DOI: 10.5285/66e73c38-5b85-44a1-818a-52189bdcffda
title: Sweet potato leaf stomatal conductance, leaf chlorophyll content, and tuber yield after exposure to three ozone concentrations in heated glasshouses, UK, 2019-2021

description: The data comprises physiological and yield measurements from an ozone (O3) exposure experiment, during which three varieties of sweet potato (Ipomoea batatas) were exposed to Low, Medium and High O3 treatments using heated dome shaped glasshouses (solardomes). The Erato orange variety was exposed to the three treatments from June to October 2019 and the Murasaki variety from June to October 2021. The Beauregard variety was grown on two occasions, with treatments from August to October 2020, and June to October 2021.
Measurements were taken of leaf stomatal conductance, leaf chlorophyll content index as well as the harvest (fresh) weight of tubers. All measurements were made by the corresponding author. The experiments were carried out in the UKCEH Bangor Air Pollution Facility. This work was carried out as part of the UK Centre for Ecology & Hydrology Long-Term Science Official Development Assistance ‘SUNRISE’ project.

Stomatal conductance was found to be significantly reduced in the elevated ozone treatments. Yield for the Erato orange and Murasaki varieties was reduced by ~40% and ~50% (Medium and High, respectively, vs Low) whereas Beauregard yield (2021) was reduced by 58% in both (the tubers for the Beauregard plants grown in 2020 were not fully formed). 
Sweet potato is a staple food crop grown in locations deemed to be at risk from O3 pollution (e.g. Sub-Saharan Africa), and this dataset adds much needed stomatal conductance and yield data of sweet potato grown under different O3 exposure conditions. This can be used to improve model predictions of O3 impacts on sweet potato, along with associated risk assessments.
description: Sweet potato plug plants (Thompson and Morgan) were each potted into 25 L tubs (35 x 37 cm) filled with John Innes No. 2 (J. Arthur Bowers, UK) compost and placed in heated (ambient +6℃) solardomes (3 m diameter and 2.1 m height) with controlled O3 exposure. Each solardome contained 4 replicate plants exposed to Low, Medium and High O3 treatments (daytime target maximums: 30 ppb, 80 ppb and 110 ppb, respectively). To represent the episodic nature of O3 pollution, for two days of the week all treatment domes received the Low O3 level. O3 concentrations were measured every 30 minutes (for 5 minutes) using two O3 analysers (API 400A Envirotech, UK and 49i Thermo Fisher Scientific, USA) of matched calibration. O3 delivery was controlled and recorded by LabVIEW software (version 2012, National Instruments). Air temperature, relative humidity and light was monitored inside the solardomes (Skye Instruments) and automatically recorded to the LabVIEW software as 30 minute mean values.

Leaf level stomatal conductance, temperature and light was recorded using a Delta-T AP4 porometer (calibrated before each measurement session to a curve error of ~10%). The chlorophyll content index of the same leaf was measured immediately afterwards using an Opti-Sciences CCM200 meter. The soil moisture status was measured using a Delta-T ML2 probe attached to a HH2 Moisture meter. Data was recorded onto field sheets and transferred to Excel sheets subsequently exported to comma separated value files for deposit into the EIDC.