Characterizing Water and Nitrogen Stress in Corn Using Remote Sensing

Abstract

Interactions between water and N may impact remote-sensingbased N recommendations. The objectives of this study were to determine the influence of water and N stress on reflectance from a corn (Zea mays L.) crop, and to evaluate the impacts of implementing a remote-sensing-based model on N recommendations. A replicated N and water treatment factorial experiment was conducted in 2002, 2003, and 2004. Yield losses due to water (YLWS) and N (YLNS) stress were determined using the 13 C discrimination (D) approach. Reflectance data (400-1800 nm) collected at three growth stages (V8-V9, V11-VT, and R1-R2) were used to calculate six different remote sensing indices (normalized difference vegetation index [NDVI], green normalized vegetation index, normalized difference water index [NDWI], N reflectance index, and chorophyll green and red edge indices). At the V8-V9 growth stage, increasing the N rate from 0 to 112 kg N ha 21 decreased reflectance in the blue (485 nm), green (586 nm), and red (661 nm) bands. Nitrogen had an opposite effect in the near-infrared (NIR, 840 nm) band. At the V11-VT growth stage, reflectance in the blue, green, and red bands were lower in fertilized than unfertilized treatments. At the R1-R2 growth stage, YLWS was highly correlated (r 5 0.58, P 5 0.01) with red reflectance and NDVI (r 5 20.61, P 5 0.01), while YLNS was correlated with all of the indices except NDVI. A remote sensing model based on YLNS was more accurate at predicting N requirements than models based on yield or yield plus YLWS. These results were attributed to N and water having an additive effect on yield, and similar optimum N rates (100-120 kg N ha 21 ) for both moisture regimes.

Corn (<i>Zea Mays</i> L.) Plant Characteristics and Grain Yield Response to N Fertilization Programs in No-Tillage System

“…Increasing N application increased N content and chlorophyll content in corn (Pandey et al, 2000;Rambo et al, 2010). Clay et al (2006) observed that increasing the N rate from 0-112 kg N ha -1 decreased reflectance in the red (661 nm) bands at V8-V9 corn growth stage. Nitrogen stress reduced the production of chlorophyll that is involved in the photosynthesis.…”

Winter Oilseed-Rape Yield Estimates from Hyperspectral Radiometer Measurements

“…Spectral reflectance measurements can be used to monitor plant conditions (Gibbons & Freudenberger 2006, Ji-Hua & Bing-Fang 2008, estimate plant nutrient status (Nguyen & Byun-Woo 2006, Zhao et al 2005, detect abiotic and biotic stresses (Clay et al 2006, Gröll et al 2007, estimate plant growth rate (Beck et al 2007) and forecast crop yields (Galvao et al 2009, Li et al 2007. In order to make better use of spectral data, the vegetation indices are calculated using crop reflectance at differing wavelengths.…”

Spectral Remote Sensing of the Responses of Soybean Plants to Environmental Stresses

“…In stressed vegetation, leaf chlorophyll content decreases, thereby changing the proportion of lightabsorbing pigments, leading to a reduction in the overall absorption of light (Zarco-Tejada et al, 2000;Clay et al, 2006;Gang et al, 2010). These changes affect the spectral reflectance signatures of plants through a reduction in green reflection and an increase in red and blue reflections, resulting in changes in the normal spectral reflectance patterns of plants (ZarcoTejada et al, 2000;Campbell et al, 2007).…”