Abstract
Accurate measurement of leaf chlorophyll concentration (LChl) in the field using a portable chlorophyll meter (PCM) is crucial to support methodology development for mapping the spatiotemporal variability of crop nitrogen status using remote sensing. Several PCMs have been developed to measure LChl instantaneously and non-destructively in the field, however, their readings are relative quantities that need to be converted into actual LChl values using conversion functions. The aim of this study was to investigate the relationship between actual LChl and PCM readings obtained by three PCMs: SPAD-502, CCM-200, and Dualex-4. Field experiments were conducted in 2016 on four crops: corn (Zea mays L.), soybean (Glycine max L. Merr.), spring wheat (Triticum aestivum L.), and canola (Brassica napus L.), at the Central Experimental Farm of Agriculture and Agri-Food Canada in Ottawa, Ontario, Canada. To evaluate the impact of other factors (leaf internal structure, leaf pigments other than chlorophyll, and the heterogeneity of LChl distribution) on the conversion function, a global sensitivity analysis was conducted using the PROSPECT-D model to simulate PCM readings under different conditions. Results showed that Dualex-4 had a better performance for actual LChl measurement than SPAD-502 and CCM-200, using a general conversion function for all four crops tested. For SPAD-502 and CCM-200, the error in the readings increases with increasing LChl. The sensitivity analysis reveals that deviations from the calibration functions are more induced by non-uniform LChl distribution than leaf architectures. The readings of Dualex-4 can have a better ability to restrict these influences than those of the other two PCMs.
Highlights
Estimation of plant traits using remote sensing data, such as leaf nitrogen concentration, leaf chlorophyll concentration (LChl) and leaf area index (LAI), is important for mapping the spatiotemporal variability of crop and soil conditions, and modeling crop nutrient balance, and crop productivity [1,2,3]
The absolute pigment concentration ranged from 25.6 to 83.6 μg cm−2 for LChl (μ = 48.4 μg cm−2 and coefficient of variance (CV) = 25.3%) and 3.6 to 13.3 μg cm−2 for Car (CV = 28.0%). These suggest that the variability of the SPAD-502 readings and the Dualex-4-chlorophyll index (Chl) readings was closer to the variability of actual LChl than that of the CCM-200-CCI
We evaluated the performances of three commonly used portable chlorophyll meters (SPAD-502, CCM-200 and Dualex-4) in measuring the leaf chlorophyll concentration (LChl) of four different crops
Summary
Estimation of plant traits using remote sensing data, such as leaf nitrogen concentration, leaf chlorophyll concentration (LChl) and leaf area index (LAI), is important for mapping the spatiotemporal variability of crop and soil conditions, and modeling crop nutrient balance, and crop productivity [1,2,3]. There has been rapid development in new satellite sensors, such as multispectral satellite sensors with red-edge (680–750 nm) reflectance measurements (e.g., Sentinel-2 and VENμS) [16,17], the VNIR-SWIR hyperspectral satellite sensors (e.g., HyspIRI and EnMAP) [18,19], and the multi- and hyperspectral imaging systems mounted on a UAV system [19]. These sensors possess the red-edge or hyperspectral reflectance that is highly sensitive to changes in LChl [4]. Accurate in situ LChl measurements are essential for developing and validating remote-sensing LChl estimation models
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
