Photoinhibition and Active Oxygen Species Production in Detached Apple Leaves During Dehydration

摘要: In the course of dehydration, gas exchange and chlorophyll (Chl) fluorescence were measured under irradiance 800 μmol m−2 s−1 in detached apple leaves, production active oxygen species (AOS), hydrogen peroxide (H2O2), superoxide (O2 −), hydroxyl radical (−OH), singlet (1O2), determined. Leaf net photosynthetic rate (P N) was limited by stomatal non-stomatal factors at slight (2–3 h dehydration) moderate (4–5 water deficiency, respectively. Photoinhibition occurred after 3-h which defined decrease photosystem 2 (PS2) non-cyclic electron transport (P-rate). After 2-h an obvious rise H2O2 found as a result photorespiration rise. If inhibited sodium bisulfite (NaHSO3), post-irradiation transient increase Chl (Rfp) enhanced parallel with decline P-rate Mehler reaction. At leaf could be blocked glycine (Gly) or methyl viologen (MV) pre-treatment, MV more effective than Gly drought time. AOS (H2O2 O2 −), prior to photoinhibition produced from reaction leaves important dissipating photon energy excess demand CO2 assimilation. So effectively prevented way production.