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Drivers Of Post-Fire Vascular Plant Regeneration In The Conifer-Dominated Boreal Forest Of Southern Northwest Territories, Alison White

Theses and Dissertations (Comprehensive)

In recent years, climate warming has led to an increase in the severity and frequency of naturally occurring fires in boreal ecosystems globally. In 2014, an unprecedented 3.4 million hectares of boreal forest burned in the Northwest Territories (NWT). While much research has focused on post-fire succession of serotinous tree species such as Picea mariana (black spruce) and Pinus banksiana (jack pine), the understory community of vascular plants play an important role in ecosystem functioning but less is known about the response of this component of the system to changing fire regimes. Regeneration strategies such as the ability to resprout …

Push-Pull Farming System Controls Fall Armyworm: Lessons From Africa, Zeyaur R. Khan, Jimmy O. Pittchar, Charles A.O. Midega, John A. Pickett

All Peer-Reviewed Publications

Fall armyworm (FAW) Spodoptera frugiperda invaded Africa, with the first detections being reported in Central and Western Africa in early 2016, and now affects at least 40 countries in Africa, causing up to total crop loss amounting to over $6.2 billion p.a. FAW is an invasive polyphagous pest that causes damage to economically important crops and has recently been reported in the Indian sub-continent. Effective control of FAW through use of synthetic chemical pesticides and genetically modified crops such as Bt maize faces challenges including improper use, unaffordability by smallholder farmers and development of resistance by the pest. Additionally, dispersal …

Characterization Of Palmitoyltransferase Proteins In Arabidopsis Thaliana, Danielle Mcginty

Honors Theses and Capstones

No abstract provided.

Sown Forb Performance In Cp42 Fields, Nathan Theel, Mark Sherrard

Undergraduate Student Work

CP42 is a general conservation practice that attempts to establish pollinator-friendly habitat

In total, >500,000 acres have been converted to CP42 (>40% of which is in Iowa) [1]

To date, there has been no formal assessment of practice success (i.e., post-seeding forb establishment)

In this study, we assess forb establishment in randomly selected CP42 fields near Cedar Falls, Iowa

We identify forbs with high/low establishment and relate this to seed cost in an effort to improve seed mix design

Floral Resource Dynamics For Pollinators In A Central Iowa Tallgrass Prairie Restoration, Lily Conrad, Ben Hoksch, Mark C. Myers

Undergraduate Student Work

Recently, native and managed colonies of pollinators, including bees, butterflies, and other insects, have experienced a largescale declines. In an effort to restore habitat for pollinators, the United States Department of Agriculture’s Farm Service Agency (FSA) created the CP-42 Pollinator Habitat conservation practice under the Conservation Reserve Program. This program pays private landowners to restore habitat for pollinator species with ecological and economic importance. To qualify for the program, CP-42 seed mixes must include:

• A minimum of 9 pollinator-friendly flowering plants,

• A minimum of three species in bloom during each of three seasonal periods (April-June 15, June 15-July, …

Prairie Restoration Series: Recognizing And Appreciating Tallgrass Prairie Remnants, Greg Houseal

Tallgrass Prairie Publications and Reports

Prairie remnants are fragments of the original prairie landscape with their native plant communities still intact. Typically, this means soils were never plowed, graded, or buried by fill. Original prairie is meant to imply that populations of species have persisted or regenerated themselves on site through time (i.e., not planted by people as in prairie reconstruction). Some sites may have had brief soil disturbance in the past, for example, grading to create railroad beds in the 1800s, or fields that were cultivated for brief periods then abandoned. The key point regarding remnants is that some component of the original native …

Prairie Restoration Series: Seeding, Dave Williams

Tallgrass Prairie Publications and Reports

Deciding when to plant a prairie is a challenge. Some species establish better when spring-planted, other species establish better when fall-planted and some species are hard to establish whenever they are planted. Seeding rates of some species may need to be increased depending on when and how they are planted.

Prairie seed can be planted by broadcast seeding, hydroseeding, and drill seeding. Regardless of the seeding method used, it is essential that seed be planted at the proper depth and with good seed-to-soil contact.

The Effects Of Nutrient Resorption, Photosynthetic Rate, And Leaf Longevity On The Success Of Typha × Glauca, Clarissa Marie Ruiz

Dissertations and Theses @ UNI

The hybrid cattail Typha × glauca is invasive in the Midwestern United States, and outcompetes wetland natives and its parent species, Typha angustifolia and Typha latifolia under high nutrient conditions. Typha × glauca’s large size and copious litter production are the main factors known to contribute to its success, although research is lacking on physiological processes that contribute to its nitrogen use efficiency.

Nitrogen resorption was investigated as a mechanism of dominance in Typha × glauca. Due to nitrogen resorption being a nutrient conservation strategy, nitrogen resorption should be high in areas of low nitrogen availability. Since nitrogen …

Caterpillar/Basil-Plant Tandems, Paco Calvo

Animal Sentience

According to Reber (2016), subjectivity springs from primitive life itself. Granting his non-neurocentric stance, I shall try to show that his framework falls prey to zoocentric preconceptions that divest certain non-animal life-forms of mentality. There is no reason to exclude the possibility that plants have evolved different structures that underlie their own subjective experiences, all according to Reber’s model. It is the degree of phenotypic flexibility and integration that we observe in the behavioral repertoire of plants that may end up supporting their capacity for subjective experience. This remains an open empirical question.

Remobilization Of Heavy Metals By Mangrove Leaves, Hanan Almahasheer, Oscar Serrano, Carlos M. Duarte, Xabier Irigoien

Research outputs 2014 to 2021

Several studies have been carried out on heavy metal pollution in mangrove ecosystems. However, the role of mangroves in heavy metal remobilization is still relatively unknown. On one side, mangrove woody organs and soils sequester heavy metals for long time periods, but on the other hand, senescence of mangrove leaves may return these metals collected by roots to the upper layers of the soil. Here, we analyzed the concentration of chemical elements (Al, As, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sr, V, and Zn) as a function of age in mangrove leaves to understand heavy metals retention by …

Mary Agnes Chase, James P. Smith Jr

Botanical Studies

No abstract provided.

Reactive Oxygen Species Metabolism And Plant-Fungal Interactions, Lauren M. Segal, Richard A. Wilson

Department of Plant Pathology: Faculty Publications

Fungal interactions with plants can involve specific morphogenetic developments to access host cells, the suppression of plant defenses, and the establishment of a feeding lifestyle that nourishes the colonizer often—but not always—at the expense of the host. Reactive oxygen species (ROS) metabolism is central to the infection process, and the stage-specific production and/or neutralization of ROS is critical to the success of the colonization process. ROS metabolism during infection is dynamic—sometimes seemingly contradictory—and involves endogenous and exogenous sources. Yet, intriguingly, molecular decision-making involved in the spatio-temporal control of ROS metabolism is largely unknown. When also considering that ROS demands are …

Clean Low-Biomass Procedures And Their Application To Ancient Ice Core Microorganisms, Zhi-Ping Zhong, Natalie E. Solonenko, Maria C. Gazitua, Donald V. Kenny, Ellen Mosley-Thompson, Virginia I. Rich, James L. Van Etten, Lonnie G. Thompson, Matthew B. Sullivan

Department of Plant Pathology: Faculty Publications

Microorganisms in glacier ice provide tens to hundreds of thousands of years archive for a changing climate and microbial responses to it. Analyzing ancient ice is impeded by technical issues, including limited ice, low biomass, and contamination. While many approaches have been evaluated and advanced to remove contaminants on ice core surfaces, few studies leverage modern sequencing to establish in silico decontamination protocols for glacier ice. Here we sought to apply such “clean” sampling techniques with in silico decontamination approaches used elsewhere to investigate microorganisms archived in ice at ~41 (D41, ~20,000 years) and ~49 m (D49, ~30,000 years) depth …

Wheat Streak Mosaic Virus: A Century Old Virus With Rising Importance Worldwide, Khushwant Singh, Stephen N. Wegulo, Anna Skoracka, Jiban Kumar Kundu

Department of Plant Pathology: Faculty Publications

Wheat streak mosaic virus (WSMV) causes wheat streak mosaic, a disease of cereals and grasses that threatens wheat production worldwide. It is a monopartite, positive-sense, single-stranded RNA virus and the type member of the genus Tritimovirus in the family Potyviridae. The only known vector is the wheat curl mite (WCM, Aceria tosichella), recently identified as a species complex of biotypes differing in virus transmission. Low rates of seed transmission have been reported. Infected plants are stunted and have a yellow mosaic of parallel discontinuous streaks on the leaves. In the autumn, WCMs move from WSMV-infected volunteer wheat and other grass …

Waste Not, Want Not: Using Source-Separated Urine To Cultivate Maize In The Southern Highlands, Tanzania, Lucy Hatfield

Dissertations, Master's Theses and Master's Reports

In Sub-Saharan African countries, soil fertility is low due to unsustainable agricultural practices and little to no access to chemical fertilizer. Poor yields have resulted in many of these countries struggling to produce enough food to feed their growing populations. Human urine has been used as an effective, low-cost alternative to chemical fertilizers in greenhouse and plot trials on a variety of vegetables, but its effects on elemental grain composition in cereal crops are largely unknown. Here we tested whether diluted human urine applied as a fertilizer can increase maize crop growth, yield and nutritional content on small family-owned plots. …

Agroforestry Standards For Regenerative Agriculture [Review], Craig R. Elevitch, D. Niki Mazaroli, Diane Ragone

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Agroforestry is increasingly being recognized as a holistic food production system that can have numerous significant environmental, economic, and social benefits. This growing recognition is paralleled in the USA by the budding interest in regenerative agriculture and motivation to certify regenerative practices. Current efforts to develop a regenerative agriculture certification offer an opportunity to consider agroforestry’s role in furthering regenerative goals. To understand this opportunity, we first examine how agroforestry practices can advance regenerative agriculture’s five core environmental concerns: soil fertility and health, water quality, biodiversity, ecosystem health, and carbon sequestration. Next, we review a subset of certification programs, standards, …

Science At Engineer Cantonment, Hugh H. Genoways, Brett C. Ratcliffe, Carl R. Falk, Thomas E. Labedz, Paul R. Picha, John R. Bozell

University of Nebraska State Museum: Mammalogy Papers

Conclusions

It is our contention that Thomas Say, Titian Peale, Edwin James, and their colleagues of the Stephen Long Expedition of 1819–1820 were heavily engaged in scientific research, which took the form of the first biodiversity inventory undertaken in the United States. This accomplishment has been overlooked both by biologists and historians, but it should rank among the most significant accomplishments of the expedition. The results of this inventory continue to inform us today about environmental, faunal, and floral changes along the Missouri River in an area that is known to be an ecotone between the deciduous forests of the …

Historical Observations And Identifications Of Plants And Animals In The Vicinity Of Engineer Cantonment In 1819-1820, Hugh H. Genoways, Brett C. Ratcliffe, Carl R. Falk, John R. Bozell

University of Nebraska State Museum: Mammalogy Papers

Historical observations and identifications of plants and animals in the vicinity of Engineer Cantonment in 1819–1820 (James 1822) are shown below in Roman and Roman italic print. Specimens identified through phytoarcheological and zooarcheological analysis of materials and believed to be reasonably associated or contemporaneous with the Long Expedition use of the site (AU4) are shown in boldface. Species present in both the historical and archeological data are marked by an asterisk (*). References used in this compilation include Benedict (1996), Brewer (1970 [1840]), Conant and Collins (1991), Ducey (2000), Evans (1997), Falk et al. (this volume), Genoways et al. (2008), …

Sifting And Winnowing: Analysis Of Farmer Field Data For Soybean In The Us North-Central Region, Spyridon Mourtzinis, Juan I. Rattalino Edreira, Patricio Grassini, Adam C. Roth, Shaun N. Casteel, Ignacio A. Ciampitti, Hans J. Kandel, Peter M. Kyveryga, Mark A. Licht, Laura E. Lindsey, Daren S. Mueller, Emerson D. Nafziger, Seth L. Naeve, Jordan Stanley, Michael J. Staton, Shawn P. Conley

Department of Agronomy and Horticulture: Faculty Publications

Field trials are commonly used to estimate the effects of different factors on crop yields. In the present study, we followed an alternative approach to identify factors that explain field-to-field yield variation, which consisted of farmer survey data, a spatial framework, and multiple statistical procedures. This approach was used to identify management factors with strongest association with on-farm soybean yield variation in the US North Central (NC) region. Field survey data, including yield and management information, were collected over two crop growing seasons (2014 and 2015) from rainfed and irrigated soybean fields (total of 3568 field-year observations). Fields were grouped …

Genome-Wide Association Study For Identification And Validation Of Novel Snp Markers For Sr6 Stem Rust Resistance Gene In Bread Wheat, Amira M. I. Mourad, Ahmed Sallam, Vikas Belamkar, Stephen N. Wegulo, Robert Bowden, Yue Jin, Ezzat Mahdy, Bahy Bakheit, Atif A. El-Wafaa, Jesse Poland, Peter S. Baenziger

Department of Agronomy and Horticulture: Faculty Publications

Stem rust (caused by Puccinia graminis f. sp. tritici Erikss. & E. Henn.), is a major disease in wheat (Triticum aestivium L.). However, in recent years it occurs rarely in Nebraska due to weather and the effective selection and gene pyramiding of resistance genes. To understand the genetic basis of stem rust resistance in Nebraska winter wheat, we applied genome-wide association study (GWAS) on a set of 270 winter wheat genotypes (A-set). Genotyping was carried out using genotyping-by-sequencing and ~35,000 high-quality SNPs were identified. The tested genotypes were evaluated for their resistance to the common stem rust race in …

Can Bangladesh Produce Enough Cereals To Meet Future Demand?, J. Timsina, J. Wolf, N. Guilpart, L.G.J. Van Bussel, P. Grassini, J. Van Wart, A. Hossain, H. Rashid, S. Islam, M.K. Van Ittersum

Department of Agronomy and Horticulture: Faculty Publications

Bangladesh faces huge challenges in achieving food security due to its high population, diet changes, and limited room for expanding cropland and cropping intensity. The objective of this study is to assess the degree to which Bangladesh can be self-sufficient in terms of domestic maize, rice and wheat production by the years 2030 and 2050 by closing the existing gap (Yg) between yield potential (Yp) and actual farm yield (Ya), accounting for possible changes in cropland area. Yield potential and yield gaps were calculated for the three crops using well-validated crop models and site-specific weather,management and soil data, and upscaled …

Doublethink And Scale Mismatch Polarize Policies For An Invasive Tree, Caleb P. Roberts, Daniel R. Uden, Craig R. Allen, Dirac L. Twidwell Jr.

Department of Agronomy and Horticulture: Faculty Publications

Mismatches between invasive species management policies and ecological knowledge can lead to profound societal consequences. For this reason, natural resource agencies have adopted the scientifically-based density-impact invasive species curve to guide invasive species management. We use the density-impact model to evaluate how well management policies for a native invader (Juniperus virginiana) match scientific guidelines. Juniperus virginiana invasion is causing a sub-continental regime shift from grasslands to woodlands in central North America, and its impacts span collapses in endemic diversity, heightened wildfire risk, and crashes in grazing land profitability. We (1) use land cover data to identify the stage …

Managing Grazing Lands To Improve Soils And Promote Climate Change Adaptation And Mitigation: A Global Synthesis, Marcia Delonge, Andrea D. Basche

Department of Agronomy and Horticulture: Faculty Publications

The potential to improve soils to help farmers and ranchers adapt to and mitigate climate change has generated significant enthusiasm. Within this discussion, grasslands have surfaced as being particularly important, due to their geographic range, their capacity to store substantial quantities of carbon relative to cultivated croplands and their potential role in mitigating droughts and floods. However, leveraging grasslands for climate change mitigation and adaptation will require a better understanding of how farmers and ranchers who rely on them for their livelihoods can improve management and related outcomes. To investigate opportunities for such improvements, we conducted a meta-analysis of field …

Quantifying Variance Across Spatial Scales As Part Of Fire Regime Classifications, Rheinhardt Scholtz, Samuel D. Fuhlendorf, Sherry A. Leis, Joshua J. Picotte, Dirac L. Twidwell Jr

Department of Agronomy and Horticulture: Faculty Publications

The emergence of large-scale fire classifications and products informed by remote sensing data has enabled opportunities to include variability or heterogeneity as part of modern fire regime classifications. Currently, basic fire metrics such as mean fire return intervals are calculated without considering spatial variance in a management context. Fire return intervals are also only applicable at a particular grain size (defined as the spatial unit of interest) even though they are typically applied homogeneously. In this study, we utilized a 29-yr fire occurrence database to show how spatial variance changes with respect to grain as postulated by Wiens (1989) when …

Social–Ecological Landscape Patterns Predict Woody Encroachment From Native Tree Plantings In A Temperate Grassland, Victoria M. Donovan, Jessica L. Burnett, Christine H. Bielski, Hannah E. Birge, Rebecca Bevans, Dirac L. Twidwell Jr, Craig R. Allen

Department of Agronomy and Horticulture: Faculty Publications

Afforestation is often viewed as the purposeful planting of trees in historically non-forested grasslands, but an unintended consequence is woody encroachment, which should be considered part of the afforestation process. In North America’s temperate grassland biome, Eastern redcedar (Juniperus virginiana L.) is a native species used in tree plantings that aggressively invades in the absence of controlling processes. Cedar is a well-studied woody encroacher, but little is known about the degree to which cedar windbreaks, which are advocated for in agroforestry programs, are contributing to woody encroachment, what factors are associated with cedar spread from windbreaks, nor where encroachment …

Optimising The Identification Of Causal Variants Across Varying Genetic Architectures In Crops, Chenyong Miao, Jinliang Yang, James C. Schnable

Department of Agronomy and Horticulture: Faculty Publications

Association studies use statistical links between genetic markers and the phenotype variation across many individuals to identify genes controlling variation in the target phenotype. However, this approach, particularly conducted on a genome-wide scale (GWAS), has limited power to identify the genes responsible for variation in traits controlled by complex genetic architectures. In this study, we employ real-world genotype datasets from four crop species with distinct minor allele frequency distributions, population structures and linkage disequilibrium patterns. We demonstrate that different GWAS statistical approaches provide favourable trade-offs between power and accuracy for traits controlled by different types of genetic architectures. FarmCPU provides …

Maize Genomes To Fields: 2014 And 2015 Field Season Genotype, Phenotype, Environment, And Inbred Ear Image Datasets, Naser Alkhalifah, Darwin A. Campbell, Celeste M. Falcon, Jack M. Gardiner, Nathan D. Miller, Maria Cinta Romay, Ramona Walls, Renee Walton, Cheng-Ting Yeh, Martin Bohn, Jessica Bubert, Edward S. Buckler, Ignacio Ciampitti, Sherry Flint-Garcia, Michael A. Gore, Christopher Graham, Candice Hirsch, James B. Holland, David Hooker, Shawn Kaeppler, Joseph Knoll, Nick Lauter, Elizabeth C. Lee, Aaron Lorenz, Jonathan P. Lynch, Stephen P. Moose, Seth C. Murray, Rebecca Nelson, Torbert Rocheford, Oscar Rodriguez, James C. Schnable, Brian Scully, Margaret Smith, Nathan Springer, Peter Thomison, Mitchell Tuinstra, Randall J. Wisser, Wenwei Xu, David Ertl, Patrick S. Schnable, Natalia De Leon, Edgar P. Spalding, Jode Edwards, Carolyn J. Lawrence-Dill

Department of Agronomy and Horticulture: Faculty Publications

Objectives: Crop improvement relies on analysis of phenotypic, genotypic, and environmental data. Given large, well-integrated, multi-year datasets, diverse queries can be made: Which lines perform best in hot, dry environments? Which alleles of specific genes are required for optimal performance in each environment? Such datasets also can be leveraged to predict cultivar performance, even in uncharacterized environments. The maize Genomes to Fields (G2F) Initiative is a multi-institutional organization of scientists working to generate and analyze such datasets from existing, publicly available inbred lines and hybrids. G2F’s genotype by environment project has released 2014 and 2015 datasets to the public, with …

Phosphate Deficiency Negatively Affects Early Steps Of The Symbiosis Between Common Bean And Rhizobia, Mariel C. Isidra-Arellano, Maria Del Rocio Reyero-Saavedra, Maria Del Socorro Sanchez-Correa, Lise Pingault, Sidharth Sen, Trupti Joshi, Lourdes Girard, Norma A. Castro-Guerrero, David G. Mendoza-Cozatl, Marc Libault, Oswaldo Valdes-Lopez

Department of Agronomy and Horticulture: Faculty Publications

Phosphate (Pi) deficiency reduces nodule formation and development in different legume species including common bean. Despite significant progress in the understanding of the genetic responses underlying the adaptation of nodules to Pi deficiency, it is still unclear whether this nutritional deficiency interferes with the molecular dialogue between legumes and rhizobia. If so, what part of the molecular dialogue is impaired? In this study, we provide evidence demonstrating that Pi deficiency negatively affects critical early molecular and physiological responses that are required for a successful symbiosis between common bean and rhizobia. We demonstrated that the infection thread formation and the expression …

Intragenic Meiotic Crossovers Generate Novel Alleles With Transgressive Expression Levels, Sanzhen Liu, James C. Schnable, Alina Ott, Cheng-Ting Yeh, Nathan M. Springer, Jianming Yu, Gary Muehlbauer, Marja C. P. Timmermans, Michael J. Scanlon, Patrick S. Schnable

Department of Agronomy and Horticulture: Faculty Publications

Meiotic recombination is an evolutionary force that generates new genetic diversity upon which selection can act. Whereas multiple studies have assessed genome-wide patterns of recombination and specific cases of intragenic recombination, few studies have assessed intragenic recombination genome-wide in higher eukaryotes. We identified recombination events within or near genes in a population of maize recombinant inbred lines (RILs) using RNA-sequencing data. Our results are consistent with case studies that have shown that intragenic crossovers cluster at the 5' ends of some genes. Further, we identified cases of intragenic crossovers that generate transgressive transcript accumulation patterns, that is, recombinant alleles displayed …

Genome-Wide Association Study Reveals Novel Genomic Regions For Grain Yield And Yield-Related Traits In Drought-Stressed Synthetic Hexaploid Wheat, Madhav Bhatta, Alexey Morgounov, Vikas Belamkar, P. Stephen Baenziger

Department of Agronomy and Horticulture: Faculty Publications

Synthetic hexaploid wheat (SHW; 2n = 6x = 42, AABBDD, Triticum aestivum L.) is produced from an interspecific cross between durum wheat (2n = 4x = 28, AABB, T. turgidum L.) and goat grass (2n = 2x = 14, DD, Aegilops tauschii Coss.) and is reported to have significant novel alleles-controlling biotic and abiotic stresses resistance. A genome-wide association study (GWAS) was conducted to unravel these loci [marker–trait associations (MTAs)] using 35,648 genotyping-by-sequencing-derived single nucleotide polymorphisms in 123 SHWs. We identified 90 novel MTAs (45, 11, and 34 on the A, B, and D …