Chronic tropospheric ozone exposure reduces seed yield and quality in spring and winter oilseed rape

Oilseed rape (Brassica napus L.) is cultivated worldwide, producing 11.5% of global oilseeds at an economic value 38 billion USD in 2020. It sensitive to phytotoxic damage from exposure tropospheric ozone (O3), a major air pollutant, which disrupts plant physiological processes and thus decreases biomass accumulation. As background concentrations continue increase globally, we investigated the impact on seed oil yield shorter-lived spring (cv. Click) longer-lived winter Phoenix) oilseed cultivar levels (treatments with peaks 30, 55, 80, 110 ppbv) representative typical European conditions where these cultivars are common. Thousand Seed Weight (TSW), important measure final yield, decreased more Phoenix (40%) than Click (20%) increasing exposure. produced racemes many small seeds while fewer larger seeds. However, quality declined substantially Phoenix. The content Click's significantly increased exposure, less desirable components (moisture, chlorophyll, ash) increased. Scaled field-level, our findings imply substantial penalties for growers, potential losses 175–325 ha−1 500–665 under summer periods Europe. Decreased total would likely outweigh benefits any improvement animal cake (increased protein key micronutrients livestock feed). Neither sustained visible injury earlier growth stages, photosynthesis even high thereby making invisible threat. Our reduced quantity threaten production, but differences between may also offer opportunity breeders agronomists identify exploit variation tolerance rape.