Abstract
We have characterized a new commercial chlorophyll (Chl) and flavonoid (Flav) meter called Dualex 4 Scientific (Dx4). We compared this device to two other Chl meters, the SPAD-502 and the CCM-200. In addition, Dx4 was compared to the leaf-clip Dualex 3 that measures only epidermal Flav. Dx4 is factory-calibrated to provide a linear response to increasing leaf Chl content in units of µg cm–2, as opposed to both SPAD-502 and CCM-200 that have a non-linear response to leaf Chl content. Our comparative calibration by Chl extraction confirmed these responses. It seems that the linear response of Dx4 derives from the use of 710 nm as the sampling wavelength for transmittance. The major advantage of Dx4 is its simultaneous assessment of Chl and Flav on the same leaf spot. This allows the generation of the nitrogen balance index (NBI) used for crop surveys and nitrogen nutrition management. The Dx4 leaf clip, that incorporates a GPS receiver, can be useful for non-destructive estimation of leaf Chl and Flav contents for ecophysiological research and ground truthing of remote sensing of vegetation. In this work, we also propose a consensus equation for the transformation of SPAD units into leaf Chl content, for general use.
Highlights
The Dualex 4 Scientific (Dx4) is the last generation of chlorophyll (Chl) meters that appeared recently on the market
It was followed by a series of commercial devices: Fuji GM-1 Chlorophyll meter and Minolta SPAD-501 that are not produced any more, SPAD-502 (SPAD hereafter) and Hydro N-tester both produced by Minolta (Konica-Minolta, Tokyo, Japan), CCM-200 (CCM hereafter) (Opti-Sciences, Hudson, NH), CL-01 (Hansatech, King’s Lynn, United Kingdom) and Dualex 4 Scientific (FORCE-A, Orsay, France)
The accuracy of the fitted models and of the prediction of Chl content was assessed by the coefficient of determination (R2), the residual sum of squares (RSS), the root mean square error (RMSE), the BIAS and by the standard error of prediction corrected for the BIAS (SEPC)
Summary
A new optical leaf-clip meter for simultaneous non-destructive assessment of leaf chlorophyll and epidermal flavonoids. Received 31 January 2012; revised 6 March 2012 doi:10.1111/j.1399-3054.2012.01639.x. We have characterized a new commercial chlorophyll (Chl) and flavonoid (Flav) meter called Dualex 4 Scientific (Dx4). We have characterized a new commercial chlorophyll (Chl) and flavonoid (Flav) meter called Dualex 4 Scientific (Dx4) We compared this device to two other Chl meters, the SPAD-502 and the CCM-200. The major advantage of Dx4 is its simultaneous assessment of Chl and Flav on the same leaf spot. This allows the generation of the nitrogen balance index (NBI) used for crop surveys and nitrogen nutrition management. We propose a consensus equation for the transformation of SPAD units into leaf Chl content, for general use
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