Abstract Ozone (O3) is a toxic oxidative air pollutant, with significant detrimental effects on crops. Sugarcane (Saccharum spp.) is an important crop with no O3 risk assessment performed so far. This study aimed to assess O3 risk to sugarcane plants by using exposure-based indices (AOT40 and W126) based on O3 concentrations in the air, and the flux-based index (PODy, where y is a threshold of uptake) that considers leaf O3 uptake and the influence of environmental conditions on stomatal conductance (gsto). Two sugarcane genotypes (IACSP94-2094 and IACSP95-5000) were subjected to a 90-day Free-Air Controlled Experiment (FACE) exposure at three levels of O3 concentrations: ambient (Amb); Amb x1.2; and Amb x1.4. Total above-ground biomass (AGB), stalk biomass (SB) and leaf biomass (LB) were evaluated and the potential biomass production in a clean air was estimated by assuming a theoretical clean atmosphere at 10 ppb as 24 h O3 average. The Jarvis-type multiplicative algorithm was used to parametrize gsto including environmental factors i.e. air temperature, light intensity, air vapor pressure deficit, and minimum night-time temperature. Ozone exposure caused a negative impact on AGB, SB and LB. The O3 sensitivity of sugarcane may be related to its high gsto (∼535 mmol H2O m−2 s−1). As sugarcane is adapted to hot climate conditions, gsto was restricted when the current minimum air temperature (Tmin) was below ∼14 °C and the minimum night-time air temperature of the previous day (Tnmin) was below ∼7.5 °C. The flux-based index (PODy) performed better than the exposure-based indices in estimating O3 effect on biomass losses. We recommend a y threshold of 2 nmol m−2 s−1 to incorporate O3 effects on both AGB and SB and 1 nmol m−2 s−1 on LB. In order not to exceed 4% reduction in the growth of these two sugarcane genotypes, we recommend the following critical levels: 1.09 and 1.04 mmol m−2 POD2 for AGB, 0.91 and 0.96 mmol m−2 POD2 for SB, and 3.00 and 2.36 mmol m−2 POD1 for LB of IACSP95-5000 and IACSP94-2094, respectively.

中文翻译：

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基于暴露和通量的甘蔗植物臭氧风险评估

摘要 臭氧（O3）是一种有毒的氧化性空气污染物，对农作物有显着的不利影响。甘蔗 (Saccharum spp.) 是一种重要的作物，目前尚未进行 O3 风险评估。本研究旨在通过使用基于空气中 O3 浓度的基于暴露的指数（AOT40 和 W126）以及考虑叶片 O3 的基于通量的指数（PODy，其中 y 是吸收阈值）来评估 O3 对甘蔗植物的风险吸收和环境条件对气孔导度 (gsto) 的影响。两种甘蔗基因型（IACSP94-2094 和 IACSP95-5000）在三个 O3 浓度水平下进行 90 天的自由空气控制实验 (FACE) 暴露：环境 (Amb)；安姆 x1.2；和 Amb x1.4。总地上生物量 (AGB)，评估了茎生物量 (SB) 和叶生物量 (LB)，并通过假设 10 ppb 的理论清洁大气作为 24 小时 O3 平均值来估计清洁空气中潜在的生物量产量。Jarvis 型乘法算法用于参数化 gsto，包括环境因素，即气温、光照强度、空气蒸气压不足和最低夜间温度。臭氧暴露对 AGB、SB 和 LB 造成负面影响。甘蔗的 O3 敏感性可能与其高 gsto（~535 mmol H2O m-2 s-1）有关。由于甘蔗适应炎热的气候条件，当当前最低气温（Tmin）低于~14°C且前一天夜间最低气温（Tnmin）低于~7.5°C时，gsto受到限制。在估计 O3 对生物量损失的影响方面，基于通量的指数 (PODy) 的表现优于基于暴露的指数。我们建议 y 阈值为 2 nmol m-2 s-1，以结合 O3 对 AGB 和 SB 的影响以及 1 nmol m-2 s-1 对 LB 的影响。为了使这两种甘蔗基因型的生长减少不超过 4%，我们推荐以下临界水平：AGB 为 1.09 和 1.04 mmol m-2 POD2，SB 为 0.91 和 0.96 mmol m-2 POD2，以及 3.00 和 2.36分别为 IACSP95-5000 和 IACSP94-2094 LB 的 mmol m-2 POD1。