Ozone effects in high sugar grass pasture

The impacts of ozone on the growth and functioning of high-sugar ryegrass (HSG) pasture mesocosms was assessed in year 2013. Pasture mesocosms, containing perennial ryegrass (Lolium perenne L) and white clover (Trifolium repens L), were grown in the early spring and exposed to ozone in solardomes from late April 2013 to the end of September 2013. Ozone (30, 35, 40, 45, 52, 67 parts per billion (ppb) treatment means) had a large effect on the pasture mesocosms, including causing ozone-injury and reduced shoot biomass growth, reduced gas exchange and net primary productivity of pasture mesocosms, reduced nodulation and nitrogen fixation in clover, and negative impacts on forage quality. Flux-based dose-response relationships were constructed for biomass, N-fixation and forage quality parameters. In general, a good fit (r squared) may be found with below-ground variables, and new dose-response relationships developed may assist in the development of new critical levels for impacts of ozone on pasture vegetation. Effect of ozone on shoot biomass and injury rate may reduce over time as vegetation acclimates to high ozone levels. Data was first recording in the field in field notebooks, and was then transferred to electronic copies (MS Excel worksheets). Data was then exported as .csv files for ingestion into the Environmental Information Data Centre.