Phenotypic Response of Tobacco Leaves to Simulated Acid Rain and its Impact on Photosynthesis

As the number of urban vehicles in China continues to increase rapidly, acid rain from nitrogen wet deposition is becoming progressively more serious. This increases the local importance of breeding and screening for plant varieties resistant to acid rain. In the present study, we investigated the responses of leaf phenotype, net photosynthetic rate, and photosystem II (PSII) to wet deposition of acid rain (simulated by a mixture of sulfuric and nitric acid, at pH values of 3.5, 4.5 and 5.5) on leaves of tobacco seedlings grown in greenhouse conditions. The results showed that leaves sprayed with pH 3.5 acid rain lose green pigmentation and develop yellow spots as well as decrease in net photosynthetic rate. PSII responded to the acid rain treatment with obvious increases in energy flux trapped per reaction center (TRo/RC), dissipation of energy flux per cross section (DIo/RC), and the absorbed energy flux per reaction center (ABS/RC). However, there were decreases in photosynthetic performance index (PIABS), the accumulation of PSII receptor side QA (VJ), the QA maximum rate (Mo), and the heterogeneity of the PQ library (VI). It suggested that the wet deposition of simulated acid rain in tobacco leaves decreased the stability of thylakoid membranes, inhibited the electron transfer on the donor side and the receptor side of PSII, and destroyed the photosynthetic apparatus. © 2019 Friends Science Publishers