Comparison of the effect of excessive light on chlorophyll fluorescence (77K) and photon yield of O2 evolution in leaves of higher plants.

摘要: High-light treatments (1750–2000 μmol photons m−2 · s−1) of leaves from a number higher-plant species invariably resulted in quenching the maximum 77K chlorophyll fluorescence at both 692 and 734 nm (FM, FM, 734). The response instantaneous (FO, 692) was complex. In some FO, increased dramatically others it quenched, yet showed no marked, consistent change. Regardless an apparently linear relationship obtained between ratio variable to (FV/FM, photon yield O2 evolution, indicating that photoinhibition affects these two variables approximately same extent. Treatment CO2−free gas stream containing 2% 98% N2 under weak light (100 general fully reversible nm. this case were caused by non-radiative energy dissipation pigment bed. We propose high-light can have least different, concurrent effects on leaves. One results damage photosystem II (PSII) reaction-center complex leads rise 692; other This had much longer relaxation time than reported for ΔpH-dependent algae chloroplasts. Sun leaves, whose FV/FM, ratios little affected exposure normal air, suffered pronounced when made conditions prevent photosynthetic exchange (2% O2, 0% CO2). However, they still less susceptible shade higher capacity via photosynthesis is not only cause their lower susceptibility. rate constant recovery mature sun differences continuous repair may part account difference susceptibility photoinhibition.