IRRADIANCE DEPENDENCE AND ACTION SPECTRA OF PHOTOSYNTHESIS .1. THEORETICAL CONSIDERATION

Analysis of the photosynthetic irradiance curves (IC), and action and quantum efficiency spectra on the basis of the model of Kok et al. (19 70) showed that under a low irradiance all IC, irrespective of sample absorbances, had non-linear (exponential) parts. Under a high irradian ce, the IC (especially those of higher situated sublayers) showed ''sa turation'', which was expressed as a decrease in the decline of the cu rves. The IC non-linearity was reflected in the shape of the photosynt hetic action spectra (AS). Under a low irradiance, the AS showed a dec rease (drop) in the spectral regions with low absorbances, i.e. betwee n 500 and 650 mn, as well as above 690 nm (Emerson's ''red drop effect ''). On the contrary, under higher irradiances an increase in quantum efficiency (QE) in the same regions was well-expressed. When IC were n on-linear, exact estimation of the photosynthetic AS and QE was much c omplicated and respective results should be accepted with a fair appro ach to accuracy.