Reduction kinetics of P700+ after far-red radiation (FR)-induced oxidation in intact tobacco leaves was examined by analysing the post-irradiation relaxation of 810-830 nm absorbance difference. The reduction curve could be de-convoluted distinctively into two or three exponential decaying components, depending on the FR irradiance, the treating and measuring temperatures, and the extent of dark adaptation. The multi-phasic kinetics of P700+ re-reduction upon the turning off of FR irradiation is related to the heterogeneity of electron transport around photosystem 1 in thylakoid membranes. and Ming-Xian Jin, Zheng-Ju Yao, Hualing Mi.