Relationship between F730/F685 ratio of delayed fluorescence spectrum and plant heat resistance

In order to research the relationship between spectral properties of delayed fluorescence and plant heat resistance, three different samples (Bean Jinghuang No.3, Queen’s Crape Myrtle Lagelstroemia indica L, maize s5-168) were used as materials to experimentally study on the plant delayed fluorescence emission spectra at elevated temperatures (25-55°C). The maximal values of DF emission spectra at 685nm and 730nm were marked as F685 and F730 respectively. After analyzing the characteristic of temperature response curve of F730/F685 ratio, the cause of the formation of inflexion on the temperature response curve of F730/F685 ratio, and the temperature responses of five chlorophyll fluorescence parameters, it was concluded that DF emission spectra varied with the temperature-stress, and the responses of F730/F685 ratio of DF emission spectra to the temperature for the different samples could be a new and useful judgment to identify and evaluate the heat-resisting property of the samples. Moreover, the temperature inflexion of the temperature response curve of F730/F685 ratio could be a new identification index of plant heat resistance.