Effect of EDDS Treatments on FTIR-ATR, SEM-EDXS Features and Physiological Characteristics of Coleus blumei Roots under Se Stress

To understand the physiological mechanism of -ethylenediamine disuccinic acid (EDDS) inducing plant resistance to selenium (Se), a hydroponic experiment with different concentrations of EDDS (0, 0.5, 1.0, 1.5, 2.5, and 5.0 mmol/L) was conducted to investigate the chemical component changes in Coleus blumei roots under Se stress (1.0 mg/L) using scanning electron microscopy-X-ray energy dispersive spectroscopy (SEM-EDXS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) with physiological trait changes. Results showed that the peak shape of the C. blumei root component remained invariable, as observed by FTIR-ATR spectra. A significant transmission peak shift of some function groups, such as hydroxyl groups, acid amide groups and fingerprint region, was obtained when they participated in the process of absorbing Se. There was good correspondence between the changes in the physiological characteristics and changes in samples based on the indices of wave number absorbance of FTIR-ATR spectra, and FTIR-ATR was more sensitive and convenient. SEM-EDXS analysis showed that the element contents of K, Mg, Fe and Si in the roots increased and the content of Ca decreased with increasing EDDS concentration.