Plant Biology Commons^™

Genetic Architecture Of Soybean Yield And Agronomic Traits, Brian W. Diers, Jim Specht, Katy Martin Rainey, Perry Cregan, Qijian Song, Vishnu Ramasubramanian, George Graef, Randall L. Nelson, William Schapaugh, Dechun Wang, Grover Shannon, Leah Mchale, Stella K. Kantartzi, Alencar Xavier, Rouf Mian, Robert M. Stupar, Jean-Michel Michno, Yong-Qiang Charles An, Wolfgang Goettel, Russell Ward, Carolyn Fox, Alexander E. Lipka, David Hyten, Troy Cary, William D. Beavis

Department of Agronomy and Horticulture: Faculty Publications

Soybean is the world’s leading source of vegetable protein and demand for its seed continues to grow. Breeders have successfully increased soybean yield, but the genetic architecture of yield and key agronomic traits is poorly understood. We developed a 40-mating soybean nested association mapping (NAM) population of 5,600 inbred lines that were characterized by single nucleotide polymorphism (SNP) markers and six agronomic traits in field trials in 22 environments. Analysis of the yield, agronomic, and SNP data revealed 23 significant marker-trait associations for yield, 19 for maturity, 15 for plant height, 17 for plant lodging, and 29 for seed mass. …

Influence Of Harvest Date On Seed Yield And Quality In Forage Kochia, Cody F. Creech, Blair L. Waldron, Corey V. Ransom, Dale R. Zobell, Joseph Earl Creech

Department of Agronomy and Horticulture: Faculty Publications

Forage kochia (Bassia prostrata) is used for rangeland reclamation and livestock and wildlife forage, but limited research has been conducted on its seed production. Therefore, this research evaluated the effect of harvest date on seed weight, germination, and seed yield of forage kochia subspecies virescens and grisea. Seed was harvested from individual plants for 3 years during October, November, and December. October harvest had the lightest 100-seed weights, with the November harvest slightly heavier than December, for most accessions. Cultivar Snowstorm and breeding line Sahsel, both subsp. grisea, had the greatest 100-seed weights in November, 155 …

Transient Heat Stress During Early Seed Development Primes Germination And Seedling Establishment In Rice, Kevin Begcy, Jaspreet Sandhu, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Rice yield is highly sensitive to increased temperature. Given the trend of increasing global temperatures, this sensitivity to higher temperatures poses a challenge for achieving global food security. Early seed development in rice is highly sensitive to unfavorable environmental conditions. Heat stress (HS) during this stage decreases seed size and fertility, thus reducing yield. Here, we explore the transgenerational phenotypic consequences of HS during early seed development on seed viability, germination, and establishment. To elucidate the impact of HS on the developmental events in postzygotic rice seeds, we imposed moderate (35°C) and severe (39°C) HS treatments initiated 1 day after …

Maize And Soybean Root Front Velocity And Maximum Depth In Iowa, Usa, Raziel A. Ordóñez, Michael J. Castellano, J. L. Hatfield, M. J. Helmers, Mark A. Licht, Matt Liebman, Ranae Dietzel, Rafael Martinez-Feria, Javed Iqbal, Laila A. Puntel, S. Carolina Córdova, Kaitlin Togliatti, Emily E. Wright, Sotirios V. Archontoulis

Department of Agronomy and Horticulture: Faculty Publications

Quantitative measurements of root traits can improve our understanding of how crops respond to soil and weather conditions, but such data are rare. Our objective was to quantify maximum root depth and root front velocity (RFV) for maize (Zea mays) and soybean (Glycine max) crops across a range of growing conditions in the Midwest USA. Two sets of root measurements were taken every 10–15 days: in the crop row (in-row) and between two crop rows (center-row) across six Iowa sites having different management practices such as planting dates and drainage systems, totaling 20 replicated experimental treatments. …

Sequences Involved In Plant Yield And Methods Of Using, Harkamal Walia, Dante Placido, Thomas E. Clemente

Department of Agronomy and Horticulture: Faculty Publications

Nucleic acid sequences involved in plant yield are provided, as are methods of using such nucleic acid sequences .

Identification Of Quantitative Trait Loci Conferring Resistance To Tan Spot In A Biparental Population Derived From Two Nebraska Hard Red Winter Wheat Cultivars, Gayan K. Kariyawasam, Waseem Hussain, Amanda Easterly, Mary Guttieri, Vikas Belamkar, Jesse Poland, Jorge Venegas, Stephen Baenziger, Francois Marais, Jack B. Rasmussen, Zhaohui Liu

Department of Agronomy and Horticulture: Faculty Publications

Tan spot, caused by Pyrenophora triticirepentis (Ptr), is a destructive foliar disease in all types of cultivated wheat worldwide. Genetics of tan spot resistance in wheat is complex, involving insensitivity to fungal-produced necrotrophic effectors (NEs), major resistance genes, and quantitative trait loci (QTL) conferring race-nonspecific and race-specific resistance. The Nebraska hard red winter wheat (HRWW) cultivar ‘Wesley’ is insensitive to Ptr ToxA and highly resistant to multiple Ptr races, but the genetics of resistance in this cultivar is unknown. In this study, we used a recombinant inbred line (RIL) population derived from a cross between Wesley and another …

Active-Optical Reflectance Sensing Corn Algorithms Evaluated Over The United States Midwest Corn Belt, G. M. Bean, N. R. Kitchen, J. J. Camberato, R. B. Ferguson, F. G. Fernandez, D. W. Franzen, C. A. M. Laboski, E. D. Nafziger, J. E. Sawyer, P. C. Scharf, J. Schepers, J. S. Shanahan

Department of Agronomy and Horticulture: Faculty Publications

Uncertainty exists with corn (Zea mays L.) N management due to year-to-year variation in crop N need, soil N supply, and N loss from leaching, volatilization, and denitrification. Activeoptical reflectance sensing (AORS) has proven effective in some fields for generating N fertilizer recommendations that improve N use efficiency, but locally derived (e.g., within a US state) AORS algorithms have not been tested simultaneously across a broad region. The objective of this research was to evaluate locally developed AORS algorithms across the US Midwest Corn Belt region for making in-season corn N recommendations. Forty-nine N response trials were conducted across …

Respons Pertumbuhan Dan Hasil Tanaman Hanjeli Batu (Coix Lacryma-Jobi L.) Akibat Pupuk Silika Cair Dan Paclobutrazol, Tati Nurmala, Agus Wahyudin, Ruminta

Jurnal Kultivasi

Hanjeli batu (Coix lacryma-jobi L.) merupakan salahsatu tanaman pangan alternatif yang memiliki banyak manfaat. Permasalahan utama tanaman ini adalah rendahnya produksi yang disebabkan oleh kurangnya ketersediaan unsur hara dan tinggi tanaman yang terlalu tinggi. Oleh karena itu dilakukan suatu upaya untuk meningkatkan pertumbuhan dan hasil hanjeli batu dengan pupuk silika cair dan paclobutrazol. Penelitian ini bertujuan untuk mengetahui interaksi konsentrasi pupuk silika cair dan konsentrasi paclobutrazol yang memberikan pengaruh terbaik untuk pertumbuhan dan hasil tanaman hanjeli batu (Coix lacryma-jobi L.).Percobaan dilaksanakan di Desa Pasigaran, Kecamatan Tanjungsari, Kabupaten Sumedang, pada November 2016 sampai Mei 2017. Percobaan menggunakan Rancangan Acak Kelompok (RAK) …

Respons Konduktansi Stomata Beberapa Genotipe Tebu Sebagai Parameter Toleransi Terhadap Stress Abiotik, Mochamad Arief Soleh, Ranu Manggala, Yudithia Maxiselly, Mira Ariyanti, Intan Ratna Dewi Anjarsari

Jurnal Kultivasi

Peningkatan produksi tebu saat ini akan terhambat dengan adanya fenomena pemanasan global yang disertai dengan perubahan iklim hingga mempengaruhi sebaran air hujan. Akibatnya musim hujan sering terjadi secara sporadis dan kurang dapat diprediksi. Di sisi lain kondisi lahan kebanjiran akibat genangan air berpotensi menyebabkan stress abiotik pada tanaman tebu yang secara langsung berpengaruh terhadap produktivitas tanaman. Salahsatu sifat fisiologis yang berkaitan erat dengan ketahanan stress abiotik adalah respons konduktansi stomata (gs) sebagai representatif proses metabolisme tanaman berupa fotosintesis. Beberapa varietas tebu ditanam dalam kondisi genangan air memperlihatkan perbedaan nilai gs dari 240 mmol H2O·m-2·s-1 untuk Kidang Kencana (KK) sebagai varietas …

The Effect Of Preflood Nitrogen And Flood Establishment Timing On Rice Development, Nitrogen Uptake And Grain Yield, Tyler Richmond

Graduate Theses and Dissertations

Urea-N fertilizer is typically applied at the 5-leaf stage to rice (Oryza sativa L.) grown in a dry-seeded, delayed-flood production system. How long the preflood-N can be delayed without adverse effects on yield potential is poorly understood. The research objective was to determine the effects of preflood-N application and flood establishment timing on aboveground-N content, 50% heading, yield components, and grain yield. Trials were established on silt loam soils at the Pine Tree Research Station (PTRS) and Rice Research and Extension Center (RREC) during 2015 and 2016. Urea-N was applied at 0, 45, 90, 135, and 180 kg N ha-1 …

Evaluating The Impact Of Two Contrasting Tillage Practices On Soil Properties In Central Kentucky, Emily Cook

Posters-at-the-Capitol

Farming practices such as no tillage and plowing can institute change on soil physical and chemical characteristics. In this research, the effects of long-term conventional and no-tillage systems on the selected soil properties were determined in a continuous corn system on a farm with Maury silt loam soil. These samples were taken from University of Kentucky's Research Farm (Spindletop Farm). The field used was tilled in 1969 from bluegrass sod and the first time research was conduced was in 1970. Each plot is 20 ft. by 40 ft. and for many years each plot was split with winter cover crop …

Substantial Contribution Of Genetic Variation In The Expression Of Transcription Factors To Phenotypic Variation Revealed By Erd-Gwas, Hung-Ying Lin, Qiang Liu, Xiao Li, Jinliang Yang, Sanzhen Liu, Yinlian Huang, Michael J. Scanlon, Dan Nettleton, Patrick S. Schnable

Department of Agronomy and Horticulture: Faculty Publications

Background: There are significant limitations in existing methods for the genome-wide identification of genes whose expression patterns affect traits.

Results: The transcriptomes of five tissues from 27 genetically diverse maize inbred lines were deeply sequenced to identify genes exhibiting high and low levels of expression variation across tissues or genotypes. Transcription factors are enriched among genes with the most variation in expression across tissues, as well as among genes with higher-than-median levels of variation in expression across genotypes. In contrast, transcription factors are depleted among genes whose expression is either highly stable or highly variable across genotypes. We developed a …

Estimation Of Irrigation Requirements For Drip-Irrigated Maize In A Sub-Humid Climate, Liu Yang, Hai-Shun Yang, Jiu-Sheng Li, Yan-Feng Li, Hai-Jun Yan

Department of Agronomy and Horticulture: Faculty Publications

Drip-irrigation is increasingly applied in maize (Zea mays L.) production in sub-humid region. It is critical to quantify irrigation requirements during different growth stages under diverse climatic conditions. In this study, the Hybrid-Maize model was calibrated and applied in a sub-humid Heilongjiang Province in Northeast China to estimate irrigation requirements for drip irrigated maize during different crop physiological development stages and under diverse agro-climatic conditions. Using dimensionless scales, the whole growing season of maize was divided into diverse development stages from planting to maturity. Drip-irrigation dates and irrigation amounts in each irrigation event were simulated and summarized in 30-year simulation …

Identifying Ecologically Relevant Scales Of Habitat Selection: Diel Habitat Selection In Elk, Caleb P. Roberts, James W. Cain Iii, Robert D. Cox

Department of Agronomy and Horticulture: Faculty Publications

Although organisms make resource selection decisions at multiple spatiotemporal scales, not all scales are ecologically relevant to any given organism. Ecological patterns and rhythms such as behavioral and climatic patterns may provide a consistent method for identifying ecologically relevant scales of habitat selection. Using elk (Cervus canadensis) as an example species, we sought to test the ability of behavioral patterns to empirically partition diel scales for modeling habitat selection. We used model selection to partition diel scales by shifts in dominant behavior and then used resource selection probability functions to model elk habitat selection hierarchically at diel scales within seasons. …

Effects Of Nitrogen And Phosphorus Fertilizer And Topsoil Amendment On Native Plant Cover In Roadside Revegetation Projects, Heidi L. Hillhouse, Walter H. Schacht, Jonathan M. Soper, Carol E. Wienhold

Department of Agronomy and Horticulture: Faculty Publications

Establishing vegetation on roadsides following construction can be challenging, especially for relatively slow growing native species. Topsoil is generally removed during construction, and the surface soil following construction (“cut-slope soils”) is often compacted and low in nutrients, providing poor growing conditions for vegetation. Nebraska Department of Transportation (NDOT) protocols have historically called for nitrogen (N) and phosphorus (P) fertilization when planting roadside vegetation following construction, but these recommendations were developed for cool-season grass plantings and most current plantings use slower-establishing, native warmseason grasses that may benefit less than expected from current planting protocols. We evaluated the effects of nitrogen and …

Respons Tanaman Gandum Akibat Pemberian Sitokinin Berbagai Konsentrasi Dan Waktu Aplikasi Di Dataran Medium Jatinangor, Fiky Yulianto Wicaksono, Asyifa Fiani Putri, Yuyun Yuwariah, Yudithia Maxiselly, Tati Nurmala

Jurnal Kultivasi

Pertumbuhan dan hasil gandum (Triticum aestivum L.) diketahui dapat ditingkatkan dengan pemberian sitokinin. Sitokinin berperan juga dalam menunda penuaan daun gandum dan mengurangi cekaman panas di dataran medium. Penelitian ini bertujuan untuk mengetahui pengaruh interaksi berbagai konsentrasi sitokinin dengan berbagai waktu aplikasinya terhadap pertumbuhan dan hasil tanaman gandum. Penelitian menggunakan metode percobaan yang dilakukan di kebun percobaan Ciparanje Fakultas Pertanian Universitas Padjadjaran, Jatinangor, Sumedang mulai bulan November 2016 sampai dengan Februari 2017. Rancangan percobaan yang digunakan adalah Rancangan Acak Kelompok, sementara rancangan perlakuan adalah faktorial. Perlakuan terdiri dari dua faktor, yaitu konsentrasi sitokinin (3 taraf) dan waktu aplikasi (5 taraf). …

Control Of Glyphosate-Resistant Common Ragweed (Ambrosia Artemisiifolia L.) In Glufosinate-Resistant Soybean [Glycine Max (L.) Merr], Ethann R. Barnes, Stevan Z. Knezevic, Peter H. Sikkema, John L. Lindquist, Amit J. Jhala

Department of Agronomy and Horticulture: Faculty Publications

Common ragweed emerges early in the season in Nebraska, USA and is competitive with soybean; therefore, preplant herbicides are important for effective control. Glyphosate has been used as a preplant control option; however, confirmation of glyphosate-resistant (GR) common ragweed in Nebraska necessitates evaluating other herbicide options. The objectives of this study were to (1) evaluate the efficacy of preplant (PP) herbicides followed by (fb) glufosinate alone or in tank-mixture with imazethapyr, acetochlor, or S-metolachlor applied post-emergence (POST) for control of GR common ragweed in glufosinate-resistant soybean; (2) their effect on common ragweed density, biomass, and soybean yield; and (3) the …

Pinching And Spacing Effects On Cut Sunflower (Helianthus Annuus) Production In East Texas, Rebecca B. Burnett

Electronic Theses and Dissertations

Three experiments evaluated pinching and spacing on Helianthus annuus in East Texas to determine their effects on growth and development. Experiment 1 was designed to determine the effects of pinching nodes 1, 2, 3, or 4 on ‘Pro Cut Gold’ sunflowers. Results from experiment 1 showed non-pinched plants produced marketable stem lengths and flower sizes, while pinched plants’ stem length, stem diameter, flower diameter, and disk diameter decreased compared to the non-pinched plants. The objective for experiment 2 was to evaluate pinching and spacing treatments on ‘Pro Cut Gold’ sunflowers. All spacings for non-pinched plants in experiment 2 produced marketable …

Pengaruh Konsentrasi Zat Pengatur Tumbuh Alami Dan Sintetik Terhadap Pertumbuhan Tanaman Teh (Camellia Sinensis (L.) O. Kuntze) Klon Gmb 7 Setelah Centering, Silfiya Amaliyana Saefas, Santi Rosniawaty, Yudithia Maxiselly

Jurnal Kultivasi

Tanaman teh merupakan tanaman tahunan yang memiliki organ target pucuk. Tanaman teh dapat ditingkatkan pertumbuhannya dengan pemeliharaan berupa centering dan pemberian zat pengatur tumbuh (ZPT) sitokinin pada fase TBM. Penelitian ini bertujuan untuk memperoleh konsentrasi zat pengatur tumbuh alami atau sintetik yang berpengaruh paling baik terhadap pertumbuhan tanaman teh klon GMB 7 setelah centering. Penelitian ini dilakukan pada bulan November 2016 sampai Maret 2017 di kebun percobaan Ciparanje, Fakultas Pertanian Universitas Padjadjaran, Jatinangor, Kabupaten Sumedang, Jawa Barat. Penelitian ini menguji beberapa konsentrasi zat pengatur tumbuh (ZPT) sitokinin, yaitu air kelapa sebagai ZPT alami pada konsentrasi 25%, 50%, 75% dan Benzil …

Impact Of Seed Protein Alleles From Three Soybean Sources On Seed Composition And Agronomic Traits, Lillian F. Brzostowski, Timothy I. Pruski, James Specht, Brian W. Diers

Department of Agronomy and Horticulture: Faculty Publications

Evaluation of seed protein alleles in soybean populations showed that an increase in protein concentration is generally associated with a decrease in oil concentration and yield.

Soybean [Glycine max (L.) Merrill] meal is one of the most important plant-based protein sources in the world. Developing cultivars high in seed protein concentration and seed yield is a difficult task because the traits have an inverse relationship. Over two decades ago, a protein quantitative trait loci (QTL) was mapped on chromosome (chr) 20, and this QTL has been mapped to the same position in several studies and given the confirmed QTL …

Pengaruh Dosis Silika Terhadap Karakter Fisiologı Dan Hasil Tanaman Padi (Oryza Sativa L.) Kultivar Lokal Poso (Kultıvar 36-Super Dan Tagolu), Wan Priando Tampoma, Tati Nurmala, Meddy Rachmadi

Jurnal Kultivasi

Padi (Oryza sativa L.) merupakan salah satu jenis tanaman yang memegang peran penting di Indonesia dalam memenuhi kebutuhan pangan. Tanaman padi kultivar lokal merupakan salah satu jenis padi yang memiliki poduktivitas rendah. Pemberian silika pada pertanaman padi dapat membantu mengoptimalkan pertumbuhan dan hasil tanaman padi. Tujuan penelitian ini adalah untuk mengetahui pengaruh silika terhadap karakter agronomi kultivar lokal Poso. Rancangan percobaan yang digunakan dalam penelitian ini adalah menggunakan Rancangan Petak Terbagi (RPT). Faktor pertama sebagai petak utama terdiri dua taraf perlakuan yaitu K1 (Kultivar 36-Super) dan K2 (Kultivar Tagolu). Sedangkan faktor ke dua sebagai anak petak terdiri atas 4 taraf …

Mushroom Inoculation On Switchgrass Feedstock During Storage: Effects Of Subsequent Pre-Processing For Intended Biofuels Production, Amandeep Singh Turay

Graduate Theses and Dissertations

The objective of this project was to examine the effect of fungal treatment and liquid hot water pretreatment of switchgrass combine in view of increasing glucose release. The fungal treatment consisted of incubating Pleurotus ostreatus in square switchgrass bales, at 50% moisture content for 25 days, 54 days, and 82 days. The digestibility of the switchgrass biomass was subsequently evaluated using Accelerase 1500 enzyme. Lignin is an important barrier to enzymatic hydrolysis, and it was stipulated that incubation with P. ostreatus would disrupt plant cell walls, resulting in enhanced saccharification. Three different concentrations of P. ostreatus were evaluated: 0%, 2%, …

Molecular And Culture-Based Assessment Of Root/Crown Rot Fungal/Oomycete Complex Of Bean In Mozambique, Suzana Vanessa Ismael Fernandes

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

Dry edible beans (Phaseolus vulgaris) play an important role in food security, alleviating hunger and malnutrition and adding value to the economy in Mozambique. Recently, root/crown rot (RCR) has caused yield losses in bean fields in Mozambique. A diverse taxa of fungi and oomycetes have been associated with RCR. However, in Mozambique little information on root rot is available. The purpose of this study is to use Illumina sequencing platform, polymerase chain reaction (PCR) and culture-based methods to identify the primary pathogens associated with RCR in Mozambique. A total of 88 plants showing symptoms of RCR disease were …

Protocol For Enrichment Of The Membrane Proteome Of Mature Tomato Pollen, Puneet Paul, Palak Chaturvedi, Anida Mesihovic, Arindam Ghatak, Wolfram Weckwerth, Enrico Schleiff

Department of Agronomy and Horticulture: Faculty Publications

We established and elaborated on a method to enrich the membrane proteome of mature pollen from economically relevant crop using the example of Solanum lycopersicum (tomato). To isolate the pollen protein fraction enriched in membrane proteins, a high salt concentration (750 mM of sodium chloride) was used. The membrane protein-enriched fraction was then subjected to shotgun proteomics for identification of proteins, followed by in silico analysis to annotate and classify the detected proteins.

Transcriptomic Resources For The Medicinal Legume Mucuna Pruriens: De Novo Transcriptome Assembly, Annotation, Identification And Validation Of Est-Ssr Markers, N. Sathyanarayana, Ranjith Kumar Pittala, Pankaj Kumar Tripathi, Ratan Chopra, Heikham Russiachand Singh, Vikas Belamkar, Pardeep Kumar Bhardwaj, Jeff J. Doyle, Ashley N. Egan

Department of Agronomy and Horticulture: Faculty Publications

Background:

The medicinal legume Mucuna pruriens (L.) DC. has attracted attention worldwide as a source of the anti-Parkinson’s drug L-Dopa. It is also a popular green manure cover crop that offers many agronomic benefits including high protein content, nitrogen fixation and soil nutrients. The plant currently lacks genomic resources and there is limited knowledge on gene expression, metabolic pathways, and genetics of secondary metabolite production. Here, we present transcriptomic resources for M. pruriens, including a de novo transcriptome assembly and annotation, as well as differential transcript expression analyses between root, leaf, and pod tissues. We also develop microsatellite markers …

A Comprehensive Analysis Of Alternative Splicing In Paleopolyploid Maize, Wenbin Mei, Sanzhen Liu, James C. Schnable, Cheng-Ting Yeh, Nathan M. Springer, Patrick S. Schnable, William Brad Barbazuk

Department of Agronomy and Horticulture: Faculty Publications

Identifying and characterizing alternative splicing (AS) enables our understanding of the biological role of transcript isoform diversity. This study describes the use of publicly available RNA-Seq data to identify and characterize the global diversity of AS isoforms in maize using the inbred lines B73 and Mo17, and a related species, sorghum. Identification and characterization of AS within maize tissues revealed that genes expressed in seed exhibit the largest differential AS relative to other tissues examined. Additionally, differences in AS between the two genotypes B73 and Mo17 are greatest within genes expressed in seed. We demonstrate that changes in the level …

Evaluation And Association Analysis Of Cowpea Salt Tolerance, Waltram Second Ravelombola

Graduate Theses and Dissertations

Cowpea [Vigna unguiculata (L.) Walp.] (2n=2x=22) is a leguminous crop providing inexpensive protein for human consumption that can be grown worldwide. Salinity is one of the major threats to cowpea production, particularly in semi-arid regions of Africa. Salinity significantly affects seed germination and decreases pod yield in cowpea. However, little has been done to provide farmers salt-tolerant cowpea cultivars. Knowledge on the genetics of cowpea salt tolerance is very limited. This study aimed to:(1) evaluate cowpea salt tolerance at germination stage, (2) evaluate cowpea salt tolerance at seedling stage, (3) conduct an association study for cowpea salt tolerance at germination …

High Throughput In Vivo Analysis Of Plant Leaf Chemical Properties Using Hyperspectral Imaging, Piyush Pandey, Yufeng Ge, Vincent Stoerger, James C. Schnable

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

The possibility of predicting plant leaf chemical properties using hyperspectral images was studied. Sixty maize and 60 soybean plants were used, and two experiments were conducted: one with water limitation and the second with nutrient limitation, with the purpose of creating wide ranges of these chemical properties in plant leaf tissues. A hyperspectral imaging system with a spectral range from 550 to 1700 nm was used to acquire plant images in a high throughput fashion (plants placed on an automated conveyor belt). Leaf chemical properties were measured in the laboratory. Partial least squares regression was implemented on spectral data to …

Emergence, Competition, And Management Of Glyphosate-Resistant Common Ragweed (Ambrosia Artemisiifolia L.) In Nebraska Soybean, Ethann R. Barnes

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

Common ragweed (Ambrosia artemisiifolia L.) is a competitive annual broadleaf weed in soybean (Glycine max) production fields throughout North America. The recent confirmation of glyphosate-resistant common ragweed in Nebraska justified the need to assess the emergence pattern and competitive ability of common ragweed in soybean and to evaluate alternative herbicide programs for effective management. The objectives of this research were to: 1) evaluate the effect of tillage and develop a predictive model for the emergence pattern of common ragweed in Nebraska; 2) model the competitive interaction between soybean and common ragweed as influenced by density and irrigation …

Modeling Gross Primary Production Of Midwest Maize And Soybean Croplands With Satellite And Gridded Weather Data, Gunnar Malek-Madani

Department of Geography: Dissertations, Theses, and Student Research

The gross primary production (GPP) metric is useful in determining trends in the terrestrial carbon cycle. Models that determine GPP utilizing the light use efficiency (LUE) approach in conjunction with biophysical parameters that account for local weather conditions and crop specific factors are beneficial in that they combine the accuracy of the biophysical model with the versatility of the LUE model. One such model developed using in situ data was adapted to operate with remote sensing derived leaf area index (LAI) data and gridded weather datasets. The model, known as the Light Use Efficiency GPP Model (EGM), uses a four …