ABSTRACT
To examine the effects of elevated CO2 concentrations on chlorophyll fluorescence of rice leaf, a field experiment was conducted with automatic control system of CO2 concentration in open top-chambers (OTCs). There were three treatments, including atmospheric CO2 concentration (CK), CK+80 µmol·mol-1 CO2 (T1), and CK+200 µmol·mol-1 CO2 (T2). The fast chlorophyll fluorescence induction dynamic curves of flag leaves were measured using the plant efficiency analyzer at the main growth stages of rice. The results showed that T1 treatment significantly increased quantum yield for electron transfer (φEo), maximum photochemical efficiency (Fv/Fm), and performance index (PIABS), but decreased quantum yield for energy dissipation (φDo) at the flowe-ring, milk grain, ripening, and full ripeness stages. The values of φEo, Fv/Fm, and PIABS were increased by 7.3%-23.3%, 3.1%-7.1%, and 46.2%-93.0%, respectively. The φDo values were decreased by 10.3%-20.5%. T2 treatment significantly decreased φEo, Fv/Fm, PIABS by 68.7%, 41.4%, and 93.4%, respectively, but increased φDo by 78.4% at the jointing stage. T2 treatment significantly increased φEo, Fv/Fm, PIABS by 11.6%-19.8%, 4.8%-6.8%, and 53.0%-72.6%, respectively, and decreased φDo by 7.7%-19.4% at the flowering, milk grain, and ripening stages. Our results suggested that elevated CO2 concentration (80, 200 µmol·mol-1) would promote photosynthetic electron transport of PS2 in flag leaves of rice.
