Plant Biology Commons^™

Long-Term Tillage Impact On Soil Hydraulic Properties, Humberto Blanco-Canqui, Brian J. Weinhold, Virginia L. Jin, Marty R. Schmer, Leonard C. Kibet

Department of Agronomy and Horticulture: Faculty Publications

An improved understanding of the impact of tillage systems on soil hydraulic properties is necessary to conserve and manage soil water under a changing climate. The objective of this study was to specifically measure soil hydraulic properties (total porosity, water infiltration, saturated hydraulic conductivity, and water retention characteristics) in no-till, chisel plow, disk, and moldboard plow systems under rainfed continuous corn (Zea mays L.) after 35 yr on silty clay loam soils in eastern Nebraska. We measured ponded water infiltration (positive soil water pressure) and tension (-1 kPa matric potential) infiltration to exclude macropore (>125 mm diameter) flow. …

Reversing Resistance To Tembotrione In An Amaranthus Tuberculatus (Var. Rudis) Population From Nebraska, Usa With Cytochrome P450 Inhibitors, Maxwel C. Oliveira, Todd A. Gaines, Franck E. Dayan, Eric L. Patterson, Amit J. Jhala, Stevan Z. Knezevic

Department of Agronomy and Horticulture: Faculty Publications

Background: A population of Amaranthus tuberculatus (var. rudis) was confirmed resistant to 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibitor herbicides (mesotrione, tembotrione, and topramezone) in a seed corn/soybean rotation in Nebraska. Further investigation confirmed a non-target-site resistance mechanism in this population. The main objective of this study was to explore the role of cytochrome P450 inhibitors in restoring the efficacy of HPPD-inhibitor herbicides on the HPPD-inhibitor resistant A. tuberculatus population from Nebraska, USA (HPPD-R).

Background: A population of Amaranthus tuberculatus (var. rudis) was confirmed resistant to 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibitor herbicides (mesotrione, tembotrione, and topramezone) in a seed corn/soybean rotation in Nebraska. Further investigation confirmed …

Tgbs® Genotyping-By-Sequencing Enables Reliable Genotyping Of Heterozygous Loci, Alina Ott, Sanzhen Liu, James C. Schnable, Cheng-Ting 'Eddy' Yeh, Kai-Sin Wang, Patrick S. Schnable

Department of Agronomy and Horticulture: Faculty Publications

Conventional genotyping-by-sequencing (cGBS) strategies suffer from high rates of missing data and genotyping errors, particularly at heterozygous sites. tGBS® genotyping-by-sequencing is a novel method of genome reduction that employs two restriction enzymes to generate overhangs in opposite orientations to which (single-strand) oligos rather than (double-stranded) adaptors are ligated. This strategy ensures that only doubledigested fragments are amplified and sequenced. The use of oligos avoids the necessity of preparing adaptors and the problems associated with inter-adaptor annealing/ligation. Hence, the tGBS protocol simplifies the preparation of high-quality GBS sequencing libraries. During polymerase chain reaction (PCR) amplification, selective nucleotides included at the 3'-end …

Using An Unmanned Aerial Vehicle To Evaluate Nitrogen Variability And Height Effect With An Active Crop Canopy Sensor, Brian Krienke, Richard B. Ferguson, Michael Schlemmer, Kyle Holland, David B. Marx, Kent M. Eskridge

Department of Agronomy and Horticulture: Faculty Publications

Ground-based active sensors have been used in the past with success in detecting nitrogen (N) variability within maize production systems. The use of unmanned aerial vehicles (UAVs) presents an opportunity to evaluate N variability with unique advantages compared to ground-based systems. The objectives of this study were to: determine if a UAV was a suitable platform for use with an active crop canopy sensor to monitor in-season N status of maize, if UAV’s were a suitable platform, is the UAV and active sensor platform a suitable substitute for current handheld methods, and is there a height effect that may be …

Plantcv V2: Image Analysis Software For High-Throughput Plant Phenotyping, Malia A. Gehan, Noah Fahlgren, Arash Abbasi, Jeffrey C. Berry, Steven T. Callen, Leonardo Chavez, Andrew N. Doust, Max J. Feldman, Kerrigan B. Gilbert, John G. Hodge, J. Steen Hoyer, Andy Lin, Suxing Liu, César Lizárraga, Argelia Lorence, Michael Miller, Eric Platon, Monica Tessman, Tony Sax

Department of Agronomy and Horticulture: Faculty Publications

Systems for collecting image data in conjunction with computer vision techniques are a powerful tool for increasing the temporal resolution at which plant phenotypes can be measured non-destructively. Computational tools that are flexible and extendable are needed to address the diversity of plant phenotyping problems. We previously described the Plant Computer Vision (PlantCV) software package, which is an image processing toolkit for plant phenotyping analysis. The goal of the PlantCV project is to develop a set of modular, reusable, and repurposable tools for plant image analysis that are open-source and community-developed. Here we present the details and rationale for major …

Dissecting The Genetic Basis Of Local Adaptation In Soybean, Nonoy B. Bandillo, Justin E. Anderson, Michael B. Kantar, Robert M. Stupar, James E. Specht, George L. Graef, Aaron J. Lorenz

Department of Agronomy and Horticulture: Faculty Publications

Soybean (Glycine max) is the most widely grown oilseed in the world and is an important source of protein for both humans and livestock. Soybean is widely adapted to both temperate and tropical regions, but a changing climate demands a better understanding of adaptation to specific environmental conditions. Here, we explore genetic variation in a collection of 3,012 georeferenced, locally adapted landraces from a broad geographical range to help elucidate the genetic basis of local adaptation. We used geographic origin, environmental data and dense genome-wide SNP data to perform an environmental association analysis and discover loci displaying steep …

Comparison Of Organic And Integrated Nutrient Management Strategies For Reducing Soil N2O Emissions, Rebecca F. Graham, Samuel E. Wortman, Cameron M. Pittelkow

Department of Agronomy and Horticulture: Faculty Publications

To prevent nutrient limitations to crop growth, nitrogen is often applied in agricultural systems in the form of organic inputs (e.g., crop residues, manure, compost, etc.) or inorganic fertilizer. Inorganic nitrogen fertilizer has large environmental and economic costs, particularly for low-input smallholder farming systems. The concept of combining organic, inorganic, and biological nutrient sources through Integrated Nutrient Management (INM) is increasingly promoted as a means of improving nutrient use efficiency by matching soil nutrient availability with crop demand. While the majority of previous research on INM has focused on soil quality and yield, potential climate change impacts have rarely been …

Rooting For Food Security In Sub-Saharan Africa, Nicolas Guilpart, Patricio Grassini, Justin Van Wart, Haishun Yang, Martin K. Van Ittersum, Lenny G.J. Van Bussel, Joost Wolf, Lieven Claessens, Johan G.B. Leenaars, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

There is a persistent narrative about the potential of Sub-Saharan Africa (SSA) to be a ‘grain breadbasket’ because of large gaps between current low yields and yield potential with good management, and vast land resources with adequate rainfall. However, rigorous evaluation of the extent to which soils can support high, stable yields has been limited by lack of data on rootable soil depth of sufficient quality and spatial resolution. Here we use location-specific climate data, a robust spatial upscaling approach, and crop simulation to assess sensitivity of rainfed maize yields to root-zone water holding capacity. We find that SSA could …

Supplemental Material For: Multi-Site Evaluation Of Apex For Water Quality: Ii. Regional Parameterization, Nathan O. Nelson, Claire Baffaut, John A. Lory, G.M.M.M. Anomaa Senaviratne, Ammar B. Bhandari, Ranjith P. Udawatta, Daniel W. Sweeney, Matt J. Helmers, Mike W. Van Liew, Antonio P. Mallarino, Charles S. Wortmann

Department of Agronomy and Horticulture: Faculty Publications

Model performance was assessed using Nash-Sutcliffe model efficiency (NSE), coefficient of determination (r²), and percent bias (PBIAS) as defined by Moriasi et al. (2007 and 2015). Threshold values indicating acceptable model performance based on these statistics are dependent on the spatial and temporal scales of the data, water quality constituents of interest, and the modeling objectives (Moriasi et al., 2015). Although some standard values have been suggested (Moriasi et al., 2007 and 2015), considerable variability exist in the published literature. For instance Ramanarayan et al. (1997) considered r² >0.5 and NSE >0.40 as satisfactory for simulation of …

Author Correction: Genome-Guided Phylo-Transcriptomic Methods And The Nuclear Phylogenetic Tree Of The Paniceae Grasses, Jacob D. Washburn, James C. Schnable, Gavin C. Conant, Thomas P. Brutnell, Ying Shao, Yang Zhang, Martha Ludwig, Gerrit Davidse, J. Chris Pires

Department of Agronomy and Horticulture: Faculty Publications

The original version of this Article contained an error in the title of the paper, where the word “Phylogenetic” was incorrectly given as “Phylogentic”. This has now been corrected in the PDF and HTML versions of the Article, and in the accompanying Supplementary Information file.

Lettuce Learn: Student Reflections On Building And Sustaining A Community Donation Garden, Hannah Dankbar, Emily K. Zimmerman, Carrie Chennault, Andrea D. Basche, Jacqueline Ann Nester, Maritza Pierre, Gabrielle Roesch-Mcnally

Department of Agronomy and Horticulture: Faculty Publications

This article emerged from conversations that we and fellow graduate students have had in building a community donation garden. We created the garden with a vision of enacting food justice in our community, but over the past four years we have experienced complexities with our vision. In this article, we share the complexities with which we have wrestled, how we have encouraged thoughtful dialogue among fellow scholars about these shortcomings and the intricate workings of the agrifood system, and the lessons we have learned through these experiences as early-career scholar-activists. This article represents our collective and individual voices as graduate …

Leveraging Agroecology For Solutions In Food, Energy, And Water, Marcia Delonge, Andrea D. Basche

Department of Agronomy and Horticulture: Faculty Publications

Global agriculture is facing growing challenges at the nexus of interconnected food, energy and water systems, including but not limited to persistent food insecurity and diet-related diseases; growing demands for energy and consequences for climate change; and declining water resources, water pollution, floods and droughts. Further, soil degradation and biodiversity loss are both triggers for and consequences of these problems. In this commentary, we argue that expanding agroecological principles, tools, and technologies and enhancing biological diversity can address these challenges and achieve better socioeconomic outcomes. Agroecology is often described as multi- or transdiscplinary, and applies ecological principles to the design …

Improving Water Resilience With More Perennially Based Agriculture, Andrea D. Basche, Oliver F. Edelson

Department of Agronomy and Horticulture: Faculty Publications

Land conversion from natural to managed ecosystems, while necessary for food production, continues to occur at high rates with significant water impacts. Further, increased rainfall variability exposes agricultural systems to impacts from flood and drought events. In many regions, water limitations are overcome through technological approaches such as irrigation and tile drainage, which may not be sustainable in the long term. A more sustainable approach to combat episodes of floods and droughts is to increase soil water storage and the overall green water efficiency of agroecosystems. Agricultural practices that promote “continuous living cover,” such as perennial grasses, agroforestry and cover …

The Impact Of Continuous Living Cover On Soil Hydrologic Properties: A Meta-Analysis, Andrea D. Basche, Marcia Delonge

Department of Agronomy and Horticulture: Faculty Publications

Increased rainfall variability due to climate change threatens the efficacy of critical soil ecosystem services. One strategy to negate effects of too much or not enough rainfall is to improve soil water properties. Practices that offer “continuous living cover” can enhance soil water storage and other soil hydrologic properties relative to annual crop systems, but to what extent such benefits can accrue, under different conditions, remains under-quantified. To address these uncertainties, we conducted a meta-analysis that included 27 studies representing 93 paired observations measuring two soil hydrologic properties: porosity and the water retained at field capacity. All experiments compared the …

Research Topics To Scale Up Cover Crop Use: Reflections From Innovative Iowa Farmers, Andrea D. Basche, Gabrielle E. Roesch-Mcnally

Department of Agronomy and Horticulture: Faculty Publications

Cover crops as a conservation practice continue to receive attention from farmers, researchers, media, and policy makers, given their ability to effectively reduce water pollution and improve soil quality. Recent estimates of cover crop use across the midwestern Corn Belt, as well as the United States, demonstrate large acreage increases over the last number of years. The annual Sustainable Agriculture Research and Education–Conservation Technology Information Center (SARE– CTIC) survey found that nationally cover crop acreage doubled from 2011 to 2016, based on farmers self-reporting cover crop planting (CTIC 2016). However, the total cover crop acreage based on 2012 Census of …

Genotyping-By-Sequencing Derived High-Density Linkage Map And Its Application To Qtl Mapping Of Flag Leaf Traits In Bread Wheat, Waseem Hussain, P. Stephen Baenziger, Vikas Belamkar, Mary J. Guttieri, Jorge P. Venegas, Amanda Easterly, Ahmed Sallam, Jesse Poland

Department of Agronomy and Horticulture: Faculty Publications

Winter wheat parents ‘Harry’ (drought tolerant) and ‘Wesley’ (drought susceptible) were used to develop a recombinant inbred population with future goals of identifying genomic regions associated with drought tolerance. To precisely map genomic regions, high-density linkage maps are a prerequisite. In this study genotyping-by-sequencing (GBS) was used to construct the high-density linkage map. The map contained 3,641 markers distributed on 21 chromosomes and spanned 1,959 cM with an average distance of 1.8 cM between markers. The constructed linkage map revealed strong collinearity in marker order across 21 chromosomes with POPSEQ-v2.0, which was based on a high-density linkage map. The reliability …

Genomic-Enabled Prediction Accuracies Increased By Modeling Genotype × Environment Interaction In Durum Wheat, Sivakumar Sukumaran, Diego Jarquin, José Crossa, Matthew Reynolds

Department of Agronomy and Horticulture: Faculty Publications

Genomic prediction studies incorporating genotype × environment (G×E) interaction effects are limited in durum wheat. We tested the genomic-enabled prediction accuracy (PA) of Genomic Best Linear Unbiased Predictor (GBLUP) models—six non-G × E and three G × E models—on three basic cross-validation (CV) schemes— in predicting incomplete field trials (CV2), new lines (CV1), and lines in untested environments (CV0)— in a durum wheat panel grown under yield potential, drought stress, and heat stress conditions. For CV0, three scenarios were considered: (i) leave-one environment out (CV0-Env); (ii) leave one site out (CV0- Site); and (iii) leave 1 yr out (CV0-Year). The …

Validation Of Qtl Mapping And Transcriptome Profiling For Identification Of Candidate Genes Associated With Nitrogen Stress Tolerance In Sorghum, Malleswari Gelli, Anji Reddy Konda, Kan Liu, Chi Zhang, Thomas E. Clemente, David R. Holding, Ismail M. Dweikat

Department of Agronomy and Horticulture: Faculty Publications

Background: Quantitative trait loci (QTLs) detected in one mapping population may not be detected in other mapping populations at all the time. Therefore, before being used for marker assisted breeding, QTLs need to be validated in different environments and/or genetic backgrounds to rule out statistical anomalies. In this regard, we mapped the QTLs controlling various agronomic traits in a recombinant inbred line (RIL) population in response to Nitrogen (N) stress and validated these with the reported QTLs in our earlier study to find the stable and consistent QTLs across populations. Also, with Illumina RNA-sequencing we checked the differential expression of …

Evaluation Of Jules-Crop Performance Against Site Observations Of Irrigated Maize From Mead, Nebraska, Karina Williams, Jemma Gornall, Anna Harper, Andy Wiltshire, Debbie Hemming, Tristan Quaife, Tim Arkebauer, David Scoby

Department of Agronomy and Horticulture: Faculty Publications

The JULES-crop model (Osborne et al., 2015) is a parametrisation of crops within the Joint UK Land Environment Simulator (JULES), which aims to simulate both the impact of weather and climate on crop productivity and the impact of croplands on weather and climate. In this evaluation paper, observations of maize at three FLUXNET sites in Nebraska (US-Ne1, US-Ne2 and US-Ne3) are used to test model assumptions and make appropriate input parameter choices. JULES runs are performed for the irrigated sites (US-Ne1 and US-Ne2) both with the crop model switched off (prescribing leaf area index (LAI) and canopy height) and with …

Science In The Supply Chain: Collaboration Opportunities For Advancing Sustainable Agriculture In The United States, Allison M. Thomson, Stewart Ramsey, Ed Barnes, Bruno Basso, Marlen Eve, Sasha Gennet, Patricio Grassini, Brandon Kliethermes, Marty Matlock, Eileen Mcclellen, Ed Spevak, Clifford S. Snyder, Mark D. Tomer, Chris Van Kessel, Tristram West, Grant Wick

Department of Agronomy and Horticulture: Faculty Publications

Consumers and corporations are increasingly interested in understanding the sustainability of agricultural supply chains and reducing the environmental impacts of food, fiber, feed, and fuel production. This emerging need to quantify environmental impacts from agricultural production creates an opportunity for collaboration with the scientific community. Without such collaboration, sustainability efforts risk failure by adopting unrealistic goals or misguided approaches. This commentary explores the role of science in Field to Market, a nonprofit organization developing a sustainability program for US commodity crops, and highlights opportunities to address emerging science challenges. We evaluate changes over the past 35 years in key environmental …

Genetic Characterization Of The Soybean Nested Association Mapping Population, Qijian Song, Long Yan, Charles Quigley, Brandon D. Jordan, Edward Fickus, Steve Schroeder, Bao-Hua Song, Yong-Qiang Charles An, David Hyten, Randall L. Nelson, Katy Rainey, William D. Beavis, Jim Specht, Brian Diers, Perry Cregan

Department of Agronomy and Horticulture: Faculty Publications

A set of nested association mapping (NAM) families was developed by crossing 40 diverse soybean [Glycine max (L.) Merr.] genotypes to the common cultivar. The 41 parents were deeply sequenced for SNP discovery. Based on the polymorphism of the single-nucleotide polymorphisms (SNPs) and other selection criteria, a set of SNPs was selected to be included in the SoyNAM6K BeadChip for genotyping the parents and 5600 RILs from the 40 families. Analysis of the SNP profiles of the RILs showed a low average recombination rate. We constructed genetic linkage maps for each family and a composite linkage map based on …

Editorial: Genomic Approaches For Improvement Of Understudied Grasses, Keenan Amundsen, Gautam Sarath, Teresa Donze-Reiner

Department of Agronomy and Horticulture: Faculty Publications

Grasses are diverse, spanning native prairies to high-yielding grain cropping systems. They are valued for their beauty and useful for soil stabilization, pollution mitigation, biofuel production, nutritional value, and forage quality; grasses encompass the most important grain crops in the world. There are thousands of distinct grass species and many have promiscuous hybridization patterns, blurring species boundaries. Resources for advancing the science and knowledgebase of individual grass species or their unique characteristics varies, often proportional to their perceived value to society. For many grasses, limited genetic information hinders research progress. Presented in this research topic is a brief snapshot of …

Expression Of The Maize Dof1 Transcription Factor In Wheat And Sorghum, Pamela A. Pena, Truyen Quach, Shirley Sato, Zhengxiang Ge, Natalya Nersesian, Taity Changa, Ismail M. Dweikat, Madhavan Soundararajan, Tom E. Clemente

Department of Agronomy and Horticulture: Faculty Publications

Nitrogen is essential for plant growth and development. Improving the ability of plants to acquire and assimilate nitrogen more efficiently is a key agronomic parameter that will augment sustainability in agriculture. A transcription factor approach was pursued to address improvement of nitrogen use efficiency in two major commodity crops. To this end, the Zea mays Dof1 (ZmDof1) transcription factor was expressed in both wheat (Triticum aestivum) and sorghum (Sorghum bicolor) either constitutively, UBI4 promoter from sugarcane, or in a tissue specific fashion via the maize rbcS1 promoter. The primary transcription activation target of ZmDof1 …

Can Sub-Saharan Africa Feed Itself?, Martin K. Van Ittersum, Lenny G. J. Van Bussel, Joost Wolf, Patricio Grassini, Justin Van Wart, Nicolas Guilpart, Lieven Claessens, Hugo De Groot, Keith Wiebe, Daniel Mason-D'Croz, Haishun Yang, Hendrik Boogard, Pepijn A. J. Van Oort, Marloes P. Van Loon, Kazuki Saito, Ochieng Adimo, Samuel Adjei-Nsiah, Alhassane Agali, Abdullahi Bala, Regis Chikowo, Kayuki Kaizzi, Mamoutou Kouressy, Joachim H. J. R. Makoi, Korodjouma Ouattara, Kindie Tesfaye, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

Although global food demand is expected to increase 60% by 2050 compared with 2005/2007, the rise will be much greater in sub- Saharan Africa (SSA). Indeed, SSA is the region at greatest food security risk because by 2050 its population will increase 2.5-fold and demand for cereals approximately triple, whereas current levels of cereal consumption already depend on substantial imports. At issue is whether SSA can meet this vast increase in cereal demand without greater reliance on cereal imports or major expansion of agricultural area and associated biodiversity loss and greenhouse gas emissions. Recent studies indicate that the global increase …

Can Functional Traits Predict Plant Community Response To Global Change?, Sarah Kimball, Jennifer L. Funk, Marko J. Spasojevic, Katharine N. Suding, Scot Parker, Michael K. Goulden

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

One primary goal at the intersection of community ecology and global change biology is to identify functional traits that are useful for predicting plant community response to global change. We used observations of community composition from a long-term field experiment in two adjacent plant communities (grassland and coastal sage shrub) to investigate how nine key plant functional traits were related to altered water and nitrogen availability following fire. We asked whether the functional responses of species found in more than one community type were context dependent and whether community-weighted mean and functional diversity were significantly altered by water and nitrogen …

Salvinia Molesta: An Assessment Of The Effects And Methods Of Eradication, Arti Lal

Master's Projects and Capstones

Salvinia molesta is an invasive aquatic fern. It is now the second worse aquatic invader in the world. Since the 1930s, it has invaded most tropical and some temperate countries. S. molesta plants grow vegetatively and can increase in size rapidly. S. molesta can form thick mats of up to 1-meter-thick. There are a number of ways these thick mats negatively affect the environment: 1) reduce light to benthic organisms, 2) reduce oxygen in the water column for other organisms, 3) accumulate as organic matter at the bottom of the water column, 4) decrease nutrients for other organisms, and 5) …

Effect Of Smooth Bromegrass Management On Grazing Cattle Dung Decomposition, Co2 Flux, And Soil Nutrient Movement, Bradley D. Schick

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

Rapid nutrient cycling improves forage quality and livestock production in pastures. Interseeding legumes may be a strategy to enhance N cycling, but effects of dung excreted from cattle grazing pastures with legumes on dung decomposition rates and soil N cycling have not been studied. Our objective was to evaluate how dung excreted from cattle grazing legume-interseeded, N-fertilized, and unfertilized smooth bromegrass (Bromus inermis Leyss.) pastures affects dung chemical composition, dry matter decomposition, CO­₂ flux, and N availability in soil. Freshly deposited dung from yearling steers grazing legume-interseeded, N-fertilized, and unfertilized pastures was collected and placed as pats in …

Mechanism Of Resistance, Gene Flow, And Integrated Management Of Ragweeds (Ambrosia) In Nebraska, Zahoor Ahmad Ganie

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

Common ragweed (Ambrosia artemisiifolia L.) and giant ragweed (Ambrosia trifida L.) are native annual broadleaf weeds in the United States found in diverse agroecosystems, roadsides, and wastelands. They are economically important weed species in the Midwest and sources of pollen allergies. Confirmation of glyphosate-resistant (GR) common and giant ragweed in Nebraska justified the need to determine the mechanism of resistance, dispersal of resistance genes via pollen, and to develop an integrated management program. The objectives of this research were to: 1) determine the mechanism of glyphosate resistance in a common ragweed biotype from Nebraska; 2) evaluate the effect …

Modeling Long-Term Corn Yield Response To Nitrogen Rate And Crop Rotation, Laila A. Puntel, John E. Sawyer, Daniel W. Barker, Ranae Dietzel, Hanna Poffenbarger, Michael J. Castellano, Kenneth J. Moore, Peter J. Thorburn, Sotirios V. Archontoulis

Department of Agronomy and Horticulture: Faculty Publications

Improved prediction of optimal N fertilizer rates for corn (Zea mays L.) can reduce N losses and increase profits. We tested the ability of the Agricultural Production Systems sIMulator (APSIM) to simulate corn and soybean (Glycine max L.) yields, the economic optimum N rate (EONR) using a 16-year field-experiment dataset from central Iowa, USA that included two crop sequences (continuous corn and soybean-corn) and five N fertilizer rates (0, 67, 134, 201, and 268 kg N ha^-1) applied to corn. Our objectives were to: (a) quantify model prediction accuracy before and after calibration, and report calibration steps; (b) …

Characterization And Development Mechanism Of Apios Americana Tuber Starch, Hanyu Yangchen, Vikas Belamkar, Steven B. Cannon, Jay-Lin Jane

Department of Agronomy and Horticulture: Faculty Publications

Apios americana is a wild legume-bearing plant with edible tubers. Domestication of Apios is in progress because of the superior nutritional value and health benefits of the tuber. Objectives of this study were to: (1) characterize physicochemical properties of the Apios tuber starch; and (2) understand differences in starch structures and properties between the mother (seed) and child (progeny) tubers and the mechanism of starch development. Granules of the Apios tuber starch displayed ellipsoidal, rod, or kidney shape with diameter ranges of 1–30 m. The mother tuber starches displayed greater percentage crystallinity, larger gelatinization enthalpy-changes, longer branch-chain lengths of amylopectin, …