Estimation of protein content in plant leaves using spectral reflectance : a case study in euonymus Japonica

Reflectance spectroscopy has been widely applied in the field of environmental studies. In this study, a low-cost, rapid, and nondestructive method using spectral reflectance was explored to evaluate protein concentrations in plant leaves of Euonymus japonica. Proteins in leaf samples were extracted and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and five specific protein bands of interest were identified and quantified. Correlation analysis indicated that spectral reflectance had significant relationships with ribulose bisphosphate carboxylase a (r = -0.43) and chlorophyll a-b binding protein (r = 0.53). A linear regression model and a quadratic regression model were formulated to directly and rapidly estimate the concentration of these two proteins with R 2 = 0.61 and 0.7, respectively. To more accurately estimate the concentration of proteins, a precise inversion was established by a back propagation neutral network model using plant spectral absorption and position parameters, and the R 2 values for proteins ribulose bisphosphate carboxylase, chlorophyll a-b binding protein, oxygen evolving enhancer protein, and ATP synthase subunit beta were 0.90, 0.91, 0.91, and 0.93, respectively. The models established in this study were shown to be useful tools for studies of plant biochemical components and health under different environmental conditions.Department of Land Surveying and Geo-Informatic