Effects of short-term simulated acid rain on the photosynthesis of Eremochloa ophiuroides

Effects of simulated acid rain on the characteristics of gas exchange and chlorophyll fluorescence in the leaves of Eremochloa ophiuroides were studied. The results showed that the net photosynthetic rate (Pn) and stomatal conductance (Gs) were decreased, while the intercelluer CO₂ concentration (Ci) was increased under acid rain stress, which indicate that the reductions of Pn were not due to stomatal factors. There was a faster decrease in actual PSII efficiency (ΦPSII) and electron transport rate (ETR) under acid rain stress. The efficiency of excitation energy captured by PS (Fv́/FḾ) were also decreased obviously. However, a slower decrease in photochemical quenching (qP) was noticed in Eremochloa ophiuroides. These results indicated that the reduction in ETR under acid rain condition was mainly due to the reduction of the efficiency of excitation energy capture of PSII. Nevertheless, the non-photochemical quenching (NPQ) was significantly higher under such conditions, thus helping to dissipate excess photon energy non-radiatively.