| Abstract: | Aims Our objectives were to introduce a mechanistic model of light-response of photosynthetic electron flow and to understand how the photosynthetic electron flow respond to light intensity and the characteristics of light-harvesting pigment molecules.Methods Light-responses of photosynthetic electron flow were measured in Lagedium sibiricum, Erigeron annuus and Aster tataricus by using a LI-6400-40B, and the curves were fitted by a mechanistic model of light-response of photosynthetic electron flow. Important findings (1) The mechanistic model of light-response of photosynthetic electron flow not only well described the light-response curves of photosynthetic electron flow in L. sibiricum, E. annuus and A. tataricus, but also obtained some key photosynthetic parameters, e.g. maximum photosynthetic electron flow, saturation irradiance and initial slope of the light-response curve; the fitted photosynthetic parameters were similar to the measured values. (2) The effective light absorption cross-section of light-harvesting pigment molecules quickly decreased with increasing irradiance in L. sibiricum, and showed slowest rate of decrease in E. annuus. (3) The light-harvesting pigment molecules in the lowest excited state increased most rapidly with increasing irradiance in L. sibiricum, and most slowly in E. annuus. In conclusion, compelling evidence indicates that decrease in effective absorption cross-section and increase in the number of light-harvesting pigments in the lowest excited state would reduce light energy absorption. |
