United Graduate School of Agricultural Science, 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.
Sci Total Environ. 2020 May 10;716:137008. doi: 10.1016/j.scitotenv.2020.137008. Epub 2020 Jan 31.
Ozone (O) in the troposphere, an air pollutant with phytotoxicity, is considered as a driver of global warming, because it reduces plant carbon fixation. Recently, a process-based plant growth model has been used in evaluating the O impacts on plants (Schauberger et al., 2019). To make the evaluation more rigorous, we developed a plant growth model and clarified the key factors driving O-induced change in the whole-plant carbon fixation amount (C). Fagus crenata seedlings were exposed to three O levels (charcoal-filtered air or 1.0- or 1.5-folds ambient [O]) with three soil fertilization levels (non-, low-, or high-fertilized), i.e., a total of nine treatments. The C was reduced in non- and low-fertilized treatments but was unaffected in high-fertilized treatment by O fumigation. Our plant growth model could simulate C accurately (<10% error) by considering the impacts of O on plant leaf area and photosynthetic capacities, including maximum velocities of carboxylation and electron transport (V and J, respectively), and the initial slope and convexity of the curve of the electron transport velocity response to photosynthetic photon flux density (φ and θ, respectively). Furthermore, the model revealed that changes in V and J, φ and θ, or leaf area, caused by 1.5-folds the ambient [O] fumigation resulted in the following C changes: -1.6, -5.8, or -16.4% in non-fertilized seedlings, -4.1, -4.4, or -9.3% in low-fertilized seedlings, and -4.6, -7.6, or +5.8% in high-fertilized seedlings. Therefore, photosynthetic capacities (particularly φ and θ) and leaf area are important factors influencing the impact of O on C of F. crenata seedlings grown under various fertilization levels. Further, the impacts of O and soil nutrient on these photosynthetic capacities and plant leaf area should be considered to predict O-induced changes in carbon fixation by forest tree species using the process-based plant growth model.
对流层中的臭氧（O）是一种具有植物毒性的空气污染物，被认为是全球变暖的驱动因素，因为它会降低植物的碳固定能力。最近，一种基于过程的植物生长模型被用于评估 O 对植物的影响（Schauberger 等人，2019 年）。为了使评估更加严格，我们开发了一种植物生长模型，并阐明了驱动 O 诱导的整个植物碳固定量（C）变化的关键因素。用三种臭氧水平（木炭过滤空气或 1.0 或 1.5 倍环境[O]）和三种土壤施肥水平（不施肥、低施肥或高施肥）处理日本柳杉幼苗，即总共 9 种处理。在不施肥和低施肥处理中，臭氧熏蒸降低了 C，但在高施肥处理中不受影响。我们的植物生长模型可以通过考虑臭氧对植物叶面积和光合能力的影响来准确模拟 C（<10%的误差），包括羧化和电子传递的最大速度（V 和 J）以及电子传递速度对光合光子通量密度的响应曲线的初始斜率和凸度（φ 和 θ）。此外，该模型揭示了 1.5 倍环境[O]熏蒸引起的 V 和 J、φ 和 θ 或叶面积的变化导致非施肥幼苗的 C 变化：-1.6%、-5.8%或-16.4%，低施肥幼苗的 C 变化：-4.1%、-4.4%或-9.3%，高施肥幼苗的 C 变化：-4.6%、-7.6%或+5.8%。因此，光合能力（特别是φ和θ）和叶面积是影响不同施肥水平下日本柳杉幼苗 O 对 C 影响的重要因素。此外，应该考虑 O 和土壤养分对这些光合能力和植物叶面积的影响，以便使用基于过程的植物生长模型预测森林树种因 O 引起的碳固定变化。
