Agronomy and Crop Sciences Commons^™

Frost: Frequently Asked Questions, Department Of Primary Industries And Regional Development, Western Australia

Grain and other field crops published reports

Frequently asked questions regarding frost from the National Frost Initiative.

Effects Of Fertilizer And Shade Management On Nitrogen Mineralization, Nitrifying Microbial Abundance And Nitrogen-Fixing Capacity Of Erythrina Poeppigiana In Coffee (Coffea Arabica) Agroforestry Systems In Costa Rica, Stuart E. Barker Iii

College of Graduate Studies: Theses & Dissertations

Worldwide chemical fertilizer use has increased by four times during the last 50 years. Conventional agricultural systems have a high nitrifying nature, resulting in a loss of nearly 70% of overall nitrogen (N) fertilizer inputs, an estimated economic loss of $81 billion. Over application of fertilizer is rampant in tropical developing nations in Central America, where coffee is major crop. Agroforestry offers ecologically sustainable land management strategies that promote the provision of ecosystem services such as, protection of biodiversity, climate change mitigation, and water and soil regulation. When legume trees are incorporated as the shade tree in coffee production, direct …

Pollen-Mediated Gene Flow From Glyphosate-Resistant Common Waterhemp (Amaranthus Rudis Sauer): Consequences For The Dispersal Of Resistance Genes, Debalin Sarangi, Andrew J. Tyre, Eric L. Patterson, Todd A. Gaines, Suat Irmak, Stevan Z. Knezevic, John L. Lindquist, Amit J. Jhala

Department of Agronomy and Horticulture: Faculty Publications

Gene flow is an important component in evolutionary biology; however, the role of gene flow in dispersal of herbicide-resistant alleles among weed populations is poorly understood. Field experiments were conducted at the University of Nebraska-Lincoln to quantify pollen-mediated gene flow (PMGF) from glyphosate-resistant (GR) to -susceptible (GS) common waterhemp using a concentric donorreceptor design. More than 130,000 common waterhemp plants were screened and 26,199 plants were confirmed resistant to glyphosate. Frequency of gene flow from all distances, directions, and years was estimated with a double exponential decay model using Generalized Nonlinear Model (package gnm) in R. PMGF declined by 50% …

Stress-Responsive Pathways And Small Rna Changes Distinguish Variable Developmental Phenotypes Caused By Msh1 Loss, Mon-Ray Shao, Sunil Kumar Kenchanmane Raju, John D. Laurie, Robersy Sanchez, Sally A. Mackenzie

Department of Agronomy and Horticulture: Faculty Publications

Background: Proper regulation of nuclear-encoded, organelle-targeted genes is crucial for plastid and mitochondrial function. Among these genes, MutS Homolog 1 (MSH1) is notable for generating an assortment of mutant phenotypes with varying degrees of penetrance and pleiotropy. Stronger phenotypes have been connected to stress tolerance and epigenetic changes, and in Arabidopsis T-DNA mutants, two generations of homozygosity with the msh1 insertion are required before severe phenotypes begin to emerge. These observations prompted us to examine how msh1 mutants contrast according to generation and phenotype by profiling their respective transcriptomes and small RNA populations.

Results: Using RNA-seq, we analyze …

Patterns Of Gene Expression In Western Corn Rootworm (Diabrotica Virgifera Virgifera) Neonates, Challenged With Cry34ab1, Cry35ab1 And Cry34/35ab1, Based On Next-Generation Sequencing, Haichuan Wang, Seong-Il Eyun, Kanika Arora, Sek Yee Tan, Premchand Gandra, Etsuko N. Moriyama, Chitvan Khajuria, Jessica D. Jurzenski, Huarong Li, Maia Donahue, Kenneth E. Narva, Blair Siegfried

Department of Agronomy and Horticulture: Faculty Publications

With Next Generation Sequencing technologies, high-throughput RNA sequencing (RNAseq) was conducted to examine gene expression in neonates of Diabrotica virgifera virgifera (LeConte) (Western Corn Rootworm, WCR) challenged with individual proteins of the binary Bacillus thuringiensis insecticidal proteins, Cry34Ab1 and Cry35Ab1, and the combination of Cry34/Cry35Ab1, which together are active against rootworm larvae. Integrated results of three different statistical comparisons identified 114 and 1300 differentially expressed transcripts (DETs) in the Cry34Ab1 and Cry34/35Ab1 treatment, respectively, as compared to the control. No DETs were identified in the Cry35Ab1 treatment. Putative Bt binding receptors previously identified in other insect species were not identified …

Allelic Variants Of Oshkt1;1 Underlie The Divergence Between Indica And Japonica Subspecies Of Rice (Oryza Sativa) For Root Sodium Content, Malachy T. Campbell, Nonoy Bandillo, Fouad Razzaq A. Al Shiblawi, Sandeep Sharma, Kan Liu, Qian Du, Aaron J. Schmitz, Chi Zhang, Anne-Alienor Very, Aaron J. Lorenz, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Salinity is a major factor limiting crop productivity. Rice (Oryza sativa), a staple crop for the majority of the world, is highly sensitive to salinity stress. To discover novel sources of genetic variation for salt tolerance-related traits in rice, we screened 390 diverse accessions under 14 days of moderate (9 dS m^-1) salinity. In this study, shoot growth responses to moderate levels of salinity were independent of tissue Na⁺ content. A significant difference in root Na+ content was observed between the major subpopulations of rice, with indica accessions displaying higher root Na⁺ and japonica …

Regeneration And Invasion Of Cottonwood Riparian Forest Following Wildfire, Carissa L. Wonkka, Dirac L. Twidwell Jr., Christine H. Bielski, Craig R. Allen, Michael C. Stambaugh

Department of Agronomy and Horticulture: Faculty Publications

Populus deltoides is considered to be a weak resprouter and highly susceptible to wildfire, but few post-wildfire studies have tracked P. deltoides response and resprouting within the Great Plains of North America. Following a wildfire in southwestern Kansas, U.S.A., we surveyed burned and unburned areas of a cottonwood riparian forest along the Cimarron River that included a major understory invader, tamarisk (Tamarix ramosissima Ledeb.). We tested the following hypotheses, which are consistent with the current understanding of P. deltoides response to wildfire in the Great Plains: (1) regeneration of P. deltoides will be low in areas burned by the …

Robust Spatial Frameworks For Leveraging Research On Sustainable Crop Intensification, Patricio Grassini, Cameron M. Pittelkow, Kenneth Cassman, Haishun S. Yang, Sotirios Archontoulis, Mark Licht, Kendall R. Lamkey, Ignacio A. Ciampitti, Jeffrey A. Coulter, Sylvie M. Brouder, Jeffrey J. Volenec, Noemi Guindin-Garcia

Department of Agronomy and Horticulture: Faculty Publications

Meeting demand for food, fiber, feed, and fuel in a world with 9.7 billion people by 2050 without negative environmental impact is the greatest scientific challenge facing humanity. We hypothesize that this challenge can only be met with current and emerging technologies if guided by proactive use of a broad array of relevant data and geospatial scaling approaches to ensure local to global relevance for setting research priorities and implementing agricultural systems responsive to real-time status of weather, soils, crops, and markets. Despite increasing availability of field-scale agricultural data, robust spatial frameworks are lacking to convert these data into actionable …

Metabolism Of 2,4-Dichlorophenoxyacetic Acid Contributes To Resistance In A Common Waterhemp (Amaranthus Tuberculatus) Population, Marcelo R. A. Figueiredo, Lacy J. Leibhart, Zachary J. Reicher, Patrick J. Tranel, Scott J. Nissen, Philip Westra, Mark L. Bernards, Greg R. Kruger, Todd A. Gaines, Mithila Jugulam

Department of Agronomy and Horticulture: Faculty Publications

BACKGROUND: Synthetic auxins such as 2,4-D have been widely used for selective control of broadleaf weeds since the mid-1940s. In 2009, an Amaranthus tuberculatus (common waterhemp) population with 10-fold resistance to 2,4-D was found in Nebraska, USA. The 2,4-D resistance mechanism was examined by conducting [¹⁴C] 2,4-D absorption, translocation and metabolism experiments.

RESULTS: No differences were found in 2,4-D absorption or translocation between the resistant and susceptible A. tuberculatus. Resistant plants metabolized [¹⁴C] 2,4-D more rapidly than did susceptible plants. The half-life of [¹⁴C] 2,4-D in susceptible plants was 105 h, compared to …

Assessment Of Canopy Chlorophyll Content Retrieval In Maize And Soybean: Implications Of Hysteresis On The Development Of Generic Algorithms, Yi Peng, Anthony L. Nguy-Robertson, Timothy J. Arkebauer, Anatoly A. Gitelson

Department of Agronomy and Horticulture: Faculty Publications

Canopy chlorophyll content (Chl) closely relates to plant photosynthetic capacity, nitrogen status and productivity. The goal of this study is to develop remote sensing techniques for accurate estimation of canopy Chl during the entire growing season without re-parameterization of algorithms for two contrasting crop species, maize and soybean. These two crops represent different biochemical mechanisms of photosynthesis, leaf structure and canopy architecture. The relationships between canopy Chl and reflectance, collected at close range and resampled to bands of the Multi Spectral Instrument (MSI) aboard Sentinel-2, were analyzed in samples taken across the entirety of the growing seasons in three irrigated …

Can Yield Gap Analysis Be Used To Inform R & D Prioritisation?, P. A. J. Van Oort, K. Saito, I. Dieng, P. Grassini, K. G. Cassman, M. K. Van Ittersum

Department of Agronomy and Horticulture: Faculty Publications

The phrase “biggest bang for a buck” is associated with the policy making question that governments and development agencies face: “Where and which crops should receive highest priority for improving local and global food supply?”. A first step of prioritisation is to identify region x crop combinations for which high impact can be anticipated. We developed a new method for this prioritisation exercise and applied it to data from the Global Yield Gap and Water Productivity Atlas (GYGA). Our prioritisation distinguishes between two policy objectives (humanitarian and economic) and builds upon the relative yield gap and climate risk. Results of …

Genotype, Environment, Seeding Rate, And Top-Dressed Nitrogen Effects On End-Use Quality Of Modern Nebraska Winter Wheat, Madhav Bhatta, Teshome Regassa, Devin J. Rose, P. Stephen Baenziger, Kent M. Eskridge, Dipak K. Santra, Rachana Poudel

Department of Agronomy and Horticulture: Faculty Publications

Background: Fine-tuning production inputs such as seeding rate, nitrogen (N), and genotype may improve end-use quality of hard red winter wheat (Triticum aestivium L.) when growing conditions are unpredictable. Studies were conducted at the Agronomy Research Farm (ARF; Lincoln, NE, USA) and the High Plains Agricultural Laboratory (HPAL; Sidney, NE, USA) in 2014 and 2015 in Nebraska, USA, to determine the effects of genotype (6), environment (4), seeding rate (3), and flag leaf top-dressed N (0 and 34 kg N ha⁻¹) on the end-use quality of winter wheat.

Results: End-use quality traits were influenced by environment, genotype, …

Using An Active-Optical Sensor To Develop An Optimal Ndvi Dynamic Model For High-Yield Rice Production (Yangtze, China), Xiaojun Liu, Richard B. Ferguson, Hengbiao Zheng, Qiang Cao, Yongchao Tian, Weixing Cao, Yan Zhu

Department of Agronomy and Horticulture: Faculty Publications

The successful development of an optimal canopy vegetation index dynamic model for obtaining higher yield can offer a technical approach for real-time and nondestructive diagnosis of rice (Oryza sativa L) growth and nitrogen (N) nutrition status. In this study, multiple rice cultivars and N treatments of experimental plots were carried out to obtain: normalized difference vegetation index (NDVI), leaf area index (LAI), above-ground dry matter (DM), and grain yield (GY) data. The quantitative relationships between NDVI and these growth indices (e.g., LAI, DM and GY) were analyzed, showing positive correlations. Using the normalized modeling method, an appropriate NDVI simulation model …

Genomic Prediction With Pedigree And Genotype X Environment Interaction In Spring Wheat Grown In South And West Asia, North Africa, And Mexico, Sivakumar Sukumaran, José Crossa, Diego Jarquin, Marta Lopes, Matthew P. Reynolds

Department of Agronomy and Horticulture: Faculty Publications

Developing genomic selection (GS) models is an important step in applying GS to accelerate the rate of genetic gain in grain yield in plant breeding. In this study, seven genomic prediction models under two cross-validation (CV) scenarios were tested on 287 advanced elite spring wheat lines phenotyped for grain yield (GY), thousand-grain weight (GW), grain number (GN), and thermal time for flowering (TTF) in 18 international environments (year-location combinations) in major wheat-producing countries in 2010 and 2011. Prediction models with genomic and pedigree information included main effects and interaction with environments. Two random CV schemes were applied to predict a …

Shifts In Microbial Communities In Soil, Rhizosphere And Roots Of Two Major Crop Systems Under Elevated Co2 And O3, Peng Wang, Ellen L. Marsh, Elizabeth A. Ainsworth, Andrew D. B. Leakey, Amy M. Sheflin, Daniel P. Schachtman

Department of Agronomy and Horticulture: Faculty Publications

Rising atmospheric concentrations of CO₂ and O₃ are key features of global environmental change. To investigate changes in the belowground bacterial community composition in response to elevated CO₂ and O₃ (eCO₂ and eO₃) the endosphere, rhizosphere and soil were sampled from soybeans under eCO2 and maize under eO₃. The maize rhizosphere and endosphere α-diversity was higher than soybean, which may be due to a high relative abundance of Rhizobiales. Only the rhizosphere microbiome composition of the soybeans changed in response to eCO₂, associated with an increased abundance of nitrogen …

Effect Of The National Accelerated Agricultural Inputs Access Subsidy Program On Fertilizer Usage And Food Production In Kakamega County, Western Kenya, Abednego Kiwia Mavuthu

Walden Dissertations and Doctoral Studies

Despite 25 years of concerted efforts by African governments to adopt consistent policies for increasing food production, hunger and poverty are still prevalent in the continent. Using Bernanke's conceptualization of the credit channel theory of monetary policy, the purpose of this correlational study was to investigate whether a subsidy program, the National Accelerated Agricultural Inputs Access Program (NAAIAP), affected the rates of fertilizer usage and food production in Kakamega County, Western Kenya. Purposive stratified sampling was used to select 114 participants consisting of 72 farmers in each of the 2 groups: NAAIAP beneficiaries and nonbeneficiaries. Participants completed a survey on …

Influence Of Olfactory And Visual Cover On Nest Site Selection And Nest Success For Grassland-Nesting Birds, Dillon T. Fogarty, Dwayne Elmore, Samuel D. Fuhlendorf, Scott R. Loss

Department of Agronomy and Horticulture: Faculty Publications

Habitat selection by animals is influenced by and mitigates the effects of predation and environmental extremes. For birds, nest site selection is crucial to offspring production because nests are exposed to extreme weather and predation pressure. Predators that forage using olfaction often dominate nest predator communities; therefore, factors that influence olfactory detection (e.g., airflow and weather variables, including turbulence and moisture) should influence nest site selection and survival. However, few studies have assessed the importance of olfactory cover for habitat selection and survival. We assessed whether ground-nesting birds select nest sites based on visual and/or olfactory cover. Additionally, we assessed …

Jasmonoyl-L-Tryptophan Disrupts Iaa Activity Through The Aux1 Auxin Permease, Paul E. Staswick, Martha Rowe, Edgar P. Spalding, Bessie L. Splitt

Department of Agronomy and Horticulture: Faculty Publications

Amide-linked conjugates between tryptophan (Trp) and jasmonic (JA) or indole-3- acetic (IAA) acids interfered with gravitropism and other auxin-dependent activities in Arabidopsis, but the mechanism was unclear. To identify structural features necessary for activity several additional Trp conjugates were synthesized. The phenylacetic acid (PAA) conjugate was active, while several others were not. Common features of active conjugates is that they have ring structures that are linked to Trp through an acetic acid side chain, while longer or shorter linkages are inactive or less active. A dominant mutant, called tryptophan conjugate response1-D that is insensitive to JA-Trp, but still sensitive …

Interaction Of 2,4-D Or Dicamba With Glufosinate For Control Of Glyphosate-Resistant Giant Ragweed (Ambrosia Trifida L.) In Glufosinate-Resistant Maize (Zea Mays L.), Zahoor A. Ganie, Amit J. Jhala

Department of Agronomy and Horticulture: Faculty Publications

Glyphosate-resistant (GR) giant ragweed is a problematic broadleaf weed in crops including maize and soybean in the Midwestern United States. Commercialization of crops with 2,4-D or dicamba and glufosinate resistance will allow post-emergence (POST) applications of these herbicides. Therefore, information is needed on how 2,4-D/dicamba will interact with glufosinate in various rate combinations. The objectives of this study were to evaluate the interaction of glufosinate plus 2,4-D and/or dicamba for control of GR giant ragweed, and to determine their effect on GR giant ragweed density, biomass, maize injury, and yield. Field experiments were conducted in 2013 and 2014 in a …

High-Throughput Profiling And Analysis Of Plant Responses Over Time To Abiotic Stress, Kira M. Veley, Jeffrey C. Berry, Sarah J. Fentress, Daniel P. Schachtman, Ivan Baxter, Rebecca Bart

Department of Agronomy and Horticulture: Faculty Publications

Sorghum (Sorghum bicolor (L.) Moench) is a rapidly growing, high-biomass crop prized for abiotic stress tolerance. However, measuring genotype-by-environment (G x E) interactions remains a progress bottleneck. We subjected a panel of 30 genetically diverse sorghum genotypes to a spectrum of nitrogen deprivation and measured responses using high-throughput phenotyping technology followed by ionomic profiling. Responses were quantified using shape (16 measurable outputs), color (hue and intensity), and ionome (18 elements). We measured the speed at which specific genotypes respond to environmental conditions, in terms of both biomass and color changes, and identified individual genotypes that perform most favorably. With this …