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Brewster C, Fenner N, Hayes F. Chronic ozone exposure affects nitrogen remobilization in wheat at key growth stages. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 908:168288. [PMID: 37924890 DOI: 10.1016/j.scitotenv.2023.168288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 10/27/2023] [Accepted: 10/31/2023] [Indexed: 11/06/2023]
Abstract
The interaction between nitrogen storage and translocation, senescence, and late phase photosynthesis is critical to the post-anthesis grain fill period in wheat, but ozone's effect on nitrogen dynamics within the wheat plant is not well understood. This study used solardomes to expose a widely grown elite spring wheat cultivar, cv. Skyfall, to four levels of ozone (30 ppb, 45 ppb, 70 ppb, 85 ppb) for 11 weeks, with two levels of nitrogen fertilization, 140 kg ha-1 and 160 kg ha-1, the higher rate including an additional 20 kg N ha-1 at anthesis. Chronic ozone exposure triggered earlier senescence in the 4th, 3rd and 2nd leaves but not the flag leaf, with a similar pattern of reduced chlorophyll content in the lower, older leaf cohorts, which started before senescence became visible. At anthesis there was no evidence of any effect of ozone on nitrogen storage in upper plant parts. However, high ozone increased levels of residual nitrogen found within plant parts at harvest, with concomitant reductions in C:N ratios and Nitrogen Remobilization Efficiency. Extra nitrogen fertilization applied at anthesis appeared to ameliorate the effect of ozone on nitrogen content and nitrogen translocation. The application of 15N ammonium nitrate at anthesis confirmed that the majority of post-anthesis nitrogen uptake had been translocated to the ear/grain by harvest, with no effect of ozone on the translocation of nitrogen around the plant. These data can inform future modelling of ozone's effect on nitrogen dynamics and global wheat yields.
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Affiliation(s)
- Clare Brewster
- UK Centre for Ecology & Hydrology, Environment Centre Wales, Bangor, Wales, UK; Bangor University, School of Natural Sciences, Bangor, Wales, UK.
| | - Nathalie Fenner
- Bangor University, School of Natural Sciences, Bangor, Wales, UK.
| | - Felicity Hayes
- UK Centre for Ecology & Hydrology, Environment Centre Wales, Bangor, Wales, UK.
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The Influence of Ozone on Net Ecosystem Production of a Ryegrass–Clover Mixture under Field Conditions. ATMOSPHERE 2021. [DOI: 10.3390/atmos12121629] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In order to understand the effect of phytotoxic tropospheric ozone (O3) on terrestrial vegetation, we quantified the impact of current O3 concentration ([O3]) on net ecosystem production (NEP) when compared to the conditions of the pre-industrial era. We compared and tested linear mixed-effects models based on [O3] and stomatal O3 flux (Fsto). The managed ryegrass–clover (Lolium perenne and Trifolium pratense) mixture was grown on arable land in the Czech Republic, Central Europe. Values of [O3] and Fsto were measured and calculated based on resistance analogy, respectively, while NEP was calculated from eddy covariance CO2 fluxes. We found the Fsto-based model more precise when compared to measured NEP. High Fsto was found even at low [O3], while broad summer maximum of [O3] was not necessarily followed by significant NEP decline, due to low soil water content leading to a low stomatal conductivity and Fsto. Comparing to low pre-industrial O3 conditions, current levels of O3 resulted in the reduction of cumulative NEP over the entire growing season, up to 29.7 and 13.5% when the [O3]-based and Fsto-based model was applied, respectively. During the growing season, an O3-induced reduction of NEP ranged between 13.1% in May and 26.2% in July when compared to pre-industrial Fsto levels. Looking to the future, high [O3] and Fsto may lead to the reduction of current NEP by approximately 13.3% on average during the growing season, but may increase by up to 61–86.6% in autumn, indicating further O3-induced acceleration of the senescence. These findings indicate the importance of Fsto and its inclusion into the models estimating O3 effects on terrestrial vegetation. The interaction between environmental factors and stomatal conductance is therefore discussed in detail.
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Dai L, Hayes F, Sharps K, Harmens H, Mills G. Nitrogen availability does not affect ozone flux-effect relationships for biomass in birch (Betula pendula) saplings. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 660:1038-1046. [PMID: 30743901 DOI: 10.1016/j.scitotenv.2019.01.092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/07/2019] [Accepted: 01/09/2019] [Indexed: 06/09/2023]
Abstract
To investigate whether nitrogen (N) load affects the ozone (O3) stomatal flux-effect relationship for birch biomass, three-year old birch saplings were exposed to seven different O3 profiles (24 h mean of 35-66 ppb) and four different N loads (10, 30, 50 and 70 kg ha-1 yr-1) in precision-controlled hemispherical glasshouses (solardomes) in 2012 and 2013. Stomatal conductance (gs) under optimal growth conditions was stimulated by enhanced N supply but was not significantly affected by enhanced O3 exposure. Birch root, woody (stem + branches) and total biomass (root + woody) were not affected by the Phytotoxic Ozone Dose (POD1SPEC) after two seasons of O3 exposure, and enhanced N supply stimulated biomass production independent of POD1SPEC (i.e. there were no POD1SPEC × N interactions). There was a strong linear relationship between the stem cross-sectional area and tree biomass at the end of the experiment, which was not affected by O3 exposure or N load. Enhanced N supply stimulated the stem cross-sectional area at the end of season 2, but not at the end of season 1, which suggests a time lag before tree biomass responded to enhanced N supply. There was no significant effect of POD1SPEC on stem cross-sectional area after either the first or second growing season of the experiment. Contrasting results reported in the literature on the interactive impacts of O3 and N load on tree physiology and growth are likely due to species-specific responses, different duration of the experiments and/or a limitation of the number of O3 and N levels tested.
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Affiliation(s)
- Lulu Dai
- Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, United Kingdom; State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, Haidian District, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Shijingshan District, Beijing 100049, China
| | - Felicity Hayes
- Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, United Kingdom.
| | - Katrina Sharps
- Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, United Kingdom
| | - Harry Harmens
- Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, United Kingdom
| | - Gina Mills
- Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, United Kingdom
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Osborne S, Pandey D, Mills G, Hayes F, Harmens H, Gillies D, Büker P, Emberson L. New Insights into Leaf Physiological Responses to Ozone for Use in Crop Modelling. PLANTS (BASEL, SWITZERLAND) 2019; 8:E84. [PMID: 30939811 PMCID: PMC6524376 DOI: 10.3390/plants8040084] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/20/2019] [Accepted: 03/23/2019] [Indexed: 01/03/2023]
Abstract
Estimating food production under future air pollution and climate conditions in scenario analysis depends on accurately modelling ozone (O₃) effects on yield. This study tests several assumptions that form part of published approaches for modelling O₃ effects on photosynthesis and leaf duration against experimental data. In 2015 and 2016, two wheat cultivars were exposed in eight hemispherical glasshouses to O₃ ranging from 22 to 57 ppb (24 h mean), with profiles ranging from raised background to high peak treatments. The stomatal O₃ flux (Phytotoxic Ozone Dose, POD) to leaves was simulated using a multiplicative stomatal conductance model. Leaf senescence occurred earlier as average POD increased according to a linear relationship, and the two cultivars showed very different senescence responses. Negative effects of O₃ on photosynthesis were only observed alongside O₃-induced leaf senescence, suggesting that O₃ does not impair photosynthesis in un-senesced flag leaves at the realistic O₃ concentrations applied here. Accelerated senescence is therefore likely to be the dominant O₃ effect influencing yield in most agricultural environments. POD was better than 24 h mean concentration and AOT40 (accumulated O₃ exceeding 40 ppb, daylight hours) at predicting physiological response to O₃, and flux also accounted for the difference in exposure resulting from peak and high background treatments.
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Affiliation(s)
- Stephanie Osborne
- Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK.
- Stockholm Environment Institute, Environment Department, University of York, York YO10 5NG, UK.
| | - Divya Pandey
- Stockholm Environment Institute, Environment Department, University of York, York YO10 5NG, UK.
| | - Gina Mills
- Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK.
| | - Felicity Hayes
- Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK.
| | - Harry Harmens
- Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK.
| | - David Gillies
- Stockholm Environment Institute, Environment Department, University of York, York YO10 5NG, UK.
| | - Patrick Büker
- Stockholm Environment Institute, Environment Department, University of York, York YO10 5NG, UK.
| | - Lisa Emberson
- Stockholm Environment Institute, Environment Department, University of York, York YO10 5NG, UK.
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Harmens H, Hayes F, Sharps K, Mills G, Calatayud V. Leaf traits and photosynthetic responses of Betula pendula saplings to a range of ground-level ozone concentrations at a range of nitrogen loads. JOURNAL OF PLANT PHYSIOLOGY 2017; 211:42-52. [PMID: 28152417 DOI: 10.1016/j.jplph.2017.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 06/06/2023]
Abstract
Ground-level ozone (O3) concentrations and atmospheric nitrogen (N) deposition rates have increased strongly since the 1950s. Rising ground-level O3 concentrations and atmospheric N deposition both affect plant physiology and growth, however, impacts have often been studied in isolation rather than in combination. In addition, studies are often limited to a control treatment and one or two elevated levels of ozone and/or nitrogen supply. In the current study, three-year old Betula pendula saplings were exposed to seven different O3 profiles (24h mean O3 concentration of 36-68ppb in 2013, with peaks up to an average of 105ppb) in precision-controlled hemispherical glasshouses (solardomes) and four different N loads (10, 30, 50 or 70kgNha-1y-1) in 2012 and 2013. Here we report on the effects of enhanced O3 concentrations and N load on leaf traits and gas exchange in leaves of varying age and developmental stage in 2013. The response of leaf traits to O3 (but not N) vary with leaf developmental stage. For example, elevated O3 did not affect the chlorophyll content of the youngest fully expanded leaf, but it reduced the chlorophyll content and photosynthetic parameters in aging leaves, relatively more so later than earlier in the growing season. Elevated O3 enhanced the N content of senesced leaves prior to leaf fall, potentially affecting subsequent N cycling in the soil. Enhanced N generally stimulated the chlorophyll content and photosynthetic capacity. Whilst elevated O3 reduced the light-saturated rate of photosynthesis (Asat) in aging leaves, it did not affect stomatal conductance (gs). This suggests that photosynthesis and gs are not closely coupled at elevated O3 under-light saturating conditions. We did not observe any interactions between O3 and N regarding photosynthetic parameters (Vc,max, Jmax, Asat), chlorophyll content, gs, N content in senesced leaves and leaf number. Hence, the sensitivity of these leaf traits to O3 in young silver birch trees is neither reduced nor enhanced by N load.
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Affiliation(s)
- Harry Harmens
- Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
| | - Felicity Hayes
- Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
| | - Katrina Sharps
- Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
| | - Gina Mills
- Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
| | - Vicent Calatayud
- Fundación CEAM, c/Charles R. Darwin 14, Parque Tecnológico, 46980 Paterna, Valencia, Spain.
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