Abstract: The light response curve of photosynthetic electron flow is an important tool to investigate plant physiology and ecology. It can provide a theoretical basis for quantifying the absorption and transmission of light energy in primary reaction. In this paper, the mathematical characteristics, the advantages, and the potential weaknesses in practical application and research trends of the light response models of photosynthetic electron flow are reviewed and discussed. The primary reaction, which includes absorption of light energy, excitation and de-excitation of photosynthetic pigment molecules (including photochemical reaction, fluorescence emission and heat dissipation), and electron flow (J) steming from charge separation in the PSII reaction center caused by exciton resonance, is consisted by a series of complex physical and biochemical reactions. The classical and semi-mechanistic models of light response curve of photosynthetic electron flow are difficult to explain the dynamic down-regulation of PSII, light adaptation and light protection of algae and plant because they did not involve or only partly involved the primary reaction process. However, the mechanism model takes into account the important role of the physical parameters of the photosynthetic pigment molecule (e.g., the eign-absorption cross-section of light energy(?ik), the average lifetime of the molecule in the lowest excited state (?min), the energy level degeneracy of the molecule and the number of photosynthetic pigment molecules in the excited state (Nk)) in the whole primary reaction process, it can not only obtain the Jmax and PARsat of algae and plant, but also get some important physical parameters such as ?ik and ?min. Meanwhile also it can obtain the laws about light-response of the effective light energy absorption cross-section ( ) and of Nk. It may be the development direction of the mechanism model of photosynthetic electron flow response to light in the future when the mechanistic model was coupled with some environmental factors (e.g., temperature and CO2 concentration) and the relationship between light intensity and and Nk were determined.

Key words: photosynthetic electron flow, primary reaction, classical model, semi-mechanistic model, mechanistic model