Ozone Effects on the Quality of Swiss Chard. Peri-Urban Crops a Case Study

The objective of this research was to evaluate the sensitivity of leafy crops to ozone levels and the possible effects of this pollutant in the peri-urban crops.

Ground level ozone is widely recognized as the most damaging air pollutant to vegetation due to its phytotoxicity and prevalence at high concentrations over rural/agricultural regions. Also, 90% of the urban population is exposed to ozone exceeding the WHO guideline (EEA, 2017). Developing peri-urban agriculture is regarded as one of the key strategies to attend the high food demands, which helps to reduce the environmental impacts of the food system. However, the threat of the peri-urban agriculture is the air quality and the effects in the food security. Ozone causes a wide variety of damage in leafy crops including visible injury, reduction in photosynthesis, alterations to carbon allocation, and reduction in yield quantity and quality.

Ozone levels on the peri-urban farm of central Spain have exceeded the critical level for protection of vegetation during the summer months. Two studies were developed to evaluate the effects of ozone on a local variety of leafy crops. An open-top chamber experiment of ozone has been used to gain insights of response to this variety of ozone. Different physiological parameters were measured to identify traits related to the sensitivity/ tolerant to ozone. At the same time, to find out the extent of the problem, a bioindication vegetable garden was cultivated in this area, where the plants were followed-up meticulously.

The results of the fumigation study showed a moderate reduction in commercial production, changes in pigment concentrations, and alterations in nutritional quality of this variety. Also, the ozone reduces the gas exchange rate, with a higher reduction in stomatal conductance than photosynthesis. We didn't identify significant alteration of Swiss chard varieties in the bioindication vegetable garden. The different response to air pollution could be related to the environmental conditions.