Combination of elevated CO₂ concentration and elevated temperature and elevated temperature only promote photosynthesis of Quercus mongolica seedlings
2008
Wang, X. -W | Zhao, M | Mao, Z. -J | Zhu, S. -Y | Zhang, Delu | Zhao, X. -Z
One-year-old oak (Quercus mongolica Fisch.) seedlings were grown in growth chambers for 30 days to investigate the effects of the combination of elevated CO₂ concentration ([CO₂], 700 μmol/mol) and temperature (ambient T + 4°C) and only elevated temperature (ambient T +4°C) on leaf gas exchange, chlorophyll a fluorescence, and chlorophyll content. In the growth chambers, natural conditions of the Maoershan mountain regions of Heilongjiang Province (45-46°N, 127-128°E) of China for the average growth season were simulated. The results showed that the maximum net photosynthetic rate (P Nmax) was [almost equal to] 1.64 times greater at elevated temperature than at ambient temperature. The irradiance saturation point (I s), apparent quantum yield (AQY), maximum photosystem II efficiency (F v/F m), and chlorophyll content significantly increased, while irradiance compensation point (I c) was not affected by elevated temperature. The combination of elevated [CO₂] and temperature also significantly increased P Nmax by approximately 34% but much lower than that under elevated temperature only. In the case of factor combination, dark respiration (R d), I c, F v/F m, and total chlorophyll content increased significantly, while I s and AQY were not affected. Moreover, under elevated [CO₂] and temperature, R d and I c, F v/F m were significantly higher than under elevated temperature only. The results indicated that the combination of elevated [CO₂] and temperature expected in connection with the further global climate change may affect carbon storage of the coenotype of Q. mongolica in this region of China.
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