Physical Sciences and Mathematics Commons^™

Leveraging Image Analysis For High-Throughput Plant Phenotyping, Sruti Das Choudhury, Ashok Samal, Tala Awada

Papers in Natural Resources

The complex interaction between a genotype and its environment controls the biophysical properties of a plant, manifested in observable traits, i.e., plant’s phenome, which influences resources acquisition, performance, and yield. High-throughput automated image-based plant phenotyping refers to the sensing and quantifying plant traits non-destructively by analyzing images captured at regular intervals and with precision. While phenomic research has drawn significant attention in the last decade, extracting meaningful and reliable numerical phenotypes from plant images especially by considering its individual components, e.g., leaves, stem, fruit, and flower, remains a critical bottleneck to the translation of advances of phenotyping technology into genetic …

Gene Flow From Single And Stacked Herbicide-Resistant Rice (Oryza Sativa): Modeling Occurrence Of Multiple Herbicide-Resistant Weedy Rice, Joseph Dauer, Andrew Hulting, Dale Carlson, Luke Mankin, John Harden, Carol Mallory-Smith

Papers in Natural Resources

Background: Provisia™ rice (PV), a non-genetically engineered (GE) quizalofop-resistant rice, will provide growers with an additional option for weed management to use in conjunction with Clearfield® rice (CL) production. Modeling compared the impact of stacking resistance traits versus single traits in rice on introgression of the resistance trait to weedy rice (also called red rice). Common weed management practices were applied to 2-, 3- and 4-year crop rotations, and resistant and multiple-resistant weedy rice seeds, seedlings and mature plants were tracked for 15 years.

Results: Two-year crop rotations resulted in resistant weedy rice after 2 years with abundant populations (exceeding …

Temporal Variability In Aboveground Plant Biomass Decreases As Spatial Variability Increases, Devan Allen Mcgranahan, Torre J. Hovick, R. Dwayne Elmore, David M. Engle, Samuel D. Fuhlendorf, Stephen L. Winter, James R. Miller, Diane M. Debinski

Papers in Natural Resources

Ecological theory predicts that diversity decreases variability in ecosystem function. We predict that, at the landscape scale, spatial variability created by a mosaic of contrasting patches that differ in time since disturbance will decrease temporal variability in aboveground plant biomass. Using data from a multi-year study of seven grazed tallgrass prairie landscapes, each experimentally managed for one to eight patches, we show that increased spatial variability driven by spatially patchy fire and herbivory reduces temporal variability in aboveground plant biomass. This pattern is associated with statistical evidence for the portfolio effect and a positive relationship between temporal variability and functional …

Temporal Variability In Aboveground Plant Biomass Decreases As Spatial Variability Increases, Devan Allen Mcgranahan, Torre J. Hovick, R. Dwayne Elmore, David M. Engle, Samuel D. Fuhlendorf, Stephen L. Winter, James R. Miller, Diane M. Debinski

Papers in Natural Resources

Ecological theory predicts that diversity decreases variability in ecosystem function. We predict that, at the landscape scale, spatial variability created by a mosaic of contrasting patches that differ in time since disturbance will decrease temporal variability in aboveground plant biomass. Using data from a multi-year study of seven grazed tallgrass prairie landscapes, each experimentally managed for one to eight patches, we show that increased spatial variability driven by spatially patchy fire and herbivory reduces temporal variability in aboveground plant biomass. This pattern is associated with statistical evidence for the portfolio effect and a positive relationship between temporal variability and functional …

Seasonal Fires, Bison Grazing, And The Tallgrass Prairie Forb Arnoglossum Plantagineum Raf., Stephen L. Winter, Karen R. Hickman, Carla L. Goad, Samuel D. Fuhlendorf, Mark S. Gregory

Papers in Natural Resources

Fire and grazing can interact to affect the structure and composition of vegetation communities in a manner that may differ from the effects of fire or grazing that occurs in isolation of the other. In order to better understand the effects of a fire-grazing interaction at the level of an individual plant species, we studied the response of a perennial tallgrass prairie forb, Arnoglossum plantagineum Raf., to the interaction of spring and summer fires with grazing by bison (Bison bison L.). During one field season (2006), we collected data in areas that had been treated with summer fires while …

Modeling Gross Primary Production Of Irrigated And Rain-Fed Maize Using Modis Imagery And Co2 Flux Tower Data, Joshua L. Kalfas, Xiangming Xiao, Diana X. Vanegas, Shashi B. Verma, Andrew E. Suyker

Papers in Natural Resources

Abstract

Information on gross primary production (GPP) of maize croplands is needed for assessing and monitoring maize crop conditions and the carbon cycle. A number of studies have used the eddy covariance technique to measure net ecosystem exchange (NEE) of CO₂ between maize cropland fields and the atmosphere and partitioned NEE data to estimate seasonal dynamics and interannual variation of GPP in maize fields having various crop rotation systems and different water management practices. How to scale up in situ observations from flux tower sites to regional and global scales is a challenging task. In this study, the Vegetation …

Coupling Of Carbon Dioxide And Water Vapor Exchanges Of Irrigated And Rainfed Maize–Soybean Cropping Systems And Water Productivity, Andrew E. Suyker, Shashi B. Verma

Papers in Natural Resources

Continuous measurements of CO₂ and water vapor exchanges made in three cropping systems (irrigated continuous maize, irrigated maize–soybean rotation, and rainfed maize–soybean rotation) in eastern Nebraska, USA during 6 years are discussed. Close coupling between seasonal distributions of gross primary production (GPP) and evapotranspiration (ET) were observed in each growing season. Mean growing season totals of GPP in irrigated maize and soybean were 1738 ± 114 and 996 ± 69 g C m⁻², respectively (±standard deviation). Corresponding mean values of growing season ET totals were 545 ± 27 and 454 ± 23 mm, respectively. Irrigation affected GPP …

Ecophysiology Of Two Native Invasive Woody Species And Two Dominant Warm-Season Grasses In The Semiarid Grasslands Of The Nebraska Sandhills, Kathleen D. Eggemeyer, Tala Awada, David A. Wedin, F. Edwin Harvey, Xinhua Zhou

Papers in Natural Resources

Populations of Pinus ponderosa and Juniperus virginiana are expanding into semiarid Sandhills grasslands in Nebraska. To evaluate the physiological basis of their success, we measured the seasonal course of leaf gas exchange, plant water status, and carbon isotope discrimination in these two native trees and two native C₄ grasses (Schizachyrium scoparium and Panicum virgatum). Compared to the trees, grasses had higher net photosynthetic rates (A_net) and water use efficiency (WUE) and more negative predawn and midday water potentials (Ψ) in June and July. While leaf Ψ and rates of leaf gas exchange declined for all …

Comparison Of Modis And Avhrr 16-Day Normalized Difference Vegetation Index Composite Data, Kevin P. Gallo, Lei Ji, Brad Reed, John Dwyer, Jeffrey Eidenshink

Papers in Natural Resources

Normalized difference vegetation index (NDVI) data derived from visible and near-infrared data acquired by the MODIS and AVHRR sensors were compared over the same time periods and a variety of land cover classes within the conterminous USA. The relationship between the AVHRR derived NDVI values and those of future sensors is critical to continued long term monitoring of land surface properties. The results indicate that the 16-day composite values are quite similar over the 23 intervals of 2001 that were analyzed, and a linear relationship exists between the NDVI values from the two sensors. The composite AVHRR NDVI data were …

Remote Estimation Of Vegetation Fraction In Corn Canopies, D. Rundquist, Anatoly A. Gitelson, D. Derry, J. Ramirez, R. Stark, Galina P. Keydan

Papers in Natural Resources

The aim of the paper was to test two new techniques that make use of channels in the visible range of the spectrum only to estimate vegetation fraction in corn canopies. High spectral resolution radiometers were employed to measure spectral reflectance, and the information content of spectra was investigated. Radiances in spectral channels of MODIS and MERIS were used to calculate Visible Atmospherically Resistant Indices, VARI_green=(R_green- R_red)/(R_green+R_red-R_blue) and VARI₇₀₀=(R₇₀₀-1.7*R_red+0.7*R_blue)/(R₇₀₀+2.3*R_red-1.3*R_blue). The indices allowed for estimation …