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Removal Of Redox-Sensitive Rubisco Activase Does Not Alter Rubisco Regulation In Soybean, Christopher M. Harvey, Amanda P. Cavanagh, Sang Yeol Kim, David A. Wright, Ron G. Edquilang, Kayla S. Shreeves, Juan Alejandro Perdomo, Martin H. Spalding, Donald R. Ort, Carl J. Bernacchi, Steven C. Huber

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Rubisco activase (Rca) facilitates the catalytic repair of Rubisco, the CO2-fixing enzyme of photosynthesis, following periods of darkness, low to high light transitions or stress. Removal of the redox-regulated isoform of Rubisco activase, Rca-α, enhances photosynthetic induction in Arabidopsis and has been suggested as a strategy for the improvement of crops, which may experience frequent light transitions in the field; however, this has never been tested in a crop species. Therefore, we used RNAi to reduce the Rca-α content of soybean (Glycine max cv. Williams 82) below detectable levels and then characterized the growth, photosynthesis, and Rubisco activity of the …

Difference In Seasonal Peak Timing Of Soybean Far-Red Sif And Gpp Explained By Canopy Structure And Chlorophyll Content, Genghong Wu, Chongya Jiang, Hyungsuk Kimm, Sheng Wang, Carl Bernacchi, Caitlin E. Moore, Andy Suyker, Xi Yang, Troy Magney, Christian Frankenberg, Youngryel Ryu, Benjamin Dechant, Kaiyu Guan

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Recent advances in remotely sensed solar-induced chlorophyll fluorescence (SIF) have provided an exciting and promising opportunity for estimating gross primary production (GPP). Previous studies mainly focused on the linear correlation between SIF and GPP and the slope of the SIF-GPP relationship, both of which lack rigorous consideration of the seasonal trajectories of SIF and GPP. Here, we investigated the timing of seasonal peaks of far-red SIF and GPP in soybean fields by integrating tower data, satellite data, and process-based Soil Canopy Observation of Photosynthesis and Energy (SCOPE, v2.0) model simulations. We found inconsistency between the seasonal peak timing of far-red …

High-Throughput Characterization, Correlation, And Mapping Of Leaf Photosynthetic And Functional Traits In The Soybean (Glycine Max) Nested Association Mapping Population, Christopher M. Montes, Carolyn Fox, Álvaro Sanz-Sáez, Shawn P. Serbin, Etsushi Kumagai, Matheus D. Krause, Alencar Xavier, James E. Specht, William D. Beavis, Carl J. Bernacchi, Brian W. Diers, Elizabeth A. Ainsworth

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Photosynthesis is a key target to improve crop production in many species including soybean [Glycine max (L.) Merr.]. A challenge is that phenotyping photosynthetic traits by traditional approaches is slow and destructive. There is proof-of-concept for leaf hyperspectral reflectance as a rapid method to model photosynthetic traits. However, the crucial step of demonstrating that hyperspectral approaches can be used to advance understanding of the genetic architecture of photosynthetic traits is untested. To address this challenge, we used full-range (500-2,400 nm) leaf reflectance spectroscopy to build partial least squares regression models to estimate leaf traits, including the rate-limiting processes of photosynthesis, …

Weekly Survivorship Curves Of Soybean Aphid Biotypes 1 And 4 On Insecticidal Seed-Treated Soybean, Carlos J. Esquivel, Christopher M. Ranger, P. Larry Phelan, Erick J. Martinez, William H. Hendrix, Andrew P. Michel

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Thiamethoxam, an insecticide used in soybean seed treatments, effectively suppresses soybean aphids (Aphis glycines) Matsumura (Hemiptera: Aphididae) for a short time after planting. However, exactly when and how quickly soybean aphid populations could increase is unknown. Likewise, we lack data on virulent soybean aphid biotypes (that can overcome soybean resistance) when fed on seed-treated soybean. Determining the survival of soybean aphids over time on insecticidal seed-treated soybean is critical for improving soybean aphid management and may provide insights to manage aphid virulence to aphid resistant-soybean. In greenhouse and field experiments, aphid-susceptible soybean plants (with and without an insecticidal seed treatment) …

Impacts Of Elevated Co2 Concentration On The Productivity And Surface Energy Budget Of The Soybean And Maize Agroecosystem In The Midwest Usa, Tracy E. Twine, Jarod J. Bryant, Katherine T. Richter, Carl J. Bernacchi, Kelly D. Mcconnaughay, Sherri J. Morris, Andrew D. B. Leakey

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The physiological response of vegetation to increasing atmospheric carbon dioxide concentration ([CO₂]) modifies productivity and surface energy and water fluxes. Quantifying this response is required for assessments of future climate change. Many global climate models account for this response; however, significant uncertainty remains in model simulations of this vegetation response and its impacts. Data from in situ field experiments provide evidence that previous modeling studies may have overestimated the increase in productivity at elevated [CO₂], and the impact on large-scale water cycling is largely unknown. We parameterized the Agro-IBIS dynamic global vegetation model with observations from …

Morpho-Physiological Parameters Affecting Iron Deficiency Chlorosis In Soybean (Glycine Max L.), Marta W. Vasconcelos, Michael A. Grusak

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Background and aims Iron deficiency chlorosis (IDC) leads to severe leaf chlorosis, low photosynthetic rates, and yield reductions of several million metric tonnes each year. In order to devise breeding and genetic transformation programs that aim at generating high-yielding and IDC-tolerant soybean lines, it is necessary to better understand the mechanisms that enable tolerant plants to survive under Fe-limiting conditions.

Methods An in silico analysis in the USDA soybean collection allowed the identification of a set of novel efficient and inefficient soybean cultivars which can be used in future studies concerning IDC response. Plants were grown in iron deficient and …

The Influence Of Plants On Atmospheric Methane In An Agriculture-Dominated Landscape, Xin Zhang, Xuhui Lee, Timothy J. Griffis, John M. Baker, Matt D. Erickson, Ning Hu, Wei Xiao

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The primary objective of this study was to clarify the influence of crop plants on atmospheric methane (CH₄) in an agriculture-dominated landscape in the Upper Midwest of the United States. Measurements were carried out at two contrasting scales. At the plant scale, CH₄ fluxes from soybean and corn plants were measured with a laser-based plant chamber system. At the landscape scale, the land surface flux was estimated with a modified Bowen ratio technique using measurements made on a tall tower. The chamber data revealed a diurnal pattern for the plant CH₄ flux: it was positive (an …

Thirty-Year Tillage Effects On Crop Yield And Soil Fertility Indicators, Douglas Karlen, John L. Kovar, Cynthia A. Cambardella, Thomas S. Colvin

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Long-term studies are crucial for quantifying tillage effects on productivity and soil fertility. Moldboard plow, chisel plow, spring disk, ridge-tillage, and no-tillage systems were evaluated after 32 years of a corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation and 27 years of continuous corn in central Iowa, U.S.A. Productivity was quantified using yield, while soil fertility status was evaluated by collecting four, 5-cm diameter soil cores to a depth of 0.9 m from each treatment, dividing them into four depth increments (0–15-, 15–30-, 30–60-, and 60–90-cm), analyzing them for bulk density (BD), NO₃-N, …

Soil Quality Response To Long-Term Tillage And Crop Rotation Practices, Douglas Karlen, Cynthia A. Cambardella, John L. Kovar, Thomas S. Colvin

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Soil quality is influenced by inherent and anthropogenic factors. This study was conducted to provide multiple groups guidance on how to achieve and maintain improved soil quality/health. Our hypothesis was that tillage intensity was the primary anthropogenic factor degrading soil quality, and our objective was to prove that hypothesis through an intensive 2005 sampling of a central Iowa, USA field study. Chisel plow, disk tillage, moldboard plow, ridge-till and no-till treatments, used for 31 years in a twoyear, corn (Zea mays L.)/soybean [Glycine max (L.) Merr.] (C/S) rotation or for 26 years of continuous corn (CC) production, were …

Chapter 20 Rainfed Farming Systems In The Usa, Alan Franzluebbers, Jean L. Steiner, Doug Karlen, Tim Griffin, Jeremy Singer, Don Tanaka

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

This chapter describes characteristics of four major rainfed farming regions and systems in the USA: Great Plains wheat-sorghum-cattle; midwestern corn-soybean-hogs, southern cotton-peanut-poultry, and coastal diversified cropsdairy. Rainfed farming systems in the USA are highly productive, economically important, ecologically diverse and technologically driven. Management approaches to achieve resource efficiency and agricultural sustainability are described, including the use of improved genetic seed sources, crop rotations, appropriate fertiliser application techniques, conservation tillage and integrated crop-livestock production systems. Issues of increasing oil and fertiliser prices, sustainability of soil and water resources, and climate change are current challenges facing agriculture in the USA.

Crop Production Comparison With Spray, Lepa, And Subsurface Drip Irrigation In The Texas High Plains, Paul D. Colaizzi, Steven R. Evett, T. A. Howell, R. L. Baumhardt

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Irrigation application method may affect crop yield and water productivity. Crop production was compared for spray, LEPA drag sock, and subsurface drip irrigation (SDI) application methods in the Texas High Plains. Crops included three seasons of grain sorghum, one season of soybean, and four seasons of cotton. Irrigation treatments were 0, 25, 50, 75, and 100% of replacing full crop evapotranspiration, which was measured by neutron probe. For grain sorghum, SDI resulted in the largest grain yield and water use efficiency at the 25 and 50% irrigation treatments, followed by LEPA, but spray outperformed LEPA and SDI at the 75 …

Effects Of Atmospheric Co2 Enrichment On Crop Nutrient Dynamics Under No-Till Conditions, Stephen A. Prior, G. Brett Runion, Hugo H. Rogers, H. Allen Torbert

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Increasing atmospheric CO₂ concentration could increase crop productivity and alter crop nutrient dynamics. This study was conducted (3 yrs) with two crops ([Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench.]) grown under two CO₂ levels (ambient and twice ambient) using open top field chambers on a Blanton loamy sand under no-tillage. Macronutrient and micronutrient concentrations and contents were determined for grain, stover, and roots. Although elevated CO₂ tended to reduce nutrient concentrations, high CO₂ consistently increased nutrient content especially in grain tissue; this response pattern was more notable with macronutrients. The …

Composition Of Irrigation Water Salinity Affects Growth Characteristics And Uptake Of Selenium And Salt Ions By Soybean, D. Wang, C. M. Grieve, D. L. Suarez

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

A greenhouse study was conducted to determine the effects of irrigation waters differing in salt composition on growth characteristics, salt ion and selenium (Se) accumulation, and distribution in plant components of the soybean (Glycine max L. Merr.) cultivar “Manokin.” Plants were grown in sand cultures and irrigated with isoosmotic solutions containing (1) Cl⁻ as the dominant anion, or (2) a mixture of salts containing equal molar amounts of SO_^2-4 and Cl⁻. Six treatments of each salinity type were imposed. Electrical conductivities of the irrigation waters ranged from 2.1 to 13.0 dSm⁻¹. Selenium …