ramakrishnan

Electronic Theses and Dissertations

Global wheat production is threatened by the change in climate thus leading lead to the increase in the biotic and abiotic stresses. We need to increase wheat productivity at a faster pace and manage these challenges to meet the growing demand. Development of cultivars with durable disease resistance and enhancing the rate of genetic gain in wheat are the major goals in wheat breeding programs. Bacterial Leaf Streak (BLS) is one of the most threatening bacterial diseases to wheat in the US Northern Great Plains. Unlike fungal diseases, bacterial diseases cannot be effectively managed using chemicals and thus developing disease …

Microbial Communities And Their Impact On Bioenergy Crops In Dynamic Environments, Brandon Monier

Electronic Theses and Dissertations

Native perennial grasses, such as prairie cordgrass (PCG, Spartina pectinata Link), and switchgrass (SG, Panicum virgatum L.) have a great potential as bioenergy crops, because they require fewer inputs, produce more energy, and reduce greenhouse gas emissions in comparison to annual cropping systems such as corn and soybean. SG has been selected by the U.S. Department of Energy for development as bioenergy crop, but studies have shown that PCG can outcompete switchgrass in terms of biomass production. These crops can also form associations with a wide variety of plant growth promoting microbes including arbuscular mycorrhial (AM) fungi. In CHAPTER 2, …

Study Of Seasonal Change And Water Stress Condition In Plant Leaf Using Polarimetric Lidar Measurement, Prabeen Kattel

Electronic Theses and Dissertations

Study of vegetation is of great importance to the improvement of agriculture and forest management. Although there have been various attempts to characterize vegetation using remote sensing techniques, polarimetric lidar is a novel remote sensing tool that has shown potential in vegetation remote sensing. In this thesis, a near-infrared polarimetric lidar at 1064 nm was used to investigate the effects of seasonal change and water stress condition on plant leaves. Two variables, time and water content, affected the plant leaf laser depolarization ratio measurement. The first study focused on the maple tree in order to figure out how seasonal change …

Identification Of Qtl Modifying The Activity Of The Tcb1-S Locus And Characterization And Sequencing Of Two Plutonium-Beryllium Induced Reduced Gametophyte Transmission Mutants In Maize, Merritt Bryer Burch

Electronic Theses and Dissertations

This thesis is split into two independent projects both involving the male gametophyte generation of maize. The first project looks at how pollen interacts with the female gametophyte to reduce its transmission in cross-incompatible reactions controlled by the unilateral cross-incompatibility system, teosinte crossing barrier 1. The second project explores two plutonium-beryllium induced male gametophyte mutants and attempts to uncover their genetic basis.

Identification of QTL Modifying the Activity of the Tcb1-s Locus
Teosinte crossing barrier 1 (Tcb1) is a unilateral cross-incompatibility system present in maize that provides a pre-zygotic pistil barrier to plants carrying Tcb1-s (strong allele) from pollen …

Evaluation Of Alternative Weed Hosts And Management Strategies For Soybean Cyst Nematode In South Dakota, Pawan Basnet

Electronic Theses and Dissertations

The soybean cyst nematode (SCN; Heterodera glycines, Ichinohe) is an important pathogen of soybean in South Dakota which causes significant yield losses. SCN has been found in 30 South Dakota counties as on 2017 and is estimated to cause yield loss of 1.9 Metric tons (Mt) annually. SCN has diverse crop and weed hosts as it can reproduce in several crops and weeds. The presence of Heterodera glycines (HG) types can reduce the effectiveness of SCN-resistant cultivars and the HG types reproduction on weed hosts can negate the effectiveness of crop rotation by continued build-up in the field. This …

Improving The Nutritional Characteristics Of Plant Feedstuff By-Products Using Fungal Metabolism, Jacob Zahler

Electronic Theses and Dissertations

Plant feedstuff by-products such as soy processing wastewater, guar korma meal, and sorghum hominy are very different, however, all possess a rich nutrient profile. Lessening their value is the presence of lignocellulose, plant anti-nutritional factors, and unfavorable protein profiles. Fungal conversion processes are an attractive approach to improving the value of these by-products by degrading detrimental fractions of each while simultaneously creating nutrient-rich cell mass. The aim of this research was to improve the value of each by-product for potential application in monogastric diets such as fish. Fungal organisms, both yeast and filamentous fungi, were examined for their ability to …