Optical and fluorescence properties of corn leaves from different nitrogen regimes

Abstract

The important role of nitrogen (N) in limiting or enhancing vegetation productivity is relatively well understood, although the interaction of N with other environmental variables in natural and agricultural ecosystems needs more study. In 2001, a suite of optical, fluorescence, and biophysical measurements were collected on leaves of corn (Zea Mays L.) from field plots provided four N fertilizer application rates: 20%, 50%, 100% and 150% of optimal N levels. Two complementary sets of high-resolution (< 2 nm) optical spectra were acquired for both adaxial and abaxial leaf surfaces. The first was comprised of leaf optical properties (350-2500 nm) for reflectance, transmittance, and absorptance. The second was comprised of reflectance spectra (500-1000 nm) acquired with and without a long pass 665 nm filter to determine the fluorescence contribution to "apparent reflectance" in the 670-750 nm spectrum that includes the 685 and 740 nm chlorophyll fluorescence (ChlF) peaks. Two types of fluorescence measurements were also made on adaxial and abaxial surfaces: 1) fluorescence images in four 10 nm bands (blue, green, red, far-red) resulting from broadband irradiance excitation; and 2) emission spectra at 5 nm resolution produced by three excitation wavelengths (280, 380, and 532 nm). The strongest relationships between optical properties and foliar chemistry were obtained for a "red-edge" optical parameter versus C/N and chlorophyll b. Select optical indices and ChlF parameters were correlated. A significant contribution of steady-state ChlF to apparent reflectance was observed, averaging 10-25% at 685 nm and 2-6% at 740 nm over the range of N treatments. From all measurements assessing fluorescence, higher ChlF was measured from the abaxial leaf surfaces.Keywords: high spectral resolution reflectance and fluorescence, chlorophyll fluorescence, carbon/nitrogen ratio, chlorophyll b, red edge, nitrogen deficiency and excess.

Experimental Research of Reliability of Plant Stress State Detection by Laser-Induced Fluorescence Method

“…The results presented in Figures 2-6 are in agreement with those of other experimental researches [8,12] on plants under nitrogen stress and soil pollution using a fluorescence excitation source at the wavelength of 532 nm.…”

“…Fluorescence analysis is a widely used high-sensitivity method that is applied in many scientific and technical fields. A viable application of the technique is the analysis of plant state [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. External factors can cause plants stress and make their growth abnormal.…”

Integrating Solar Induced Fluorescence and the Photochemical Reflectance Index for Estimating Gross Primary Production in a Cornfield

“…NPQ and chlorophyll fluorescence emission are considered as direct indicators of photosynthetic activities and physiological stress when plants are under sub-optimal environmental conditions [28,53,59,80,[90][91][92][93] such as low water availability [81,[93][94][95], unfavorable temperatures [96,97], nutrients [98][99][100][101], and salinity [102,103]. Consequently, many studies have utilized the spectral indices, PRI and SIF retrievals, as indicators of stress and down-regulation of LUE and GPP [29,50,51,65,82,92,[104][105][106][107]. Our results lend support to those reported from previous studies that demonstrated that PRI and SIF retrievals were correlated to two important protective mechanisms (NPQ and chlorophyll fluorescence emissions), discarding excess absorbed solar radiation that could not be used in photosynthesis [3,29,54].…”

Far-red sun-induced chlorophyll fluorescence shows ecosystem-specific relationships to gross primary production: An assessment based on observational and modeling approaches

“…Various studies demonstrated the possibility to measure SIF at certain wavelengths on ground Rascher et al, 2009), from airborne platforms (Damm et al, 2014;Guanter et al, 2007;Zarco-Tejada, Gonzalez-Dugo, & Berni, 2012), and from satellites (Frankenberg et al, 2011;Guanter et al, 2014;Joiner et al, 2013). Recent research demonstrated SIF being sensitive to changes in photosynthesis, showing strong links to GPP at the level of leaves (Meroni et al, 2008;Middleton et al, 2002), plants Rossini et al, 2010), canopies (Zarco-Tejada, Morales, Testi, & Villalobos, 2013), and ecosystems (Frankenberg et al, 2011;Guanter et al, 2012).…”