Novel ozone flux metrics incorporating the detoxification process in the apoplast: An application to Chinese winter wheat

Rongjun Wu; Evgenios Agathokleous; Zhaozhong Feng

doi:10.1016/j.scitotenv.2020.144588

Novel ozone flux metrics incorporating the detoxification process in the apoplast: An application to Chinese winter wheat

Sci Total Environ. 2021 May 1:767:144588. doi: 10.1016/j.scitotenv.2020.144588. Epub 2021 Jan 2.

Authors

Rongjun Wu¹, Evgenios Agathokleous², Zhaozhong Feng³

Affiliations

¹ Key Laboratory of Agrometeorology of Jiangsu Province, School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, Jiangsu 210044, China. Electronic address: wurj@nuist.edu.cn.
² Key Laboratory of Agrometeorology of Jiangsu Province, School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, Jiangsu 210044, China. Electronic address: evgenios@nuist.edu.cn.
³ Key Laboratory of Agrometeorology of Jiangsu Province, School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, Jiangsu 210044, China. Electronic address: zhaozhong.feng@nuist.edu.cn.

PMID: 33429267
DOI: 10.1016/j.scitotenv.2020.144588

Abstract

A modified Ball-Berry-Leuning model of stomatal conductance was applied to data from fully open-air ozone (O₃)-enrichment experiments with winter wheat (Triticum aestivum L.). The O₃ fluxes reaching both surface of cell wall (F_cw) and plasmalemma (F_pl) were estimated considering apoplastic ascorbate, a major scavenger of O₃. The difference (D) between F_cw and F_pl was defined as detoxification capacity of O₃ by reaction with ascorbate in the leaf apoplast (ASC_apo). The accumulated stomatal O₃ flux above D nmol O₃ m^-2 s^-1 (AF_stD) and the accumulated F_pl (AF_pl) were calculated over the optimal integration period covering the whole reproductive development of wheat, and used to derive O₃AF_stD yield-response relationships in comparison with POD_Y (phytotoxic O₃ dose above a threshold of Y nmol m^-2 s^-1) and AOT40 (accumulated O₃ dose over a threshold of 40 ppb). There was a good agreement between the observed and modeled values of ASC_apo and stomatal conductance. AF_stD and AF_pl performed better than POD_Y and AOT40 in terms of R² and intercept. However, the AF_stD 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_pl. The average critical level (CL) of four cultivars for 5% grain-yield reduction was 1.53 mmol m^-2 using POD₆ and 2.81 mmol m^-2 using AF_stD, with the latter being well above the POD₆-derived value for European cultivars (1.3 mmol m^-2). The minimum hourly averaged O₃ concentration contributed to CLs was below 20 ppb according to AF_stD, a value that is lower than that suggested by POD₆ (≈27 ppb). O₃ flux-response relationships and CLs on the basis of quantified detoxification capacity shall facilitate the understanding of the different degrees of susceptibility to O₃ among species or cultivars, and improve the assessments of O₃ impacts on plants.

Keywords: Ascorbate; Detoxification capacity; Flux-response relationships; Ozone; Stomatal conductance; Wheat.

MeSH terms

Air Pollutants* / analysis
Air Pollutants* / toxicity
Benchmarking
China
Ozone* / analysis
Plant Leaves / chemistry
Triticum

Substances

Air Pollutants
Ozone