Watanabe Makoto, Li Jing, Matsumoto Misako, Aoki Takuro, Ariura Ryo, Fuse Tsuyoshi, Zhang Yazhuo, Kinose Yoshiyuki, Yamaguchi Masahiro, Izuta Takeshi
Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan.
Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan.
Environ Pollut. 2022 Jul 1;304:119233. doi: 10.1016/j.envpol.2022.119233. Epub 2022 Mar 28.
Ozone (O) is a phytotoxic air pollutant, the adverse effects of which on growth and photosynthesis are modified by other environmental factors. In this study, we examined the combined effects of O, elevated CO, and soil nitrogen supply on Siebold's beech seedlings. Seedlings were grown under combinations of two levels of O (low and two times ambient O concentration), two levels of CO (ambient and 700 ppm), and three levels of soil nitrogen supply (0, 50, and 100 kg N ha year) during two growing seasons (2019 and 2020), with leaf photosynthetic traits being determined during the second season. We found that elevated CO ameliorated O-induced reductions in photosynthetic activity, whereas the negative effects of O on photosynthetic traits were enhanced by soil nitrogen supply. We observed three-factor interactions in photosynthetic traits, with the ameliorative effects of elevated CO on O-induced reductions in the maximum rate of carboxylation being more pronounced under high than under low soil nitrogen conditions in July. In contrast, elevated CO-induced amelioration of the effects of O on stomatal function-related traits was more pronounced under low soil nitrogen conditions. Although we observed several two- or three-factor interactions of gas and soil treatments with respect to leaf photosynthetic traits, the shoot to root dry mass (S/R) ratio was the only parameter for which a significant interaction was detected among seedling growth parameters. O caused a significant increase in S/R under ambient CO conditions, whereas no similar effects were observed under elevated CO conditions. Collectively, our findings reveal the complex interactive effects of elevated CO and soil nitrogen supply on the detrimental effects of O on leaf photosynthetic traits, and highlight the importance of taking into consideration differences between the responses of CO uptake and growth to these three environmental factors.
臭氧（O）是一种具有植物毒性的空气污染物，其对植物生长和光合作用的不利影响会受到其他环境因素的改变。在本研究中，我们研究了臭氧、升高的二氧化碳浓度和土壤氮供应对日本榉树幼苗的综合影响。在两个生长季节（2019年和2020年）中，幼苗在两种臭氧水平（低水平和环境臭氧浓度的两倍）、两种二氧化碳水平（环境浓度和700 ppm）以及三种土壤氮供应水平（0、50和100 kg N ha⁻¹ year⁻¹）的组合条件下生长，并在第二个季节测定叶片光合特性。我们发现，升高的二氧化碳浓度减轻了臭氧诱导的光合活性降低，而土壤氮供应增强了臭氧对光合特性的负面影响。我们观察到光合特性存在三因素相互作用，7月在高土壤氮条件下，升高的二氧化碳浓度对臭氧诱导的羧化最大速率降低的缓解作用比低土壤氮条件下更明显。相反，在低土壤氮条件下，升高的二氧化碳浓度对臭氧气孔功能相关特性影响的缓解作用更明显。尽管我们观察到气体和土壤处理在叶片光合特性方面存在几个二因素或三因素相互作用，但地上部与根部干质量（S/R）比是在幼苗生长参数中唯一检测到显著相互作用的参数。在环境二氧化碳条件下，臭氧导致S/R显著增加，而在升高的二氧化碳浓度条件下未观察到类似影响。总的来说，我们的研究结果揭示了升高的二氧化碳浓度和土壤氮供应对臭氧对叶片光合特性的有害影响的复杂相互作用，并强调了考虑二氧化碳吸收和生长对这三种环境因素响应差异的重要性。
