A5086598999- Remote Sensing in Agriculture
- Plant Water Relations and Carbon Dynamics
- Plant responses to elevated CO2
- Leaf Properties and Growth Measurement
- Urban Heat Island Mitigation
- Atmospheric and Environmental Gas Dynamics
- Greenhouse Technology and Climate Control
- Calibration and Measurement Techniques
- Remote Sensing and Land Use
- Climate variability and models
- Forest ecology and management
- Land Use and Ecosystem Services
- Horticultural and Viticultural Research
- Turfgrass Adaptation and Management
- Soil and Environmental Studies
- Soil and Unsaturated Flow
- Radiative Heat Transfer Studies
- Plant Pathogens and Fungal Diseases
- Soil Geostatistics and Mapping
- Crop Yield and Soil Fertility
- Tree-ring climate responses
- Climate change impacts on agriculture
- Cryospheric studies and observations
- Solar Radiation and Photovoltaics
- Atmospheric aerosols and clouds
University of Nebraska–Lincoln
2009-2024
Institute of Agriculture and Natural Resources
1995
Goddard Space Flight Center
1991-1992
Abstract Techniques that measure the N status of corn ( Zea mays L.) can aid in management decisions have economic and environmental implications. This study was conducted to identify reflected electromagnetic wavelengths most sensitive detecting deficiencies a canopy with possibility for use as tool. Reflected shortwave radiation measured from an irrigated response trial four hybrids five rates at 0, 40, 80, 120, 160 kg ha −1 1992 50, 100, 150, 200 1993. A portable spectroradiometer used...
Environmental stresses on plants are among the major limitations to crop productivity. Plants naturally equipped with a set of acclimatory mechanisms enabling them withstand without irreversible damage. Here, we overhauled approach non-invasive gauging response maize combined drought and high-light stresses. This was done leverage advantages recently developed framework based using reflected signal absorption coefficient modality. We document deployment two responses, one non-photochemical...
Land surface reflectance measurements were acquired during the First ISLSCP Field Experiment (FIFE) field campaigns using a variety of ground‐based and airborne spectral radiometers. To examine validity assumption that values by several different instruments teams interchangeable, radiation measurement converged on common site for 1 day fifth intensive campaign (IFC 5) in 1989. The compared near‐surface included two Spectron Engineering SE59Os, one helicopter‐mounted SE590, Barnes modular...
Abstract The fractional absorption of photosynthetically active radiation ( f PAR ) is frequently a key variable in models describing terrestrial ecosystem–atmosphere interactions, carbon uptake, growth and biogeochemistry. We present novel approach to the estimation fraction incident absorbed by photosynthetic components plant canopy Chl ). method uses micrometeorological measurements CO 2 flux estimate light response parameters from which structure deduced. Data two Ameriflux sites...
Leaves of the dominant grass species First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) site reflect and transmit radiation in a similar manner to other healthy green leaves. Visible reflectance factors (RFs) transmittance (TFs) were lower for older leaves than younger except during senescence, when RF TF values higher. Near‐infrared (NIR) increased decreased with leaf age, reverse occurring as underwent senescence. Leaf optical properties not...
Optical reflectance from leaf surfaces has been known for decades to increase with decreasing water content. Experimental results show this consistently in maize the visible (photosynthetically active radiation—PAR) and middle infrared (MIR) spectral regions, weaker correlation near (NIR) region. Changes chlorophyll concentration have shown be too small substantially contribute increasing during duration of these experiments. Therefore, responses deficit are perplexing since PAR region is...
Net CO 2 assimilation as a function of internal and stomatal conductance to water vapor were measured on blades the C 4 grasses Andropogon gerardii Vitman, Panicum virgatum L., Sorghastrum nutans (L.) Nash in northeast Kansas over two growing seasons determine comparative physiological responses these dominant tallgrass prairie environmental variables. The response dark respiration temperature net concentration absorbed quantum flux differed little among species. A. had lower potential...
Abstract Leaves have a major influence on canopy reflectance when they constitute the main spatial component in vegetative canopy. Near normal‐incidence, directional‐hemispherical and transmittance of situ individual leaves soybean ( Glycine max. , Merr.) corn Zea mays L.) were characterized as function wavelengths growth. Spectral properties measured seven wavebands with an integrating sphere prototype radiometer unit. Individual periodically monitored from emergence unfolding through 47 d...
Abstract Sun‐induced fluorescence (SIF) has been found to be strongly correlated with gross primary production (GPP) in a quasi‐linear pattern at the scales beyond leaves. However, causes of GPP:SIF relationship deviating from linear remain unclear. In current study conducted two maize sites Nebraska 2017 summer growing season, we investigated between GPP and SIF 760 nm (F ) temporal quantified contributions incoming photosynthetically active radiation (PAR ), fraction absorbed PAR (fPAR),...
Periodic upgrades of air temperature measurement systems in surface weather station networks cause data discontinuities. From a climatological viewpoint, it is necessary to evaluate the discontinuities when radiation shields are upgraded. This study was undertaken investigate effectiveness four common including Automated Surface Observing System (ASOS), Maximum–Minimum Temperature (MMTS), Gill, and Cotton Region Shelter (CRS) shields. The solar shielding for each shield under typical grass...
A procedure for determination of conifer needle spectral optical properties (transmittance, T/sub /spl lambda//; reflectance, R/sub lambda/=wavelength) was developed to support field measurements acquired in the Boreal Ecosystem-Atmosphere Study (BOREAS). This a revision protocol, C.S. Daughtry et al. (1989), which uses an indirect and labor-intensive step (involving painting needles) estimate inter-needle light transmittance gaps, or gap fraction (GF), each sample. The present authors...
Real‐time monitoring of crop vegetation fraction and identification development stages provides useful information for management. Using sensors at close range makes it possible to collect data with very high temporal resolution. This study used four‐band radiometers green, red, red edge, near infrared spectral bands daily maize ( Zea mays L.) soybean [ Glycine max (L.) Merr.] reflectance during the growing season in three fields over 3 yr. Two were continuous irrigated third was managed...
Ultraviolet‐B radiation (UV‐B, 280–320 nm) reaching the earth’s surface has deleterious effects on plants. The degree of susceptibility to UV‐B is dependent amount energy present in longer wavelengths ultraviolet‐A (UV‐A, 320–400 and photosynthetically active (PAR, 400–700 nm). This study was conducted quantify UV PAR light environment describe UV‐B/UV‐A UV‐B/PAR ratios above below developing vegetative canopies. Transmitted irradiant flux densities UV‐B, UV‐A, a alfalfa ( Medicago sativa...
Trellis or training systems influence many aspects of grapevine growth and production. This study investigated the effects four trellis styles (Geneva double curtain, high cordon, Smart-Dyson, vertical shoot positioned) on fruit-zone light environment, fruit chemical composition, yield 'Frontenac' grapevines (Vitis spp.) grown a fertile site near Crete, Nebraska over two growing seasons. Photosynthetically active radiation was measured above canopy within fruiting zone at berry set,...