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Effects of Simulated Acid Rain on Photosynthesis in Pinus massoniana and Cunninghamia lanceolata in Terms of Prompt Fluorescence, Delayed Fluorescence, and Modulated Reflection at 820 nm
Shu, P.; Gong, X.; Du, Y.; Han, Y.; Jin, S.; Wang, Z.; Qian, P.; Li, X. Effects of Simulated Acid Rain on Photosynthesis in Pinus massoniana and Cunninghamia lanceolata in Terms of Prompt Fluorescence, Delayed Fluorescence, and Modulated Reflection at 820 nm. Plants2024, 13, 622.
Shu, P.; Gong, X.; Du, Y.; Han, Y.; Jin, S.; Wang, Z.; Qian, P.; Li, X. Effects of Simulated Acid Rain on Photosynthesis in Pinus massoniana and Cunninghamia lanceolata in Terms of Prompt Fluorescence, Delayed Fluorescence, and Modulated Reflection at 820 nm. Plants 2024, 13, 622.
Shu, P.; Gong, X.; Du, Y.; Han, Y.; Jin, S.; Wang, Z.; Qian, P.; Li, X. Effects of Simulated Acid Rain on Photosynthesis in Pinus massoniana and Cunninghamia lanceolata in Terms of Prompt Fluorescence, Delayed Fluorescence, and Modulated Reflection at 820 nm. Plants2024, 13, 622.
Shu, P.; Gong, X.; Du, Y.; Han, Y.; Jin, S.; Wang, Z.; Qian, P.; Li, X. Effects of Simulated Acid Rain on Photosynthesis in Pinus massoniana and Cunninghamia lanceolata in Terms of Prompt Fluorescence, Delayed Fluorescence, and Modulated Reflection at 820 nm. Plants 2024, 13, 622.
Abstract
The effects of simulated acid rain (SAR) on the photosynthetic performance of subtropical coniferous species have not been thoroughly investigated. In this study, we treated two coniferous species, Pinus massoniana (PM) and Cunninghamia lanceolata (CL), with SAR and then analyzed photosynthetic activities via the simultaneous measurement of prompt fluorescence(PF), delayed fluorescence(DF), and modulated reflection at 820 nm(MR820). Following the low-pH SAR treatment, the I–P phase of the OJIP curves of PM and CL decreased significantly and then the K-band and L-band were detectable. The delayed fluorescence for both PM and CL decreased as the pH of the SAR solution decreased, with a more significant decrease in the I1 peak than in the I2 peak. According to the MR820 curve, the exposure to SAR stress inhibited the rapid decrease and slow increase in the MR820 transients of PM and CL. The gradients of the decreasing and increasing phases were lower for CL than for PM at pH 2.5. In addition, SAR decreased the light energy captured per unit area (ABS/CSm) and the quantum yield of electron transfer per unit area (ETO/CSm), but it increased the accumulation of QA−, thereby decreasing primary photochemical efficiency (TRO/CSm, φPO). These changes in photosystem II (PSII) resulted in a decrease in the maximum quantum yield of PSII (Fv/Fm) and the performance index (PIABS). Moreover, PSII was protected from thylakoid membrane photodamages through the increase in heat dissipation per unit area (DIO/CSm) in response to SAR. The increase in δRO as the pH of the SAR solution decreased was observed for PM, but not for CL. Considered together, the study findings suggest that SAR treatments can decrease chlorophyll contents and damage the OEC in PM and CL, which obstructs the transfer of electrons on the donor and acceptor sides of PSII. However, PM is better able to withstand SAR stress than CL, likely because of the activation of a protective mechanism (reflected by the change in δRO). Therefore, in coniferous forest areas severely affected by acid rain, CL may need to be protected more than PM.
Keywords
simulated acid rain; chlorophyll a fluorescence induction kinetics; 820-nm transmission kinetics; JIP-test; delayed fluorescence; coniferous trees
Subject
Biology and Life Sciences, Plant Sciences
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
