Assessment of Portable Chlorophyll Meters for Measuring Crop Leaf Chlorophyll Concentration

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.

Short-Term Pre-Harvest UV-B Supplement Enhances the Polyphenol Content and Antioxidant Capacity of Ocimum basilicum Leaves during Storage

“…Considering the Chl Index, other studies have described, in several plant species, a linear correlation with the chlorophyll content in non-stressed leaves [ 63 , 75 ]. We did not observe a significant correlation between the total chlorophyll content and the Chl Index because we considered detached leaves under storage.…”

Estimating Plant Nitrogen Concentration of Maize Using a Leaf Fluorescence Sensor across Growth Stages

“…Merr. ), spring wheat (Triticum aestivum L.), and canola (Brassica napus L.) (R 2 = 0.69-0.90) [26]. Cartelat et al [27] showed a strong linear relationship between phenolics (Phen) measured by Dualex sensor and leaf N concentration (LNC) (R 2 = 0.76) and further displayed the correlation between Phen and N nutrition index (NNI) (r = −0.60) for wheat.…”

Effects of Nitrogen and Sulfur Sprays on the Growth and Production of Broccoli Brassica Oleracea var. Italica L.

“…italic JASSMINE F1 Hybrid (from DELTA seeds, Holland) cultivars, The following parameters for growth and yield characteristics were recorded on randomly selected plants: plant height (cm), leaves weight (gm), number of leaves per plant, leaf area (dm 2 .plant -1 ), plant stem diameter (cm), fresh root weight (gm), and weight of the main curd (gm). In addition, chlorophyll content index (CCI) was determined with a portable chlorophyll meter (OPTI-SCIENCES model CCM-200 plus / USA) at optical absorbance of 633 nm (Chlorophyll) and 931 nm (Near Infra-Red) (21).…”