Botany Commons^™

Cover Crops And Corn Residue Removal: Impacts On Soil Hydraulic Properties And Their Relationships With Carbon, Michael Sindelar, Humberto Blanco-Canqui, Virginia L. Jin, Richard B. Ferguson

Department of Agronomy and Horticulture: Faculty Publications

Large-scale crop residue removal may negatively affect soil water dynamics. Integrating cover crop (CC) with crop residue management can be a strategy to offset potential adverse effects of residue removal. We studied: (i) the impact of corn (Zea mays L.) residue removal (56%) with and without the use of winter rye (Secale cereale L.) CC on soil hydraulic properties, (ii) whether CC would ameliorate residue removal effects on hydraulic properties, and (iii) relationships of hydraulic properties with soil organic C (SOC) and other properties under irrigated no-till continuous corn on a silt loam in south central Nebraska after …

Predicting Longitudinal Traits Derived From High-Throughput Phenomics In Contrasting Environments Using Genomic Legendre Polynomials And B-Splines, Mehdi Momen, Malachy T. Campbell, Harkamal Walia, Gota Morota

Department of Agronomy and Horticulture: Faculty Publications

Recent advancements in phenomics coupled with increased output from sequencing technologies can create the platform needed to rapidly increase abiotic stress tolerance of crops, which increasingly face productivity challenges due to climate change. In particular, high-throughput phenotyping (HTP) enables researchers to generate large-scale data with temporal resolution. Recently, a random regression model (RRM) was used to model a longitudinal rice projected shoot area (PSA) dataset in an optimal growth environment. However, the utility of RRM is still unknown for phenotypic trajectories obtained from stress environments. Here, we sought to apply RRM to forecast the rice PSA in control and water-limited …

Dedicated Bioenergy Crops And Water Erosion, Bharat Sharma Acharya, Humberto Blanco-Canqui, Robert B. Mitchell, Richard Cruse, David Laird

Department of Agronomy and Horticulture: Faculty Publications

Information on the water quality impact of perennial warmseason grasses (WSGs) when grown in marginal lands as dedicated energy crops is limited. We studied how WSGs affected runoff, sediment, and nutrient losses and related near-surface soil properties to those of no-till corn (Zea mays L.) on an eroded soil in southwestern Iowa and a center pivot corner in east-central Nebraska. The experiment at the eroded soil was established in 2012, and treatments included ‘Liberty’ switchgrass (Panicum virgatum L.) and no-till continuous corn. The experiment at the pivot corner was established in 2013 with ‘Liberty’ switchgrass, ‘Shawnee’ switchgrass, low-diversity grass …

Shifting Avian Spatial Regimes In A Changing Climate, Caleb P. Roberts, Craig R. Allen, David G. Angeler, Dirac Twidwell

Department of Agronomy and Horticulture: Faculty Publications

In the present era of rapid global change, development of early warnings of ecological regime shifts is a major focus in ecology. Identifying and tracking shifts in spatial regimes is a new approach with potential to enhance understanding of ecological responses to global change. Here, we show strong directional non-stationarity of spatial regimes identified by avian community body mass data. We do this by tracking 46 years of avian spatial regime movement in the North American Great Plains. The northernmost spatial regime boundary moved >590 km northward, and the southernmost boundary moved >260 km northward. Tracking spatial regimes affords decadal …

Rapid Metabolism Increases The Level Of 2,4-D Resistance At High Temperature In Common Waterhemp (Amaranthus Tuberculatus), Chandrima Shyam, Amit J. Jhala, Greg Kruger, Mithila Jugulam

Department of Agronomy and Horticulture: Faculty Publications

Common waterhemp emerges throughout the crop growing season in the Midwestern United States, and as a result, the seedlings are exposed to a wide range of temperature regimes. Typically, 2,4-D is used in the Midwest to control winter annual broad-leaf weeds before planting soybean and in an early post-emergence application in corn and sorghum; however, the evolution of 2,4-D-resistant common waterhemp in several Midwestern states may limit the use of 2.4-D for controlling this problem weed. Moreover, temperature is one of the crucial factors affecting weed control efficacy of 2,4-D. This research investigated the effect of temperature on efficacy of …

The Mitochondrial Genome Of Eleusine Indica And Characterization Of Gene Content Within Poaceae, Nathan D. Hall, Hui Zhang, Jeffrey P. Mower, Joseph Scott Mcelroy, Leslie R. Goertzen

Department of Agronomy and Horticulture: Faculty Publications

Plant mitochondrial (mt) genome assembly provides baseline data on size, structure, and gene content, but resolving the sequence of these large and complex organelle genomes remains challenging due to fragmentation, frequent recombination, and transfers of DNA from neighboring plastids. Themt genome for Eleusine indica (Poaceae: goosegrass) is comprehensibly analyzed here, providing key reference data for an economically significant invasive species that is also the maternal parent of the allotetraploid crop Finger millet (Eleusine coracana). The assembled E. indica genome contains 33 protein coding genes, 6 rRNA subunits, 24 tRNA, 8 large repetitive regions 15 kb of transposable elements across a …

Adaptation Of Photosynthesis To Water Deficit In The Reproductive Phase Of A Maize (Zea Mays L.) Inbred Line, H.F. Zheng, L.F. Xin, J.M. Guo, J. Mao, X.P. Han, L. Jia, B.Y. Zheng, C.G. Du, Roger W. Elmore, Q.H. Yang, R.X. Shao

Department of Agronomy and Horticulture: Faculty Publications

Photosynthesis is sensitive to water deficit (WD) stress. Maize (Zea mays L.) yield is vulnerable to water stress, especially if it occurs during the reproductive stage. In this study, the expression patterns of photosynthesis-related genes, together with photosynthetic gas-exchange and fluorescence parameters were investigated in a maize inbred line exposed to 50% of field water capacity (moderate WD) for 15 d after tassel emergence. The results demonstrated that WD down-regulated expression of psbA, psbB, psbC, psbP, psaA, psaB, and cab, especially at later periods of WD stress. Besides, with the increased WD stress, the steady decline in the value of …

United States Midwest Soil And Weather Conditions Influence Anaerobic Potentially Mineralizable Nitrogen, Jason D. Clark, Kristen S. Veum, Fabian G. Fernandez, James J. Camberato, Paul R. Carter, Richard B. Ferguson, David W. Franzen, Daniel E. Kaiser, Newell R. Kitchen, Carrie A. M. Laboski, Emerson D. Nafziger, Carl J. Rosen, John E. Sawyer, John F. Shanahan

Department of Agronomy and Horticulture: Faculty Publications

Nitrogen provided to crops through mineralization is an important factor in N management guidelines. Understanding of the interactive effects of soil and weather conditions on N mineralization needs to be improved. Relationships between anaerobic potentially mineralizable N (PMN_an) and soil and weather conditions were evaluated under the contrasting climates of eight US Midwestern states. Soil was sampled (0–30 cm) for PMN_an analysis before pre-plant N application (PP_0N) and at the V5 development stage from the pre-plant 0 (V5_0N) and 180 kg N ha−1 (V5_180N) rates and incubated for 7, 14, and …

Evaluation Of Spray Pattern Uniformity Using Three Unique Analyses As Impacted By Nozzle, Pressure, And Pulse-Widthmodulation Duty Cycle, Thomas R. Butts, Joe D. Luck, Bradley K. Fritz, W. Clint Hoffmann, Greg R. Kruger

Department of Agronomy and Horticulture: Faculty Publications

BACKGROUND: The increasing popularity of pulse-width modulation (PWM) sprayers requires that application interaction effects on spray pattern uniformity be completely understood to maintain a uniform overlap of spray, thereby reducing crop injury potential andmaximizing coverage on target pests. The objective of this researchwas to determine the impacts of nozzle type (venturi vs. non-venturi), boom pressure, and PWMduty cycle on spray pattern uniformity. Research was conducted using an indoor spray patternator located at the University of Nebraska-Lincoln in Lincoln, NE, USA. Coefficient of variation (CV), root mean square error (RMSE), and average percent error (APE) were used to characterize spray pattern …

Competition Or Facilitation: Examination Of Interactions Between Endangered Sida Hermaphrodita And Invasive Phragmites Australis, Samantha N. Mulholland

Theses and Dissertations (Comprehensive)

Virginia Mallow (Sida hermaphrodita) is a perennial herb of the Malvaceae family that is native to riparian habitats in northeastern North America. Throughout most of its geographical distribution however, it is considered threatened and only two populations are known from Canada. The biology and ecology of S. hermaphrodita are still poorly understood and although few studies have been performed to determine the factors that contribute to the species rarity, it is considered threatened potentially due to the loss of habitat caused by exotic European Common reed (Phragmites australis subsp. australis) invasion. Allelopathic and phytotoxic conditioning of …

Going Back To The Soil: An Integrated Approach To Farming., Renée V. Christie

Theses and Dissertations (Comprehensive)

Agricultural productivity is often constrained by nutrient availability; as such, copious amounts of synthetic fertilizers are applied to maintain productivity. However, the intensive use of synthetic fertilizers has reduced the capacity of the soil to carry out crucial roles such as nutrient cycling because of shifts in the microbial community composition and structure. In addition, much of the applied synthetic fertilizers become lost to the environment through run-off, which contributes to soil degradation. With the increasing demand on agricultural systems to provide food and fibre and the adverse impacts of agricultural production on the soil resource, amendments that support soil …

Diversity And Evolution Of Seeds In Cuscuta (Dodders, Convolvulaceae): Morphology And Structure, Magdalena Olszewski

Theses and Dissertations (Comprehensive)

Cuscuta is a genus of nearly 200 obligate stem parasites with a nearly cosmopolitan distribution and considerable agricultural and ecological significance. Dodder seeds are considered “unspecialized”, with no morphological adaptations towards particular dispersal vectors; however, the seed coat anatomy has recently suggested an adaptation to endozoochory. This is the first attempt to provide a genus-wide overview of the diversity in morphology and anatomy of Cuscuta seeds, together with an assessment of the water gap and exploration of various form-function relationships. I surveyed 104 species belonging to all four Cuscuta subgenera. Seeds of the species of the first infrageneric dodder …

Recoupling Fire And Grazing Reduces Wildland Fuel Loads On Rangelands, Heath D. Starns, Samuel D. Fuhlendore, R. Dwayne Elmore, Dirac L. Twidwell Jr, Eric T. Thacker, Torre J. Hovick, Barney Luttbeg

Department of Agronomy and Horticulture: Faculty Publications

Fire suppression and exclusion, the historically dominant paradigm of fire management, has resulted in major modifications of fire-dependent ecosystems worldwide. These changes are partially credited with a recent increase in wildfire number and extent, as well as more extreme fire behavior. Fire and herbivory historically interacted, and research has shown that the interaction creates a unique mosaic of vegetation heterogeneity that each disturbance alone does not create. Because fire and grazing have largely been decoupled in modern times, the degree to which the interaction affects fuels and fire regimes has not yet been quantified. We evaluated effects of fire-only and …

Where Are All Of Arkansas' Chinquapins? An Ecological Assessment Of Castanea Throughout The State, Logan Pierce Estes

Graduate Theses and Dissertations

Around the turn of the twentieth-century, the chestnut blight fungus (Cryphonectria parasitica) was accidentally introduced into North America. This strong pathogen, which specializes on trees of the genus Castanea, spread rapidly and within half a century had nearly extirpated North America’s Castanea natives from their ranges. During this catastrophe, the American chestnut (Castanea dentata) garnered much of the scientific attention, pushing the other Castanea natives – the chinquapins – to the wayside. More than a century following the spread of the blight, little research into the ecology of North America’s chinquapins had been performed, leaving these trees significantly underrepresented. The …

Understanding Spatial Dynamics Of Tallgrass Prairie Dominated By Tall Fescue, Callie Griffith

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

This study was conducted on restored tallgrass prairie and invaded tallgrass prairie located in the Grand River Grasslands of southern Iowa to determine differences in heterogeneity of plant structure and functional group composition at different scales. Restored tallgrass prairies were seeded with a species-rich seeding mixture and managed by burning the entire prairie, every three years. Data were collected in August 2014 and 2015 to compare heterogeneity of restoration of native plant structure and functional group composition to the heterogeneity of invaded tallgrass prairies that were managed with patch burning and conventionally grazed. Invaded tallgrass prairies were managed with patch-burning …

Grazing Strategy Effects On Utilization, Animal Performance, Aboveground Production, Species Composition, And Soil Properties On Nebraska Sandhills Meadow, Aaron Shropshire

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Ultrahigh stocking density (a.k.a., mob grazing) is proposed as a management tool that results in greater harvest efficiency, animal performance, aboveground plant production, species richness, and soil carbon content. The study objective was to determine grazing treatment, haying, or non-defoliated control effects on forage utilization, aboveground production, animal performance, and soil properties. In 2010, 25 ha of Sandhills meadow were divided into 2 replications of 3 grazing, a hay, and control treatment. Grazing treatments were a 120-pasture rotation with one grazing cycle (mob), a 4-pasture rotation with one cycle (4PR1), and a 4-pasture rotation with two cycles (4PR2) at stocking …

Influence Of Loss Of Function Of The Fatty Acid Desaturase 7 Gene On Photosynthetic Activity And Foliar Redox Status, Janithri Savindya Wickramanayake

Graduate Theses and Dissertations

Fatty Acid Desaturase7 (FAD7) is a chloroplast-localized enzyme that converts 16 and 18 carbon dienoic fatty acids to trienoic fatty acids. The suppressor of prosystemin-mediated response2 (spr2) mutant in tomato (Solanum lycopersicum) and the fad7-1 mutant in Arabidopsis (Arabidopsis thaliana) result in the loss of function of FAD7, which alter the fatty acid profiles of chloroplast membranes and enhance resistance against aphids. This research contributes toward the long-term goal of identifying factors that determine aphid resistance in FAD7 mutants. Previous data suggested constitutive differences between spr2 and WT including increased expression of genes associated with photosynthesis and differences in redox …

Investigation Of Alternative Hosts And Agronomic Factors Affecting Xanthomonas Vasicola Pv. Vasculorum, Causal Agent Of Bacterial Leaf Streak Of Corn, Terra Marie Hartman

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Xanthomonas vasicola pv. vasculorum, causal agent of bacterial leaf streak of corn, was first reported in the U.S. in 2016 on Nebraska corn leaf samples. Prior to this report, the pathogen had only been reported on corn in South Africa. After the Nebraska report, the pathogen was reported on corn in Argentina, Brazil, and several U.S. states. This pathogen has an extensive host range, which includes sugarcane (Saccharum officinarum), grain sorghum (Sorghum bicolor), palm species (Dictyosperma album, Roystonea regia, and Areca catechu) and broom bamboo (Thysanolaena maxima). Plants commonly found in …

Identification Of Genes/Genomic Regions Controlling Resistance To Biotic And Abiotic Stresses In Synthetic Hexaploid Wheat, Madhav Bhatta

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Synthetic hexaploid wheat (SHW; 2n=6x=42, AABBDD, Triticum aestivumL.) is produced from an interspecific cross between durum wheat (2n=4x=28, AABB, T. turgidumL.) and goat grass (2n=2x=14, DD, AegilopstauschiiCoss.). It is reported to have a considerable amount of genetic diversity and is a potential source of novel alleles controlling abiotic and biotic stresses resistance and improving wheat quality. Therefore, the first study was to understand the genetic diversity and population structure of SHWs and compare the genetic diversity of SHWs with elite bread wheat (BW) cultivars. The result of this study identified a wide range of genetic diversity within …

Canavalia Gladiata And Dolichos Lablab Extracts For Sustainable Pest Biocontrol And Plant Nutrition Improvement In El Salvador, Carlos Martinez

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Botanical repellents and pesticides are now being rediscovered as new tools for integrated pest management in order to reduce the use of toxic chemicals in crop production. Canavalia gladiata and Dolichos lablab are two Fabaceae very well adapted to farmlands of El Salvador, effective as living barriers and mostly as cover crops, however, they are not yet very well disseminated. This document describes the potential for using the liquid extracts and the dry flour of raw seeds of those plants for economic benefit and practical convenience for pest management in Salvadorian agriculture under field conditions. Seed extracts were useful when …

Assessment Of Soil Fertility Under Different Land-Use Systems In Dhading District Of Nepal, Sudarshan Kharal, Babu Ram Khanal, Dinesh Panday

Department of Agronomy and Horticulture: Faculty Publications

Unscientific land use and cropping techniques have led high soil erosion and degradation of soil quality in the mid-hills of Nepal. To understand the effects of land use systems for selected soil chemical properties in mid-hills, composite soil samples at 0 cm to 20 cm depth were collected from five different land-use systems: Grassland, forest land, upland, lowland, and vegetable farms from Dhading district of Nepal in 2017. Soil samples were analyzed for soil fertility parameters: Soil pH, organic matter (OM), total nitrogen (N), available phosphorus (P), available potassium (K) and its effect due to different land use systems were …

Research Report: Prevalence And Mechanism Of Atrazine Resistance In Waterhemp From Nebraska, Rodrigo Werle, Mithila Jugulam, Greg Kruger, Amaranatha Vennapusa, Felipe Faleco, Bruno Viera, Spencer Samuelson

Department of Agronomy and Horticulture: Faculty Publications

Waterhemp is a troublesome summer annual broadleaf weed species that has evolved resistance to glyphosate and other herbicide sites of action (SOA) in Nebraska, including to groups 2 (i.e., Classic, Pursuit, FirstRate), 4 (i.e., 2, 4-D), 5(i.e., atrazine) and 27 (e.g., Callisto, Laudis). The overall objectives of this study were to

1. Evaluate the eficay of PRE applied atrazine, metribuzin and sulfentrazone to control Nebraska waterhemp populations;
2. Evaluate the efficacy of POST applied atrazine to control Nebraska waterhemp populations; and
3. Determine the mechanism of atrazine resistance in Nebraska waterhemp populations.

Digital Soil Mapping In The Bara District Of Nepal Using Kriging Tool In Arcgis, Dinesh Panday, Bijesh Maharjan, Devraj Chalise, Ram Kumar Shrestha, Bikesh Twanabasu

Department of Agronomy and Horticulture: Faculty Publications

Digital soil mapping has been widely used to develop statistical models of the relationships between environmental variables and soil attributes. This study aimed at determining and mapping the spatial distribution of the variability in soil chemical properties of the agricultural floodplain lands of the Bara district in Nepal. The study was carried out in 23 Village Development Committees with 12,516 ha total area, in the southern part of the Bara district. A total of 109 surface soil samples (0 to 15 cm depth) were collected and analyzed for pH, organic matter (OM), nitrogen (N), phosphorus (P, expressed as P_{2 …}

Overexpression Of The Sorghum Bicolor Sbccoaomt Alters Cell Wall Associated Hydroxycinnamoyl Groups, Hannah M. Tetreault, Erin D. Scully, Tammy Gries, Nathan A. Palmer, Deanna L. Funnell-Harris, Bruce S. Dien, Gautam Sarath, Thomas E. Clemente, Scott E. Sattler

Department of Agronomy and Horticulture: Faculty Publications

Sorghum (Sorghum bicolor) is a drought tolerant crop, which is being developed as a bioenergy feedstock. The monolignol biosynthesis pathway is a major focus for altering the abundance and composition of lignin. Caffeoyl coenzyme-A O-methyltransferase (CCoAOMT) is an S-adenosyl methionine (SAM)-dependent O-methyltransferase that methylates caffeoyl-CoA to generate feruloyl-CoA, an intermediate required for the biosynthesis of both G- and S-lignin. SbCCoAOMT was overexpressed to assess the impact of increasing the amount of this enzyme on biomass composition. SbCCoAOMT overexpression increased both soluble and cell wall-bound (esterified) ferulic and sinapic acids, however lignin concentration and its composition …

Elucidating Sorghum Biomass, Nitrogen And Chlorophyll Contents With Spectral And Morphological Traits Derived From Unmanned Aircraft System, Jiating Li, Yeyin Shi, Arun-Narenthiran Veeranampalayam-Sivakumar, Daniel P. Schachtman

Department of Agronomy and Horticulture: Faculty Publications

Unmanned aircraft systems (UAS) provide an efficient way to phenotype cropmorphology with spectral traits such as plant height, canopy cover and various vegetation indices (VIs) providing information to elucidate genotypic responses to the environment. In this study, we investigated the potential use of UAS-derived traits to elucidate biomass, nitrogen and chlorophyll content in sorghum under nitrogen stress treatments. A nitrogen stress trial located in Nebraska, USA, contained 24 different sorghum lines, 2 nitrogen treatments and 8 replications, for a total of 384 plots. Morphological and spectral traits including plant height, canopy cover and various VIs were derived from UAS flights …

A Catalog Of Orchid Species And Their Distribution In Mazumbai Forest Reserve, Tanga Region, Tanzania, Sierra Loomis

Independent Study Project (ISP) Collection

Although orchids are common in Mazumbai Forest Reserve (MFR), there are limited resources on where they grow and how to identify them. The primary objective of this study is to create an updated catalog of orchids in MFR, using species abundance, richness and diversity of the orchids as indicators of where orchids prefer to grow in MFR. Orchid species vary greatly as altitude changes, making it important to survey orchids across different altitudes. Therefore, Mazumbai Forest was split into five different altitudinal bands spanning 1400 – 1900m and six 100 x 20m plots in each band were surveyed for both …

The Effect Of Ingredient-Specific Calorie Information On Calories Ordered, Christopher R. Gustafson, Eliana Zeballos

Department of Agronomy and Horticulture: Faculty Publications

Providing calorie labeling is a widely used strategy to combat obesity. However, there is little evidence that the availability of calorie information at food-away-from-home establishments has an effect on food choices. Listing calorie information for each ingredient, though, may allow customers to avoid high-calorie items that add little to their enjoyment. Data from a natural experiment were used to compare total calories ordered before and after the provision of per-ingredient versus for build-your-own sandwiches, and per-sandwich for pre-defined sandwiches, at a supermarket sandwich counter. Sandwich order slips from a Lincoln, Neb. supermarket were collected from December 15, 2016 to February …

Phylogenomic Evidence For Ancient Recombination Between Plastid Genomes Of The Cupressus-Juniperus-Xanthocyparis Complex (Cupressaceae), Andan Zhu, Weishu Fan, Robert P. Adams, Jeffrey P. Mower

Department of Agronomy and Horticulture: Faculty Publications

Background: Phylogenetic relationships among Eastern Hemisphere cypresses, Western Hemisphere cypresses, junipers, and their closest relatives are controversial, and generic delimitations have been in flux for the past decade. To address relationships and attempt to produce a more robust classification, we sequenced 11 new plastid genomes (plastomes) from the five variously described genera in this complex (Callitropsis, Cupressus, Hesperocyparis, Juniperus, and Xanthocyparis) and compared them with additional plastomes from diverse members of Cupressaceae.

Results: Phylogenetic analysis of protein-coding genes recovered a topology in which Juniperus is sister to Cupressus, whereas a tree based on …

Foliar Water Uptake: Processes, Pathways, And Integration Into Plant Water Budgets, Z. Carter Berry, Nathan C. Emery, Sybil G. Gotsch, Gregory R. Goldsmith

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Nearly all plant families, represented across most major biomes, absorb water directly through their leaves. This phenomenon is commonly referred to as foliar water uptake. Recent studies have suggested that foliar water uptake provides a significant water subsidy that can influence both plant water and carbon balance across multiple spatial and temporal scales. Despite this, our mechanistic understanding of when, where, how, and to what end water is absorbed through leaf surfaces remains limited. We first review the evidence for the biophysical conditions necessary for foliar water uptake to occur, focusing on the plant and atmospheric water potentials necessary to …

Mobile Elements Shape Plastome Evolution In Ferns, Tanner A. Robison, Amanda L. Grusz, Paul G. Wolf, Jeffrey P. Mower, Blake D. Fauskee, Karla Sosa, Eric Schuettpelz

Department of Agronomy and Horticulture: Faculty Publications

Plastid genomes display remarkable organizational stability over evolutionary time. From green algae to angiosperms, most plastid genomes are largely collinear, with only a few cases of inversion, gene loss, or, in extremely rare cases, gene addition. These plastome insertions are mostly clade-specific and are typically of nuclear or mitochondrial origin. Here, we expand on these findings and present the first family-level survey of plastome evolution in ferns, revealing a novel suite of dynamic mobile elements. Comparative plastome analyses of the Preridaceae expose several mobile open reading frames that vary in sequence length, insertion site, and configuration among sampled taxa. Even …