[Analysis of photosynthesis light curves under continuous illumination]

A mathematical description of the photosynthesis light curve is proposed taking into account the type of photosynthetic unit (PSU) organization (unicentral or multicentral), energy migration between the PSU, and the nonlinear character of the dark process limiting the rate. In the case of unicentral PSU the light curve is described by the expression: I = v (1--yv)/(1--v) where I is light intensity; v is relative rate of photosynthesis (relative to the maximal rate); y is the parameter which determines the shape of the curve. Its value depends on the efficiency of energy migration between PSU and on the ratio of the limiting dark reactions rates. The variations of the value from 1 to 0 give different known types of light curves. Coordinates are proposed in which the curves for multicentral and unicentral PSU are distinguished and parameter is estimated. Experimental light curves for a number of marine algae correspond to the supposition of the PSU unicentral organization, with y = 0.9.