Detection of the onset of glyphosate-induced soybean plant injury through chlorophyll fluorescence signal extraction and measurement

Authors: ZHAO, FENG - Beihang University; GUO, YIQING - Beihang University; Huang, Yanbo; Reddy, Krishna; ZHAO, YANHUA - Beihang University; Molin, William

Submitted to: Journal of Applied Remote Sensing (JARS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2014
Publication Date: 1/21/2015
Citation: Zhao, F., Guo, Y., Huang, Y., Reddy, K.N., Zhao, Y., Molin, W.T. 2015. Detection of the onset of glyphosate-induced soybean plant injury through chlorophyll fluorescence signal extraction and measurement. Journal of Applied Remote Sensing (JARS). 9(1):1-12.

Interpretive Summary: Chlorophyll fluorescence of crop plants can be a useful indicator to quantify the onset of crop stress. In this study, the scientists of Beihang University in China and USDA-ARS Crop Production Systems Research Unit in Stoneville, Mississippi, measured chlorophyll fluorescence to assess the onset of crop injury from glyphosate. Results indicated that the measured fluorescence parameters are sensitive to glyphosate treatment starting at and beyond 24 hours after treatment. Moreover, the fluorescence spectra of the treated groups can be significantly distinguished from each other 48 hours after treatment and some chlorophyll fluorescence-related spectral indices are also shown to be useful in detection of the glyphosate injury. This study provides proof that chlorophyll fluorescence can be effective in detecting the onset of glyphosate-induced leaf injury in practice.

Technical Abstract: In this study, Chlorophyll Fluorescence (ChlF) was used to detect the onset of soybean plant injury from glyphosate, the most widely used herbicide. Thirty-six pots of non-glyphosate-resistant soybean (cultivar FM955LL) were randomly divided into three groups and treated with different doses of glyphosate solutions. The three treatment groups were control (CTRL) group (with no glyphosate treatment), 0.25X group (treated with 0.217 kg•ae/ha solution of glyphosate), and 0.5X group (treated with 0.433 kg•ae/ha solution of glyphosate). Two kinds of fluorescence data, steady-state fluorescence spectra and Kautsky effect parameters, were extracted and generated from the measurements in the glyphosate treatment experiment. Reflectance-based indices, which were potentially related to ChlF, were also calculated from leaf reflectance spectra acquired synchronously with the fluorescence measurements. These data were processed and analyzed to study their response to the glyphosate treatments. Results indicate that steady-state fluorescence spectra of the three groups can be significantly distinguished from each other 48 Hours After Treatment (HAT) and later. Four Kautsky effect parameters, Fv, Fv/Fm, Area, and PI, are parameters sensitive to glyphosate treatment, showing significant differences between the CTRL group and treated groups at 24 HAT and among the three groups at and beyond 48 HAT. Moreover, ChlF-related spectral indices, R675•R690/R6832 and R690/R655, are also shown to be useful in detection of the glyphosate injury. Results presented in this paper demonstrate that ChlF is effective in detecting the onset of glyphosate-induced crop stress, and has the potential to be further developed into practical use.