Changes of photosynthetic activity during natural depletion of nitrogen in a batch culture of Chlorella vulgaris were studied using chlorophyll a fluorescence-based methods. Complex analysis including JIP-test, multiexponential approximation, ...

A method to analyze the chlorophyll fluorescence transient was developed using approximation of the experimental signal by a multi-exponential series. Visualization of partial sums of the series made it possible to find the amplitudes and characteristic times for individual phases of the fluorescence induction curve. The method gave more rigid criteria of phase identification as compared with the current semi-empirical approach. Applied to the Chlamidomonas reinhardtii sulfur deprivation case, the method was efficient in finding visually indistinguishable phases of the fluorescence transient, thus allowing early detection of stress.