Chloroplast movements in leaves: Influence on chlorophyll fluorescence and measurements of light-induced absorbance changes related to ΔpH and zeaxanthin formation.

Light-induced chloroplast movements were found to cause changes in chlorophyll fluorescence emission, closely matching those in leaf absorptance, both in terms of the kinetics and the maximum extent of the changes observed in different species. The results demonstrate that chloroplast movements can have a significant effect on the efficiency of light utilization in photosynthesis. They further show that chloroplast movements need to be taken into account in measurements of fluorescence quenching and especially in measurements of light-induced optical changes used to monitor zeaxanthin formation and ΔpH associated light scattering in leaves. Means of minimizing and of adjusting for the influences of chloroplast movements in such measurements are discussed.