Alteration in delayed fluorescence characterize the effect of heat stress on plants

High temperature affects the photosynthetic functions of plants by its effects on the rate of chemical reactions and on structural organization. Delayed fluorescence originated from the reaction center of photosystem II (PSII) during the photosynthesis process shortly after stopped illumination. With lamina of soybean as a testing model, the effects of high temperature stress on plant photosynthesis capability were studied with various spectral analysis methods. Experimental results show that DF spectrum and Excitation spectrum can probably characterize the changes of soybean photosynthesis capability after different high temperature treatments. Meanwhile, the injury and harm degree of heat stress on soybean leaves were further studied by the variability of its chloroplast absorption spectrum. DF spectroscopy method may provide a new approach for fast detection of the effects of environment stresses on plant photosynthesis capability.