Key Laboratory of Agrometeorology of Jiangsu Province, School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, Jiangsu 210044, China.
Sci Total Environ. 2021 May 1;767:144588. doi: 10.1016/j.scitotenv.2020.144588. Epub 2021 Jan 2.
A modified Ball-Berry-Leuning model of stomatal conductance was applied to data from fully open-air ozone (O)-enrichment experiments with winter wheat (Triticum aestivum L.). The O fluxes reaching both surface of cell wall (F) and plasmalemma (F) were estimated considering apoplastic ascorbate, a major scavenger of O. The difference (D) between F and F was defined as detoxification capacity of O by reaction with ascorbate in the leaf apoplast (ASC). The accumulated stomatal O flux above D nmol O m s (AF) and the accumulated F (AF) were calculated over the optimal integration period covering the whole reproductive development of wheat, and used to derive OAF yield-response relationships in comparison with POD (phytotoxic O dose above a threshold of Y nmol m s) and AOT40 (accumulated O dose over a threshold of 40 ppb). There was a good agreement between the observed and modeled values of ASC and stomatal conductance. AF and AF performed better than POD and AOT40 in terms of R and intercept. However, the AF metric was more suitable for assessing grain yield loss due to lower sensitivity of the regression slope to variations in the input parameters, compared with AF. The average critical level (CL) of four cultivars for 5% grain-yield reduction was 1.53 mmol m using POD and 2.81 mmol m using AF, with the latter being well above the POD-derived value for European cultivars (1.3 mmol m). The minimum hourly averaged O concentration contributed to CLs was below 20 ppb according to AF, a value that is lower than that suggested by POD (≈27 ppb). O flux-response relationships and CLs on the basis of quantified detoxification capacity shall facilitate the understanding of the different degrees of susceptibility to O among species or cultivars, and improve the assessments of O impacts on plants.
采用改良的 Ball-Berry-Leuning 气孔导度模型，对冬小麦（Triticum aestivum L.）完全开放空气臭氧（O）富集实验的数据进行了分析。考虑到质外体抗坏血酸（一种主要的 O 清除剂），估算了到达细胞壁表面（F）和质膜（F）的 O 通量。定义 F 和 F 之间的差值（D）为 O 通过与叶片质外体中的抗坏血酸反应进行解毒的能力（ASC）。在整个小麦生殖发育的最佳积分期内，计算了气孔 O 通量累积量（AF）超过 D（nmol O m s）的部分和累积 F（AF），并将其与 POD（超过 Y nmol m s 阈值的毒性 O 剂量）和 AOT40（超过 40 ppb 阈值的累积 O 剂量）进行了比较，以得出 OAF 产量响应关系。观察到的和模型化的 ASC 和气孔导度值之间存在良好的一致性。在 R 和截距方面，AF 和 AF 比 POD 和 AOT40 表现更好。然而，与 AF 相比，由于回归斜率对输入参数变化的敏感性较低，AF 指标更适合评估因谷物产量降低而造成的损失。使用 POD 时，四个品种的 5%谷物产量降低的平均临界水平（CL）为 1.53 mmol m，使用 AF 时为 2.81 mmol m，后者明显高于欧洲品种的 POD 衍生值（1.3 mmol m）。根据 AF，导致 CL 的最小每小时平均 O 浓度低于 20 ppb，这一值低于 POD 建议的值（约 27 ppb）。基于量化的解毒能力的 O 通量响应关系和 CL 将有助于理解物种或品种对 O 的不同敏感性程度，并提高对植物的 O 影响的评估。
