Agricultural Science Commons^™

The Balancing Act Of Cytokinin In Environmental Stress Tolerance, Sumudu Sandeepani Karunadasa

Theses and Dissertations--Plant and Soil Sciences

Cytokinin, long known as a phytohormone that regulates plant growth and development, has been recently recognized as an important regulator of stress responses. However, our current knowledge about the mechanisms by which cytokinin regulates stress responses is fragmentary, as many of the studies in this field yielded conflicting results. Most of the work described here has focused on analyses of the molecular mechanisms of cytokinin-dependent regulation of growth and development under stress conditions, with an emphasis on the role of cytokinin-dependent regulation of protein synthesis in development and stress tolerance.

One of the important contributions of this study is the …

Effect Of Organic Soil Amendment On Hemp, Mounica Talasila

Murray State Theses and Dissertations

The research study is about the impact of different levels of organic soil amendment on the levels of psychoactive compounds produced in industrial hemp. Inorganic or chemical pesticides or fertilizers are not as extensively used in hemp as in other crops. Apart from this, using an organic soil amendment would be an environmentally sustainable way. A randomized block design (RBD) model was used to study the impacts of the soil amendment. The soil amendment used is called “Rehab” a product of Organilock created from the remnants of animals like fish and chicken. This research design has 3 different soil amendment …

Toward A Holistic Agricultural Student Recruitment Model: A National Analysis Of The Factors Affecting Students’ Decision To Pursue An Agricultural Related Degree, Antoine J. Alston, Richie Roberts, Chastity W. English

Journal of Research in Technical Careers

Currently, the agricultural industry struggles to fill positions with qualified agricultural workers. Therefore, it is critical to attract high caliber individuals to agricultural degree programs that are prepared to enter the workforce with the skills needed to navigate complex issues and problems. The purpose of this national study was to identify key factors that influence the recruitment of agriculture students at land-grant and non-land-grant universities. Using Chapman’s model of student success as our conceptual lens, we tested 66 factors identified in the literature as successful recruitment strategies for colleges of agriculture based on students’ personal characteristics as well as key …

Occurrence Of Plant-Parasitic Nematodes On Enset (Ensete Ventricosum) In Ethiopia With Focus On Pratylenchus Goodeyi As A Key Species Of The Crop, Selamawit A. Kidane, Beira H. Meressa, Solveig Haukeland, Trine Hvoslef-Eide, Christer Magnusson, Marjolein Couvreur, Wim Bert, Danny L. Coyne

All Peer-Reviewed Publications

Summary - Enset (Ensete ventricosum) is an important starch staple crop, cultivated primarily in south and southwestern Ethiopia. Enset is the main crop of a sustainable indigenous African system that ensures food security in a country that is food deficient. Related to the banana family, enset is similarly affected by plant-parasitic nematodes. Plant-parasitic nematodes impose a huge constraint on agriculture. The distribution, population density and incidence of plant-parasitic nematodes of enset was determined during August 2018. A total of 308 fields were sampled from major enset-growing zones of Ethiopia. Eleven plant-parasitic nematode taxa were identified, with Pratylenchus (lesion nematode) being …

Unlocking Maize Crop Productivity Through Improved Management Practices In Northern Tanzania, Kihara J, Kizito F, Jumbo M, Kinyua M, M. Bekunda

All Peer-Reviewed Publications

Addressing the problem of low crop productivity and food insecurity can be accelerated through community-centered implementation of good agricultural management practices. This study was conducted in Babati, Northern Tanzania. The objective of the study was to determine nitrogen (N) and phosphorus (P) application requirements for maize, and demonstrate economically viable best bet yield-improving management technologies under three ecozones namely; ‘low elevation low rainfall', ‘medium elevation high rainfall' and ‘medium elevation low rainfall' ecozone. Two sets of trials were conducted: N (0, 45, 90, 120 and 150 kg ha-1) and P (0, 15, 30, 40 kg ha-1) response trials in 16 …

Impact Of Integrated Fruit Fly Management Strategy On Food Security Among Smallholder Mango Farmers In Kenya, P. N. Nyang'au, B. W. Muriithi, J. M. Nzuma, P. Irungu, H. M. Gichungi, G. Diiro

All Peer-Reviewed Publications

Adoption of agricultural innovations is perceived as a key avenue for poverty reduction and improved food and nutritional security in developing countries. The International Centre for Insect Physiology and Ecology (icipe) has developed and implemented a set of Integrated Pest Management (IPM) strategies in several sub-Saharan African countries aimed at controlling mango infesting fruit flies (Bactrocera dorsalis). Although positive returns from the use of fruit fly IPM have already been documented, the impact of these technologies on food security is not well understood. This study evaluated the impact of the IPM strategy on food security with the help of a …

Comparing Water Quality For Aquaponics Systems With Different Solids Removal Methods And Biofilter Media, And Effluent Output To Grow Beds, John W. Cutt, Heather M. Joesting, Brigette A. Brinton

Honors College Theses

Aquaponics is a closed-loop, sustainable method of food production that combines fish and plant production. This method of agriculture has the potential to bring fresh, local food to food-insecure areas, but challenges remain due to high operating costs. In order to develop a strong aquaponics industry, the creation of the most efficient system designs will be critical in optimizing production. This study’s purpose was to compare water quality between two aquaponics system designs that differ in filtration and solid removal methods. System 1 used a sock filter for solid removal and Kaldnes media for biofiltration while System 2 used a …

Application Of Advanced Algorithms And Statistical Techniques For Weed-Plant Discrimination, Saman Akbar Zadeh

Theses: Doctorates and Masters

Precision agriculture requires automated systems for weed detection as weeds compete with the crop for water, nutrients, and light. The purpose of this study is to investigate the use of machine learning methods to classify weeds/crops in agriculture. Statistical methods, support vector machines, convolutional neural networks (CNNs) are introduced, investigated and optimized as classifiers to provide high accuracy at high vehicular speed for weed detection.

Initially, Support Vector Machine (SVM) algorithms are developed for weed-crop discrimination and their accuracies are compared with a conventional data-aggregation method based on the evaluation of discrete Normalised Difference Vegetation Indices (NDVIs) at two different …

Local Binary Pattern Based Algorithms For The Discrimination And Detection Of Crops And Weeds With Similar Morphologies, Vi Nguyen Thanh Le

Theses: Doctorates and Masters

In cultivated agricultural fields, weeds are unwanted species that compete with the crop plants for nutrients, water, sunlight and soil, thus constraining their growth. Applying new real-time weed detection and spraying technologies to agriculture would enhance current farming practices, leading to higher crop yields and lower production costs. Various weed detection methods have been developed for Site-Specific Weed Management (SSWM) aimed at maximising the crop yield through efficient control of weeds. Blanket application of herbicide chemicals is currently the most popular weed eradication practice in weed management and weed invasion. However, the excessive use of herbicides has a detrimental impact …

Seed Quality And Mycoflora Associated With Chickpea (Cicer Arientinum L.) Seed In Ethiopia, G. Getaneh, T. Tefera, F. Lemmessa, S. Ahmed, A. Zewudie

All Peer-Reviewed Publications

The study was conducted at Ethiopian Institute of Agricultural Research, Haramaya University and Jimma University, Ethiopia. Crop yield is directly associated with the physical and biological quality of planting material or seed. Ninety-nine (99) chickpea seed lot samples were collected for physical purity, seed health and germination tests from major chickpea growing areas in Ethiopia in the 2016/17 cropping season to assess the status of chickpea seed health and quality among subsistence farmers, research stations and seed growers. The seed lots were grouped as researcher saved, farmers saved and seed growers’ saved seed. The maximum physical purity of 97.5% was …

Diversity Of Fall Armyworm, Spodoptera Frugiperda And Their Gut Bacterial Community In Kenya, Joseph Gichuhi, Subramanian Sevgan, Fathiya Khamis, Johnnie Van Den Berg, Hannalene Du Plessis, Sunday Ekesi, Jeremy K. Herren

All Peer-Reviewed Publications

Background: The invasive fall armyworm, Spodoptera frugiperda (J.E. Smith) is a polyphagous pest that causes widespread damage particularly to maize and sorghum in Africa. The microbiome associated with S. frugiperda could play a role in the insects' success and adaptability. However, bacterial communities in S. frugiperda remain poorly studied. Methods: We investigated the composition, abundance and diversity of microbiomes associated with larval and adult specimens of S. frugiperda collected from four maize growing regions in Kenya through high throughput sequencing of the bacterial 16S rRNA gene. The population structure of S. frugiperda in Kenya was assessed through amplification of the …

A Justification For Continued Management Of Turfgrass During Economic Contraction, James T. Brosnan, Ambika Chandra, Roch E. Gaussoin, Alec Kowalewski, Bernd Leinauer, Frank S. Rossi, Douglas J. Soldat, John C. Stier, J. Bryan Unruh

Department of Agronomy and Horticulture: Faculty Publications

A novel coronavirus, termed COVID-19, spread worldwide and become a global pandemic in 2020. Forecasts show that COVID-19 will cause substantial economic contraction affecting almost every industry. Managed turfgrass, particularly in urban settings, has many positive societal and environmental benefits. In a contracted economy, will resources be available to manage turfgrass to achieve these benefits? In this paper, we outline the benefits of managed turfgrass on golf courses, playing fields, recreational parks, and urban landscapes to assist decision makers with resource allocation in the COVID-19 era.

Soil Sample Timing, Nitrogen Fertilization, And Incubation Length Influence Anaerobic Potentially Mineralizable Nitrogen, Jason Clark, Kristen S. Veum, Fabián G. Fernández, Newell R. Kitchen, James J. Camberato, Paul Carter, Richard Ferguson, David W. Franzen, Daniel E. Kaiser, Carrie A. M. Laboski, Emerson Nafziger, Carl J. Rosen, John E. Sawyer, John F. Shanahan

Department of Agronomy and Horticulture: Faculty Publications

Understanding the variables that affect the anaerobic potentially mineralizable N (PMNan) test should lead to a standard procedure of sample collection and incubation length, improving PMNan as a tool in corn (Zea mays L.) N management. We evaluated the effect of soil sample timing (preplant and V5 corn development stage [V5]), N fertilization (0 and 180 kg ha−1) and incubation length (7, 14, and 28 d) on PMNan (0–30 cm) across a range of soil properties and weather conditions. Soil sample timing, N fertilization, and incubation length affected PMNan differently based on soil and weather conditions. Preplant vs. V5 PMNan …

Cover Crops And Weed Suppression In The U.S. Midwest: A Meta-Analysis And Modeling Study, Virginia Nicholas, Rafael Martinez-Feria, David Weisberger, Sarah Carlson, B. Basso, Andrea Basche

Department of Agronomy and Horticulture: Faculty Publications

In addition to soil health and conservation benefits, cover crops (CCs) may offer weed control in the midwestern United States, but individual studies report vary- ing effects. We conducted a meta-analysis of studies measuring weed biomass (WBIO) or density (WDEN) in paired CC and no-cover treatments in corn (Zea mays L.)–soybean [Glycine max (L.) Merr] rotations in the U.S. Midwest. Fifteen studies provided 123 paired comparisons of WBIO and 119 of WDEN. Only grass CCs significantly reduced WBIO, while no CC reduced WDEN. We found no evidence CC management factors (e.g., termination method) directly affected out- comes. Our dataset showed …

Quantifying On‐Farm Nitrous Oxide Emission Reductions In Food Supply Chains, A.J. Eagle, E. Mclellan, E.M. Brawner, M.H. Chantigny, Eric A. Davidson, J.B. Dickey, Bruce A. Linquist, T.M. Maaz, D.E. Pelster, Cameron M. Pittelkow, C. Van Kessel, T.J. Vyn, K. G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

Reducing nitrous oxide (N2O) emissions from agriculture is critical to limiting future global warming. In response, a growing number of food retailers and manufacturers have committed to reducing N2O emissions from their vast networks of farmer suppliers by providing technical assistance and financial incentives. A key challenge for such companies is demonstrating that their efforts are leading to meaningful progress toward their climate mitigation commitments. We show that a simplified version of soil surface nitrogen (N) balance—or partial N balance—the difference between N inputs to and outputs

from a farm field (fertilizer N minus crop N), is a robust indicator …

Woody Plant Encroachment And The Sustainability Of Priority Conservation Areas, Dillon Fogarty, Caleb P. Roberts, Daniel R. Uden, Victoria M. Donovan, Craig R. Allen, David E. Naugle, Matthew O. Jones, Brady W. Allred, Dirac L. Twidwell Jr

Department of Agronomy and Horticulture: Faculty Publications

Woody encroachment is a global driver of grassland loss and management to counteract encroachment represents one of the most expensive conservation practices implemented in grasslands. Yet, outcomes of these practices are often unknown at large scales and this constrains practitioner’s ability to advance conservation. Here, we use new monitoring data to evaluate outcomes of grassland conservation on woody encroachment for Nebraska’s State Wildlife Action Plan, a statewide effort that targets management in Biologically Unique Landscapes (BULs) to conserve the state’s natural communities. We tracked woody cover trajectories for BULs and compared BUL trajectories with those in non-priority landscapes (non-BULs) to …

Strategic Switchgrass (Panicum Virgatum) Production Within Row Cropping Systems: Regional-Scale Assessment Of Soil Erosion Loss And Water Runoff Impacts, Enheng Wang, R. M. Cruse, Bharat Sharma-Acharya, Daryl E. Herzmann, Brian K. Gelder, David E. James, Dennis C. Flanagan, Humberto Blanco-Canqui, Robert B. Mitchell, David Laird

Department of Agronomy and Horticulture: Faculty Publications

A strong need exists for tools to assess the efficacy of conservation practices across large regions supporting informed policy decisions that may lead to better soil and water conservation while optimizing agricultural production options. Perennial warm-season grasses (WSGs) such as switchgrass (Panicum virgatum), can be grown on marginally productive and/or environmentally sensitive lands to meet growing bioenergy demands while reducing water runoff and soil erosion compared to current row crop systems. Quantifying the soil and water conservation effects of WSG when strategically placed on the landscape would help support decisions favoring both economic and environmental benefits. We used the Daily …

Soil Aggregation As Affected By Application Of Diverse Organic Materials, Maman Garba, Charles S. Wortmann, Humberto Blanco-Canqui

Department of Agronomy and Horticulture: Faculty Publications

Application of organic materials can amend soil for improved water infiltration and reduced erodibility with effects varying with soil properties and the organic amendment type and rate. The effects of four livestock manures, three municipal biosolids, and one industrial by-product on dry and wet soil aggregate stability were evaluated at six sites in Nebraska. The amendments had similar C/N ratios but the biosolids had relatively high concentrations of lignin and cellulose. Soil organic matter (SOM) ranged from 21 to 65 g kg−1 and soils were silty clay loam, silt loam, or loamy sand. Soil was sampled for the 0- to …

Benchmarking The Agronomic Performance Of Biodegradable Mulches Against Polyethylene Mulch Film: A Meta‐Analysis, Mauro B.D. Tofanelli, Samuel E. Wortman

Department of Agronomy and Horticulture: Faculty Publications

Growers are interested in biodegradable alternatives to petroleum‐based polyethylene mulch film (PEM). However, many growers cite limited knowledge about biodegradable mulch films (BDMs) as a significant barrier to adoption. Agronomic field tests of BDMs are often limited temporally or spatially, and the variability of performance results relative to PEM may be contributing to this perceived knowledge gap. Our objective was to use data available in the scientific literature to provide the first quantitative performance benchmark of BDMs against PEM. We extracted data from 66 articles for meta‐analysis. Response ratios were calculated for comparison of BDMs relative to black PEM, and …

Transformative Education In Agroecology: Student, Teacher, And Client Involvement In Co-Learning, Charles A. Francis, Anna Marie Nicolaysen, Geir Lieblein, Tor Arvid Breland

Department of Agronomy and Horticulture: Faculty Publications

Educational methods have evolved rapidly in agroecology, which is a complex and holistic field without a long history or the formal tradition of any single academic discipline. Definitions of agroecology have evolved from its initial conception as a marriage of agriculture with ecology, to an aggregation of different paths including science, practices, and movements, and recently as a broad appreciation of the ecology of food systems. In contrast with traditional courses that begin with a history of the discipline and review the contributions of early leaders, we have embraced phenomenology to firmly establish roots in students’ learning through their experiences …

Wheat Growth Monitoring And Yield Estimation Based On Multi-Rotor Unmanned Aerial Vehicle, Zhaopeng Fu, Jie Jang, Yang Gao, Brian Krienke, Meng Wang, Kaitai Zhong, Qiang Cao, Yongchao Tian, Yan Zhu, Weixing Cao, Xiaojun Liu

Department of Agronomy and Horticulture: Faculty Publications

Leaf area index (LAI) and leaf dry matter (LDM) are important indices of crop growth. Real-time, nondestructive monitoring of crop growth is instructive for the diagnosis of crop growth and prediction of grain yield. Unmanned aerial vehicle (UAV)-based remote sensing is widely used in precision agriculture due to its unique advantages in flexibility and resolution. This study was carried out on wheat trials treated with different nitrogen levels and seeding densities in three regions of Jiangsu Province in 2018–2019. Canopy spectral images were collected by the UAV equipped with a multi-spectral camera during key wheat growth stages. To verify the …

Gwas: Fast-Forwarding Gene Identification And Characterization In Temperate Cereals: Lessons From Barley – A Review, Ahmad M. Alqudah, Ahmed Sallam, P. Stephen Baenziger, Andreas Börner

Department of Agronomy and Horticulture: Faculty Publications

Understanding the genetic complexity of traits is an important objective of small grain temperate cereals yield and adaptation improvements. Bi-parental quantitative trait loci (QTL) linkage mapping is a pow- erful method to identify genetic regions that co-segregate in the trait of interest within the research pop- ulation. However, recently, association or linkage disequilibrium (LD) mapping using a genome-wide association study (GWAS) became an approach for unraveling the molecular genetic basis underlying the natural phenotypic variation. Many causative allele(s)/loci have been identified using the power of this approach which had not been detected in QTL mapping populations. In barley (Hordeum …

The State Of Sustainable Agriculture And Agroecology Research And Impacts: A Survey Of U.S. Scientists, Marcia Delonge, Tali Robbins, Andrea D. Basche, Lindsey Haynes-Maslow

Department of Agronomy and Horticulture: Faculty Publications

A growing body of research suggests that although sustainable agriculture, particularly agroecology, can address challenges such as those related to climate change, ecosystem services, food insecurity, and farmer livelihoods, the transition to such systems remains limited. To gain insight into the state of U.S. sustainable agriculture and agroecology, we developed a 28-question mixed-method survey that was administered to scientists in these fields. Respondents (N=168) represented diverse locations, institutions, and career stages. They offered varied definitions of sustainable agriculture, with 40% considering economic and social well-being to be core components. Respondents identified the amount and duration of public research …

Dicamba Retention In Commercial Sprayers Following Triple Rinse Cleanout Procedures, And Soybean Response To Contamination Concentrations, Frances B. Browne, Xiao Li, Katilyn J. Price, Jianping Wang, Yi Wang, Greg R. Kruger, Jeff Golus, Gabrielle De Castro Macedo, Bruno C. Vieira, Tyler Sandlin

Department of Agronomy and Horticulture: Faculty Publications

The commercial launch of dicamba‐tolerant (DT) crops has resulted in increased dicamba usage and a high number of dicamba off‐target movement complaints on sensitive soybeans (Glycine max L.). Dicamba is a synthetic auxin and low dosages as 0.028 g ae ha−1 can induce injury on sensitive soybean. Tank contamination has been identified as one of the sources for unintended sensitive crop exposure. The labels of new dicamba formulations require a triple rinse cleanout procedure following applications. Cleanout efficacy might vary based on the sprayer type and procedure followed. This study was performed to quantify dicamba retention in commercial sprayers and …

Prediction Strategies For Leveraging Information Of Associated Traits Under Single- And Multi-Trait Approaches In Soybeans, Reyna Persa, Arthur Bernardeli, Diego Jarquin

Department of Agronomy and Horticulture: Faculty Publications

The availability of molecular markers has revolutionized conventional ways to improve genotypes in plant and animal breeding through genome-based predictions. Several models and methods have been developed to leverage the genomic information in the prediction context to allow more efficient ways to screen and select superior genotypes. In plant breeding, usually, grain yield (yield) is the main trait to drive the selection of superior genotypes; however, in many cases, the information of associated traits is also routinely collected and it can potentially be used to enhance the selection. In this research, we considered different prediction strategies to leverage the information …

Rhizosphere Microbiome Of Arid Land Medicinal Plants And Extra Cellular Enzymes Contribute To Their Abundance, Abdul Latif Khan, Sajjad Asaf, Raeid M. M. Abed, Yen Ning Chai, Ahmed N. Al-Rawahi, Tupan Kumar Mohanta, Ahmed Al-Rawahi, Daniel P. Schachtman, Ahmed Al-Harrasi

Department of Agronomy and Horticulture: Faculty Publications

Revealing the unexplored rhizosphere microbiome of plants in arid environments can help in understanding their interactions between microbial communities and plants during harsh growth conditions. Here, we report the first investigation of rhizospheric fungal and bacterial communities of Adenium obesum, Aloe dhufarensis and Cleome austroarabica using next-generation sequencing approaches. A. obesum and A. dhufarensis grows in dry tropical and C. austroarabica in arid conditions of Arabian Peninsula. The results indicated the presence of 121 fungal and 3662 bacterial operational taxonomic units (OTUs) whilst microbial diversity was significantly high in the rhizosphere of A. obesum and A. dhufarensis and low …

Benchmarking Impact Of Nitrogen Inputs On Grain Yield And Environmental Performance Of Producer Fields In The Western Us Corn Belt, Fatima A.M. Tenorio, Eileen L. Mclellan, Alison J. Eagle, Kenneth G. Cassman, Daryl Andersen, Marie Krausnick, Russell Oaklund, John Thorburn, Patricio Grassini

Department of Agronomy and Horticulture: Faculty Publications

Benchmarking crop yields against nitrogen (N) input levels can help provide opportunities to improve N ferti-lizer efficiency and reduce N losses on maize in the US Corn Belt by identifying fields most likely to benefit from improved N management practices. Here, we evaluated a large producer database that includes field-level data on yield and applied N inputs from 9280 irrigated and rainfed fields over a 7-year period (2009–2015) in Nebraska (USA). A spatial framework, based on technology extrapolation domains, was used to cluster each field into spatial units with similar climate and soil type that represent 1.3 million ha of …

Leveraging Genome-Enabled Growth Models To Study Shoot Growth Responses To Water Deficit In Rice, Malachy T. Campbell, Alexandre Grondin, Harkamal Walia, Gota Morota

Department of Agronomy and Horticulture: Faculty Publications

lucidating genotype-by-environment interactions and partitioning its contribution to phenotypic variation remains a challenge for plant scientists. We propose a framework that utilizes genome-wide markers to model genotype-specific shoot growth trajectories as a function of time and soil water availability. A rice diversity panel was phenotyped daily for 21 d using an automated, high-throughput image-based, phenotyping platform that enabled estimation of daily shoot biomass and soil water content. Using these data, we modeled shoot growth as a function of time and soil water content, and were able to determine the time point where an inflection in the growth trajectory occurred. We …

Training Future Agriculture Professionals In Landowner–Tenant Conservation Decision-Making, Andrea Basche, Angie Carter

Department of Agronomy and Horticulture: Faculty Publications

The landowner–tenant relationship is important to the implementation of conser- vation on agricultural lands. Women own or co-own a significant portion of U.S. farmland yet are underrepresented in conservation research. The next generation of agriculture professionals can benefit from first-hand experience in assisting women landowners and their tenants in navigating the complexities of conser- vation decision-making. This article analyzes undergraduate student perceptions of landowner–tenant relationships in conservation management through their engagement in case studies with women landowner–tenant pairs in the Western Corn Belt. Student groups were asked to complete a management improvement plan that both incorporated the agronomic and conservation …

Is Allelopathy From Winter Cover Crops Affecting Row Crops?, Katja Koehler-Cole, Sydney Everhart, Yan Gu, Christopher A. Proctor, Margarita Marroquin-Guzman, Daren Redfearn, Roger W. Elmore

Department of Agronomy and Horticulture: Faculty Publications

Cover crops (CC) have been explored in corn (Zea mays L.), cotton (Gossypium hirsutum L.), soybean [Glycine max (L.) Merr.], and wheat (Triticum aestivum L.) systems for their allelopathic potential to control weeds. However, allelopathic compounds may negatively affect these row crops by reducing germination, emergence, and grain yields. We reviewed studies that document allelopathic effects of CC on subsequent row crops in field and laboratory settings. We summarize the influence of CC management, including biomass production, planting and termination timing on allelochemical quantity. Our review found few studies documenting allelopathic effects of CC on row …