Research Article | Open Access

Volume 2023 |Article ID 0034 | https://doi.org/10.34133/plantphenomics.0034

Determination of Fv/Fm from Chlorophyll a Fluorescence without Dark Adaptation by an LSSVM Model

Qian Xia,¹ Hao Tang,¹ Lijiang Fu,¹ Jinglu Tan,² Govindjee Govindjee,³ and Ya Guo ¹

¹Key Laboratory of Advanced Process Control for Light Industry, Ministry of Education, Jiangnan University, Wuxi 214122, China
²Department of Biomedical, Biological and Chemical Engineering, University of Missouri, Columbia, MO 65211, USA
³Center of Biophysics and Quantitative Biology, Department of Biochemistry and Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

Abstract

Evaluation of photosynthetic quantum yield is important for analyzing the phenotype of plants. Chlorophyll a fluorescence (ChlF) has been widely used to estimate plant photosynthesis and its regulatory mechanisms. The ratio of variable to maximum fluorescence, Fv/Fm, obtained from a ChlF induction curve, is commonly used to reflect the maximum photochemical quantum yield of photosystem II (PSII), but it is measured after a sample is dark-adapted for a long time, which limits its practical use. In this research, a least-squares support vector machine (LSSVM) model was developed to explore whether Fv/Fm can be determined from ChlF induction curves measured without dark adaptation. A total of 7,231 samples of 8 different experiments, under diverse conditions, were used to train the LSSVM model. Model evaluation with different samples showed excellent performance in determining Fv/Fm from ChlF signals without dark adaptation. Computation time for each test sample was less than 4 ms. Further, the prediction performance of test dataset was found to be very desirable: a high correlation coefficient (0.762 to 0.974); a low root mean squared error (0.005 to 0.021); and a residual prediction deviation of 1.254 to 4.933. These results clearly demonstrate that Fv/Fm, the widely used ChlF induction feature, can be determined from measurements without dark adaptation of samples. This will not only save experiment time but also make Fv/Fm useful in real-time and field applications. This work provides a high-throughput method to determine the important photosynthetic feature through ChlF for phenotyping plants.