Agronomy and Crop Sciences Commons^™

The Last Continuous Grasslands On Earth: Identification And Conservation Importance, Rheinhardt Scholtz, Dirac L. Twidwell Jr

Department of Agronomy and Horticulture: Faculty Publications

Grasslands are the most threatened and least protected biome. Yet, no study has been conducted to identify the last remaining continuous grasslands on Earth. Here, we used World Wildlife Fund (WWF) and International Union for Conservation of Nature (IUCN) classifications to measure the degree of intactness remaining for the world's grassland ecoregions. This analysis revealed three findings of critical conservation importance. First, only a few large, intact grasslands remain. Second, every continent with a grassland ecoregion considered in this study contains at least one relatively intact grassland ecoregion. Third, the largest remaining continuous grasslands identified in this analysis have persisted …

Modeling The Evolution Of Herbicide Resistance In Weed Species With A Complex Life Cycle, K. Harrison Holmes, John L. Lindquist, Richard Rebarber, Rodrigo Werle, Melinda K. Yerka, Brigitte Tenhumberg

Brigitte Tenhumberg Papers

A growing number of weed species have evolved resistance to herbicides in recent years, which causes an immense financial burden to farmers. An increasingly popular method of weed control is the adoption of crops that are resistant to specific herbicides, which allows farmers to apply the herbicide during the growing season without harming the crop. If such crops are planted in the presence of closely related weed species, it is possible that resistance genes could transfer from the crop species to feral populations of the wild species via gene flow and become stably introgressed under ongoing selective pressure by the …

Ecological Intensification With Soil Health Practices Demonstrates Positive Impacts On Multiple Soil Properties: A Large-Scale Farmer-Led Experiment, Fernanda Souza Krupek, Daren D. Redfearn, Kent M. Eskridge, Andrea Basche

Department of Agronomy and Horticulture: Faculty Publications

Improving soil health is critical to reversing trends of soil degradation and is of increasing interest to a range of stakeholders including policymakers, agricultural industry leaders, food companies, and farmers. Crop and soil management practices focused on ecological functions can be effective in restoring fundamental biological, chemical and physical soil properties. The call for ecological intensification of agricultural systems has the potential to improve soil health and input-use efficiency. In this study, we developed a framework to classify spatial and temporal ecological intensification with soil health practices: tillage, crop rotation, cover crop, organic amendment, and crop-livestock integration. We applied this …

A Non-Destructive Approach For Measuring Rice Panicle-Level Photosynthetic Responses Using 3d-Image Reconstruction, Jaspinder Singh Dharni, Balpreet Kaur Dhatt, Puneet Paul, Tian Gao, Tala Awada, Paul Staswick, Jason Hupp, Hongfeng Yu, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Our understanding of the physiological response of rice inflorescence (panicle) to environmental stresses is limited by the challenge of accurately determining panicle photosynthetic parameters and their impact on grain yield. This is primarily due to lack of a suitable gas exchange methodology for panicles, as well as non-destructive methods to accurately determine panicle surface area. To address these challenges, we have developed a custom panicle gas exchange cylinder compatible with the LiCor 6800 Infra-red Gas Analyzer. Accurate surface area measurements were determined with a 3D panicle imaging platform to normalize the panicle-level photosynthetic measurements. We observed differential responses in both …

Evaluation Of Uav-Derived Multimodal Remote Sensing Data For Biomass Prediction And Drought Tolerance Assessment In Bioenergy Sorghum, Jiating Li, Daniel P. Schachtman, Cody F. Creech, Lin Wang, Yufeng Ge, Yeyin Shi

Department of Agronomy and Horticulture: Faculty Publications

Screening for drought tolerance is critical to ensure high biomass production of bioenergy sorghum in arid or semi-arid environments. The bottleneck in drought tolerance selection is the challenge of accurately predicting biomass for a large number of genotypes. Although biomass prediction by low-altitude remote sensing has been widely investigated on various crops, the performance of the predictions are not consistent, especially when applied in a breeding context with hundreds of genotypes. In some cases, biomass prediction of a large group of genotypes benefited from multimodal remote sensing data; while in other cases, the benefits were not obvious. In this study, …

A Phytobacterial Tir Domain Effector Manipulates Nad+ To Promote Virulence, Samuel Eastman, Thomas Smith, Mark A. Zaydman, Panya Kim, Samuel Martinez, Neha Damaraju, Aaron Diantonio, Jeffrey Milbrandt, Thomas Clemente, James R. Alfano, Ming Guo

Department of Agronomy and Horticulture: Faculty Publications

The Pseudomonas syringae DC3000 type III effector HopAM1 suppresses plant immunity and contains a Toll/interleukin-1 receptor (TIR) domain homologous to immunity-related TIR domains of plant nucleotide-binding leucine-rich repeat receptors that hydrolyze nicotinamide adenine dinucleotide (NAD+) and activate immunity. In vitro and in vivo assays were conducted to determine if HopAM1 hydrolyzes NAD+ and if the activity is essential for HopAM1’s suppression of plant immunity and contribution to virulence. HPLC and LC-MS were utilized to analyze metabolites produced from NAD+ by HopAM1 in vitro and in both yeast and plants. Agrobacterium-mediated transient expression and in planta inoculation assays were performed to …

Predicting Munsell Color For Turfgrass Leaves, William L. Berndt, Roch E. Gaussoin

Department of Agronomy and Horticulture: Faculty Publications

Linking turfgrass color to hue, value, chroma (H V/C) in the Munsell Plant Tissue Color Book is a visual comparison process for specifying and communicating plant color. If subjectivity of visual comparison can be mitigated, then accuracy of color matching may be improved. Research was conducted to develop an algorithm predicting H V/C from CIE-xyY color (xyY) in digital images of leaves of four turfgrasses. First, value-chroma (V/C) arrays for Munsell hue groups 5Y, 2.5GY, 5GY, 7.5GY, 10GY, and 2.5G were converted to xyY. Next, chromaticity (xy) plots from each array were fitted with …

Monitoring Environmental Policy Process: Indicators To Evaluate Performance, Stella Namanji, Charles A. Francis, Charles Ssekyewa, Geir Hofgaard Lieblein

Department of Agronomy and Horticulture: Faculty Publications

The complexity of environmental policy development was examined in relation to sustainability, holistic and systems-thinking perspectives. We studied potential application of systems principles of coordination, representation, collaboration, participation and teamwork to improve policy effectiveness at formulation, communication, implementation, and operationalisation of the environment policy in Uganda. The research unveiled the ineffectiveness of the Uganda National Environment Management Policy. We applied systems theory to develop a mechanism for monitoring effectiveness of environmental policies at national level, with the goal to identify key monitoring indicators. We used the soft systems methodology to identify occurring environmental problems causing forest loss. Results suggest that …

Charles A. Francis, Abstracts And Publications [1969--2022], December 2022, Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Contents

I. Journal articles (218), p.1

II. Book reviews (60), p. 18

III. Published abstracts (213), p. 23

IV. Books (23), p. 40

V. Chapters in books (81), p. 42

VI. Symposium or workshop proceedings (127), p. 50

VII. Symposia or extension publications edited (31), p. 62

VIII. Miscellaneous (522), p. 65

Biochar: Properties And Potential Benefits For Agricultural Soil In Rwanda, Andromede Uwase

Honors Theses

Physical and chemical soil degradation is becoming a major challenge for agricultural productivity in Rwanda, which is the most important part of the country’s economy. The wide spreading soil degradation in Rwanda is mainly a result of naturally poor soils coupled with unsustainable soil management leading to, for example, accelerated soil erosion, acidification, nutrient loss, compaction, and to decreasing yields. Biochar, as an end product of pyrolysis of biomass in the absence of oxygen, has been proposed as a soil amendment in remediation strategies because of its positive effects on soil productivity relevant parameters such as soil pH, structure, nutrient …

Characterization Of Salt And Drought Tolerance In Sunflower (Helianthus Annuus L.), Sevgi Saylak

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

Consequent to the increasing world population, food sources are needed to be increased to meet the nutritional needs. However, due to natural processes and agricultural activities, the most destructive environmental factors that limit crop production, soil salinity, and drought-exposed areas are growing. As one of the major oilseed crops, sunflower (Helianthus annuus L.), is considered to be moderately tolerant to salt and drought. Although it can grow in arid to semi-arid regions, increasing salinity and drought might adversely affect sunflower production. This study aimed to investigate several sunflower germplasms' morphological responses to salt and drought stresses. For this purpose, …

A New Perspective When Examining Maize Fertilizer Nitrogen Use Efficiency, Incrementally, Newell R. Kitchen, Curtis J. Ransom, James S. Schepers, Jerry L. Hatfield, Raymond Massey, Scott T. Drummond

Department of Agronomy and Horticulture: Faculty Publications

For maize (Zea mays L.), nitrogen (N) fertilizer use is often summarized from field to global scales using average N use efficiency (NUE). But expressing NUE as averages is misleading because grain increase to added N diminishes near optimal yield. Thus, environmental risks increase as economic benefits decrease. Here, we use empirical datasets obtained in North America of maize grain yield response to N fertilizer (n = 189) to create and interpret incremental NUE (iNUE), or the change in NUE with change in N fertilization. We show for those last units of N applied to reach economic optimal N …

First Plant Cell Atlas Symposium Report, Selena L. Rice, Elena Lazarus, Christopher Anderton, Kenneth Birnbaum, Jenniofer Brophy, Benjamin Cole, Diane Dickel, David Ehrhardt, Noah Fahlgren, Margaret Frank, Elizabeth Haswell, Shao-Shan Carol Huang, Samuel Leiboff, Marc Libault, Marisa S. Otegui, Nicholas Provart, R. Glen Uhrig, Seung Y. Rhee, The Plant Cell Atlas Consortium

Department of Agronomy and Horticulture: Faculty Publications

The Plant Cell Atlas (PCA) community hosted a virtual symposium on December 9 and 10, 2021 on single cell and spatial omics technologies. The conference gathered almost 500 academic, industry, and government leaders to identify the needs and directions of the PCA community and to explore how establishing a data synthesis center would address these needs and accelerate progress. This report details the presentations and discussions focused on the possibility of a data synthesis center for a PCA and the expected impacts of such a center on advancing science and technology globally. Community discussions focused on topics such as data …

Inactivation Of The Entire Arabidopsis Group Ii Gh3s Confers Tolerance To Salinity And Water Deficit, Rubén Casanova-Sáez, Eduardo Mateo-Bonmatí, Jan Šimura, Aleš Pěnčík, Ondřej Novák, Paul Staswick, Karin Ljung

Department of Agronomy and Horticulture: Faculty Publications

Indole-3-acetic acid (IAA) controls a plethora of developmental processes. Thus, regulation of its concentration is of great relevance for plant performance. Cellular IAA concentration depends on its transport, biosynthesis and the various pathways for IAA inactivation, including oxidation and conjugation.

Group II members of the GRETCHEN HAGEN 3 (GH3) gene family code for acyl acid amido synthetases catalysing the conjugation of IAA to amino acids. However, the high degree of functional redundancy among them has hampered thorough analysis of their roles in plant development.

In this work, we generated an Arabidopsis gh3.1,2,3,4,5,6,9,17 (gh3oct) mutant to knock out the group II …

Identification Of Beneficial And Detrimental Bacteria Impacting Sorghum Responses To Drought Using Multi-Scale And Multisystem Microbiome Comparisons, Mingsheng Qi, Jeffrey C. Berry, Kira W. Veley, Lily O'Connor, Omri M. Finkel, Isai Salas-González, Molly Kuhs, Julietta Jupe, Emily Holcomb, Tijana Glavina Del Rio, Cody Creech, Peng Liu, Susannah G. Tringe, Jeffery L. Dangl, Daniel P. Schachtman, Rebecca S. Bart

Department of Agronomy and Horticulture: Faculty Publications

Drought is a major abiotic stress limiting agricultural productivity. Previous field-level experiments have demonstrated that drought decreases microbiome diversity in the root and rhizosphere. How these changes ultimately affect plant health remains elusive. Toward this end, we combined reductionist, transitional and ecological approaches, applied to the staple cereal crop sorghum to identify key root-associated microbes that robustly affect drought-stressed plant phenotypes. Fifty-three Arabidopsis-associated bacteria were applied to sorghum seeds and their effect on root growth was monitored. Two Arthrobacter strains caused root growth inhibition (RGI) in Arabidopsis and sorghum. In the context of synthetic communities, Variovorax strains were able to …

Root Exudates Impact Plant Performance Under Abiotic Stress, Yen Ning Chai, Daniel P. Schachtman

Department of Agronomy and Horticulture: Faculty Publications

Plant root exudates serve pivotal roles in supporting plant development and interactions with the physicochemical and biological factors in the rhizosphere. Under stress conditions, root exudation is involved in enhancing plant resource-use efficiency and facilitating the crosstalk between plant and soil microbes to ameliorate stress. Although there are a large number of root exudates that remain to be characterized, recent technological advancements have allowed for the function of many exudate compounds to be elucidated. In this review, we discuss current knowledge about the key root exudates that modulate plant resource-use efficiency under various abiotic stresses including drought, aluminum toxicity, phosphorus, …

Regenerating Agroecosystems By Overcoming Human Exceptionalism In Designing For Increased Equity Of Benefits From Ecoservices, Ali Loker, Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Our commentary explores three critical issues related to ecosystem services. First is how ecoservices are currently designed and implemented primarily for human benefit without concern for how these impact other species. We conclude that awareness of this imbalance is the first step toward meaningful change. Second we observe that human exceptionalism guides most decisions, and ask whether we can overcome this mind-set to embrace ecoregeneration and design of resilient and mutually beneficial agroecosystems. Our attitude toward the challenge and moving toward greater humility about human roles that guide management decisions in the ecosystem is a requisite for change. Third we …

Field Validation Of A Farmer Supplied Data Approach To Close Soybean Yield Gaps In The Us North Central Region, José F. Andrade, Spyridon Mourtzinis, Juan I. Rattalino Edreira, Shawn P. Conley, John Gaska, Herman J. Kandel, Laura E. Lindsey, Seth Naeve, Scott Nelson, Maninder P. Singhi, Laura J. Thompson, James E. Specht, Patricio Grassini

Department of Agronomy and Horticulture: Faculty Publications

CONTEXT: Producer-reported data can be used to identify suites of management practices that lead to higher yield and profit. However, a rigorous validation of the approach in relation to its potential impact on farmer yield and profit is lacking.

OBJECTIVE: This study aimed to validate a producer-data approach on its capability to guide on-farm evaluation of management practices with greatest potential for increasing producer yield and profit. We show proof of concept using soybean in the North Central US region as a case study.

METHODS: We used a combination of regression tree analysis and a spatial framework to determine practices …

Gaia Contributions To Agroecology By James Lovelock (1919-2022), Steve Gliessman, Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

In writing about the history of agroecology we too often ignore the valuable contributions of British scientist James Lovelock who recently died on his 103rd birthday. A prolific inventor and influential theorist, Lovelock is best known for the Gaia hypothesis first proposed during his innovative work in the 1960s with the United States National Aeronautics and Space Administration. He suggested that ‘the biosphere has a regulatory effect on the Earth’s environment that acts to sustain life’ as written in Gaia: A New Look at Life on Earth (Lovelock 1979). Lovelock further proposed that humans have strongly impacted the planet’s capacity …

Temporal Changes In The Nutrient Content Of Cattle Dung In The Nebraska Sandhills Ecosystem, Amanda Shine, Martha Mamo, Gandura O. Abagandura, Walter Schacht, Jerry Volesky

Department of Agronomy and Horticulture: Faculty Publications

Dung excreted by cattle composes a significant portion of the nutrient inputs in a grazed ecosystem and can have wide-ranging effects on soil properties and vegetation. However, little research has been conducted on the nutrient dynamics of excreted dung in situ that has not been disturbed prior to field sampling. In this study, we analyzed 294 dung pats (1–24 days old) collected from a Nebraska Sandhills meadow to determine water-extractable organic carbon (WEOC), water-extractable nitrogen (WEN), water-extractable phosphorus (WEP), and percent dry matter (DM) changes over time. In addition, we investigated if sample handling - frozen storage – and the …

4-Hydroxyphenylpyruvate Dioxygenase (Hppd)-Inhibiting Herbicides: Past, Present, And Future, Amit J. Jhala, Vipan Kumar, Ramawatar Yadav, Prashant Jha, Mithila Jugulam5, Martin M. Williams Ii, Nicholas E. Hausman, Franck E. Dayan, Paul M. Burton, Richard P. Dale, Jason K. Norsworthy

Department of Agronomy and Horticulture: Faculty Publications

The 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicides are primarily used for weed control in corn, barley, oat, rice, sorghum, sugarcane, and wheat production fields in the United States. The objectives of this review were to summarize (1) the history of HPPD-inhibitor and their use in the United States, (2) HPPD-inhibitor resistant weeds, their mechanism of resistance, and management, (3) interaction of HPPD-inhibitor with other herbicides, and (4) the future of HPPD-inhibitor-resistant crops. As of 2022, three broadleaf weeds (Palmer amaranth, waterhemp, and wild radish) have evolved resistance to the HPPD-inhibitor. The predominance of metabolic resistance to HPPD-inhibitor was found in aforementioned three …

Predicting Munsell Color For Turfgrass Leaves, William L. Berndt, Roch E. Gaussoin

Department of Agronomy and Horticulture: Faculty Publications

Linking turfgrass color to hue, value, chroma (H V/C) in the Munsell Plant Tissue Color Book is a visual comparison process for specifying and communicating plant color. If subjectivity of visual comparison can be mitigated, then accuracy of color matching may be improved. Research was conducted to develop an algorithm predicting H V/C from CIE-xyY color (xyY) in digital images of leaves of four turfgrasses. First, value-chroma (V/C) arrays for Munsell hue groups 5Y, 2.5GY, 5GY, 7.5GY, 10GY, and 2.5G were converted to xyY. Next, chromaticity (xy) plots from each array were fitted with …

Limited Irrigation For Managing Declining Water Resources In The Us High Plains, Bijesh Maharjan, Gary Hergert, Saurav Das

Department of Agronomy and Horticulture: Faculty Publications

The US High Plains region has a semiarid climate receiving between 330 and 455 mm of rainfall annually. In the Nebraska Panhandle of the High Plains, 30-year average rainfall is 394 mm, and one-fourth of agriculture is under irrigation. In addition to concerns about water quality, there is a growing concern over water quantity for ground- and surface-water resources that producers use for irrigation. Wisely managing limited water resources for irrigation can help maintain crop productivity and profitability. Deficit irrigation research for 13 years (2005–2017) was conducted in the Nebraska Panhandle to study effects of limited irrigation on maize ( …