Other Plant Sciences Commons^™

Continuous In Situ Soil Nitrate Sensors: The Importance Of High-Resolution Measurements Across Time And A Comparison With Salt Extraction-Based Methods, Yunjiao Zhu, Yuncong Chen, Md. Azahar Ali, Liang Dong, Xinran Wang, Sotirios V. Archontoulis, James Schnable, Michael J. Castellano

Department of Agronomy and Horticulture: Faculty Publications

Soil NO₃^– affects microbial processes, plant productivity, and environmental N losses. However, the ability to measure soil NO₃^– is limited by labor-intensive sampling and laboratory analyses. Hence, temporal variation in soil solution NO₃^– concentration is poorly understood. We evaluated a new potentiometric sensor that continuously measures soil solution NO₃^– concentration with unprecedented specificity due to a novel membrane that serves as a barrier to interfering anions. First, we compared sensor and salt extraction-based measurements of soil NO₃^– in well-controlled laboratory conditions. Second, using 60 d of in situ soil NO …

Soil Response Of Helicopter Liming In The Monongahela National Forest, Jarrett Douglas Fowler

Graduate Theses, Dissertations, and Problem Reports (ETD)

Soils in the Monongahela National Forest (MNF) are acidic due to sandstone parent material, acid deposition, uptake of base cations by vegetation, and release of organic acids by organic matter (OM) decomposition. Increases in soil acidity have caused declines in forest health and changed species composition and nutrient status. Liming can neutralize soil acidity, but no large-scale liming projects have been done on acid forest soils in the USA. In anticipation of acquiring funding for a proposed liming project in the MNF, in 2007 and 2009 10 sites were selected to sample and analyze soils before lime was applied. In …

Abrasive Weeding As A Vehicle For Precision Fertilizer Management In Organic Vegetable Production, Tran Kim Ngan Luong, Frank Forcella, Sharon Clay, Michael S. Douglass, Samuel E. Wortman

Department of Agronomy and Horticulture: Faculty Publications

Abrasive weeding is a nonchemical weed control tactic that uses small, gritty materials propelled with compressed air to destroy weed seedlings. Organic fertilizers have been used successfully as abrasive grits to control weeds, but the goal for this study was to explore the effects of fertilizer grit, application rates, and background soil fertility on weeds, plant available nitrogen (N) uptake, and crop yield. Field trials were conducted in organic ‘Carmen’ sweet red pepper (Capsicum annuum) and organic ‘Gypsy’ broccoli (Brassica oleracea var. italica) and treatments included organic fertilizer grit (8N–0.9P–3.3K vs. 3N–3.1P–3.3K), grit application rates (low …

Development Of Mping-Based Activation Tags For Crop Insertional Mutagenesis, Alexander Johnson, Edward Mcassey, Stephanie Diaz, Jacod Reagin, Priscilla S. Redd, Daymond R. Parrilla, Hanh Nguyen, Adrian Stec, Lauren A.L. Mcdaniel, Thomas E. Clemente, Robert M. Stupar, Wayne A. Parrott, C. Nathan Hancock

Department of Agronomy and Horticulture: Faculty Publications

Modern plant breeding increasingly relies on genomic information to guide crop im- provement. Although some genes are characterized, additional tools are needed to effectively identify and characterize genes associated with crop traits. To address this need, the mPing element from rice was modified to serve as an activation tag to in- duce expression of nearby genes. Embedding promoter sequences in mPing resulted in a decrease in overall transposition rate; however, this effect was negated by using a hyperactive version of mPing called mmPing20. Transgenic soybean events carrying mPing-based activation tags and the appropriate transposase expression cassettes showed evidence of transposition. …

Assessing Short-Term Microalgal Community Responses Over Altering Hydrological Conditions In Experimental Wetlands Of Costal Georgia, Maggie M. Kuhn

College of Graduate Studies: Theses & Dissertations

Wetlands provide valuable ecosystem services such as nutrient cycling and carbon storage. Microalgae (i.e., diatoms) provide the foundation of primary production and determine rates of energy transfer throughout the system. Climate change models predict an increase in frequency of intense storms and severe drought conditions that pose a threat to known hydrological regimes and wetland ecosystem stability. The purpose of my study was to assess the effects of water permanence (i.e., duration of flooding) on diatom community structure in experimental wetlands. I predicted that wetlands with prolonged periods of flooding (i.e., permanent) would harbor a consistent diatom community throughout flooding …

Identification And Utilization Of Genetic Determinants Of Trait Measurement Errors In Image-Based, High-Throughput Phenotyping, Yan Zhou, Aaron Kusmec, Seyed Vahid Mirnezami, Lakshmi Attigala, Srikant Srinivasan, Talukder Zaki Jubery, James Schnable, Maria G. Salas Fernandez, Baskar Ganapathysubramanian, Patrick S. Schnable

Department of Agronomy and Horticulture: Faculty Publications

The accuracy of trait measurements greatly affects the quality of genetic analyses. During automated phenotyping, trait measurement errors, i.e., differences between automatically extracted trait values and ground truth, are often treated as random effects that can be controlled by increasing population sizes and/or replication number. By contrast, there is some evidence that trait measurement errors may be partially under genetic control. Consistent with this hypothesis, we observed substantial non-random, genetic contributions to trait measurement errors for five maize (Zea mays) tassel traits collected using an image-based phenotyping platform. The phenotyping accuracy varied according to whether a tassel exhibited …

Chemical Diversity And Antimicrobial Properties Of Spike-Rush Species And Related Genera (Genus Eleocharis, Family Cyperaceae), Yiru Zhang

Masters Theses

The focus of this research was to explore the chemical diversity and antimicrobial properties of Eleocharis dulcis. By using methanol as a solvent to extract phytochemicals, qualitative comparisons were made between HPLC chromatograms from Eleocharis species and other genera. Meanwhile, this study also examined the antimicrobial properties of phytochemicals extracted from various tissues of Eleocharis dulcis in two different solvents (water or methanol) against two Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) and two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) using a disc diffusion assay. The results suggested that the extracts had limited antimicrobial properties at up to 100 …

The Mechanisms And Consequences Of Shrub Encroachment On The Virginia Barrier Islands, Lauren K. Wood

Theses and Dissertations

Shrub encroachment is a global phenomenon driven by direct and indirect anthropogenic influence which alters plant communities and ecosystem function. Many studies have investigated drivers and consequences of woody plant establishment, but mesic landscapes are underrepresented in the literature. My objective was to assess the mechanisms of Morella cerifera encroachment into coastal mesic grassland, the potential for self-reinforcement, and consequences on community composition, nutrients, and landscape productivity. I studied temperature and water microclimate modification by Morella cerifera presence and removal to understand ecosystem engineering and community composition changes. Additionally, I examined the influence of shrubs on surrounding grassland species traits …

Lichens And Biofilms: Common Collective Growth Imparts Similar Developmental Strategies, Erin C. Carr, Steven D. Harris, Joshua R. Herr, Wayne Riekhof

Department of Plant Pathology: Faculty Publications

Lichens are traditionally defined as a symbiotic relationship between fungi and algae and/or cyanobacteria. This union forms a unique structure called the thallus, which attaches to surfaces such as rocks and tree bark. Recent reports challenge the view that lichens are comprised of one fungus and one photobiont, and instead suggest that they are a consortium of microbes. Much of lichen biology remains unknown as most of our knowledge of lichens is limited to morphological characteristics with little to no functional analysis of lichen genes. However, lichens and biofilms share many similar physiological traits which when compared may assist in …

Root And Crown Rot Pathogens Found On Dry Beans Grown In Mozambique, Suzana Vanessa Ismael Fernandes, G. Godoy-Lutz, Celestina Nhagupana Jochua, Carlos A. Urrea, Kent M. Eskridge, James R, Steadman, Joshua Herr

Department of Plant Pathology: Faculty Publications

Dry edible beans are a vital food source in Mozambique, East Africa—one that alleviates hunger and malnutrition and adds value to the economy. In recent years, root/crown rot (RCR) pathogens have emerged as limiting constraints in dry bean production. Not much has been characterized concerning the causal agents of RCR in Mozambique. The purpose of this study was to identify the primary pathogen(s) associated with RCR dry bean samples collected at breeder nursery sites and farmer fields in Mozambique using molecular sequencing and culture-based methods. Sequencing revealed, not surprisingly, an increased diversity of fungal/oomycete operational taxonomic units when compared to …

Household Smoke-Exposure Risks Associated With Cooking Fuels And Cooking Places In Tanzania: A Cross-Sectional Analysis Of Demographic And Health Survey Data, Mazbahul G. Ahamad, Fahian Tanin, Nawaraji Shrestha

Department of Agronomy and Horticulture: Faculty Publications

Household smoke-exposure risk (SER) can be defined through the assessment of cooking fuels (smoke and no smoke-producing) and cooking places (indoor and outdoor) related information, which represent different levels of household air pollution. This study aimed to explore the prevalence and geographical variations in smoke-exposure risks (SERs) associated with indoor and outdoor cooking practices and use of smoke-producing and non-smoke-producing cooking fuels in Tanzania. We further investigated the social and spatial features associated with household SERs. We defined an indicator variable, the household SER, using country-level, cross-sectional data on cooking fuels and cooking places obtained from the 2015–2016 Tanzania Demographic …

Officially Confirmed Covid-19 And Unreported Covid-19–Like Illness Death Counts: An Assessment Of Reporting Discrepancy In Bangladesh, Mazbahul G. Ahamad, Fahian Tanin, Byomkesh Talukder, Monir Ahmed

Department of Agronomy and Horticulture: Faculty Publications

Reporting discrepancies between officially confirmed COVID-19 death counts and unreported COVID- 19–like illness (CLI) death counts have been evident across the world, including Bangladesh. Publicly available data were used to explore the differences between confirmed COVID-19 death counts and deaths with possible COVID-19 symptoms between March 2, 2020 and August 22, 2020. Unreported CLI death counts totaled more than half of the confirmed COVID-19 death counts during the study period. However, the reporting authority did not consider CLI deaths, which might produce incomplete and unreliable COVID-19 data and respective mortality rates. All deaths with possible COVID-19 symptoms need to be …

Nitrogen Response Functions Targeted To Technology Extrapolation Domains In Ethiopia Using Ceres-Maize, Feyera Merga Liben, Charles S. Wortmann, Haishun Yang, Tsegaue Tadesse, Z. P. Stewart, D. Wegary, W. Mupangwa

Department of Agronomy and Horticulture: Faculty Publications

The profitability of fertilizer-N use can be optimized using N response functions specific to climate-based technology extrapolation domains (TED). Crop growth simulation can complement field research for targeting of response functions. The objective of this study was to target maize (Zea mays L.) N response functions to seven TED in Ethiopia through CERES-Maize simulation of continuous maize over 30 yr. The complete factorial set of treatments included seven levels of N in 25 kg ha⁻¹ increments under no-till (NT) and conventional tillage (CT) systems. The CERES-Maize simulated experiments were done for two or three sites per TED. Nitrogen …

Wild Emmer Introgression Alters Root-To-Shoot Growth Dynamics In Durum Wheat In Response To Water Stress, Harel Bacher, Feiyu Zhu, Tian Gao, Kan Liu, Balpreet Dhatt, Tala Awada, Chi Zhang, Assaf Distelfeld, Hongfeng Yu, Zvi Peleg, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Water deficit during the early vegetative growth stages of wheat (Triticum) can limit shoot growth and ultimately impact grain productivity. Introducing diversity in wheat cultivars to enhance the range of phenotypic responses to water limitations during vegetative growth can provide potential avenues for mitigating subsequent yield losses. We tested this hypothesis in an elite durum wheat background by introducing a series of introgressions from a wild emmer (Triticum turgidum ssp. dicoccoides) wheat. Wild emmer populations harbor rich phenotypic diversity for drought-adaptive traits. To determine the effect of these introgressions on vegetative growth under water-limited conditions, we used image-based phenotyping to …

Loss Of Comt Activity Reduces Lateral Root Formation And Alters The Response To Water Limitation In Sorghum Brown Midrib (Bmr) 12 Mutant, Manny Saluja, Feiyu Zhu, Hongfeng Yu, Harkamal Walia, Scott E. Sattler

Department of Agronomy and Horticulture: Faculty Publications

Lignin is a key target for modifying lignocellulosic biomass for efficient biofuel production. Brown midrib 12 (bmr12) encodes the sorghum caffeic acid O-methyltransferase (COMT) and is one of the key enzymes in monolignol biosynthesis. Loss of function mutations in COMT reduces syringyl (S) lignin subunits and improves biofuel conversion rate. Although lignin plays an important role in maintaining cell wall integrity of xylem vessels, physiological and molecular consequences due to loss of COMT on root growth and adaptation to water deficit remain unexplored.

We addressed this gap by evaluating the root morphology, anatomy and transcriptome of bmr12 mutant. The mutant …

Does Biochar Improve All Soil Ecosystem Services?, Humberto Blanco-Canqui

Department of Agronomy and Horticulture: Faculty Publications

Biochar is considered to sequester C and deliver other soil ecosystem services, but an overview that synthesizes the current knowledge of biochar implications on all essential soil ecosystem services is difficult to find in the ample biochar literature. Most previous research and review articles on this topic focused on a single ecosystem service and did not integrate all essential soil ecosystem services. This overview paper (1) synthesizes the impacts of biochar on water and wind erosion, C sequestration, soil water, nutrient leaching, soil fertility, crop yields, and other soil ecosystem services based on published literature and (2) highlights remaining research …

Intervention Of Climate-Smart Practices In Wheat Under Rice-Wheat Cropping System In Nepal, Janma Jaya Gairhe, Mandeep Adhikari, Deepak Ghimire, Arun Khatri-Chhetri, Dinesh Panday

Department of Agronomy and Horticulture: Faculty Publications

Besides a proper agronomic management followed by Nepalese farmers, wheat (Triticum aestivum L.) production has been severely affected by changing climate. There are many interventions, including climate-smart practices, to cope with this situation and possibly enhance crop and soil productivity. Field experiments were set up in a randomized complete block design with six treatments (TRT) with four replications in three locations (LOC) during wheat-growing seasons in Nepal from 2014 to 2016. Treatments included (i) Controlled Practice (CP), (ii) Improved Low (IL), (iii) Improved High (IH), (iv) Climate Smart Agriculture Low (CSAL), (v) Climate Smart Agriculture Medium (CSAM), and (vi) …

Effect Of Foliar Micronutrients (B, Mn, Fe, Zn) On Maize Grain Yield, Micronutrient Recovery, Uptake, And Partitioning, Zachary P. Stewart, Ellen T. Paparozzi, Charles S. Wortmann, Prakash Kumar Jha, Charles A. Shapiro

Department of Agronomy and Horticulture: Faculty Publications

Timing of micronutrient demand and acquisition by maize (Zea Mays L.) is nutrient spe‐ cific and associated with key vegetative and reproductive growth stages. The objective of this study was to determine the fate of foliar‐applied B, Fe, Mn, Zn, and Fe/Zn together, evaluate the effect of foliar micronutrients applied at multiple rates and growth stages on maize grain yield, and deter‐ mine their apparent nutrient recovery efficiency (ANR). Five Randomized Complete Block Design (RCBD) experiments were conducted in 2014 and 2015 at five locations across Nebraska. Total dry matter was collected at 5–6 stages, and separated into leaves, stalk, …

Genomic Resources In Plant Breeding For Sustainable Agriculture, Mahendar Thudi, Rajeev K. Varshney, James C. Schnable

Department of Agronomy and Horticulture: Faculty Publications

Climate change during the last 40 years has had a serious impact on agriculture and threatens global food and nutritional security. From over half a million plant species, cereals and legumes are the most important for food and nutritional security. Although systematic plant breeding has a relatively short history, con- ventional breeding coupled with advances in technology and crop management strategies has increased crop yields by 56 % globally between 1965− 85, referred to as the Green Revolution. Nevertheless, increased demand for food, feed, fiber, and fuel necessitates the need to break existing yield barriers in many crop plants. In …

Responses Of Soil Surface Greenhouse Gas Emissions To Nitrogen And Sulfur Fertilizer Rates To Brassica Carinata Grown As A Bio-Jet Fuel, Dwarika Bhattarai, Gandura O. Abagandura, Thandiwe Nleya, Sandeep Kumar

Department of Agronomy and Horticulture: Faculty Publications

Carinata (Brassica carinata A. Braun), a non-food oilseed crop and an alternative bio-jet fuel feedstock, has received attention for its potential as a low-input option for production in the semi-arid region of the Northern Great Plains of the United States. Research addressing the impacts of nitrogen (N) and sulfur (S) fertilizers on soils and greenhouse gas (GHG; CO2, N2O, and CH4) emissions from carinata production are limited. Thus, objective of this study was to evaluate the impact of different rates of N and S fertilizers applied to carinata on soil properties and GHG emissions. Field experiments were conducted in 2017 …