Ozone effects in coffee (Coffea arabica L.) plants: Cultivar-specific responses and risk assessment

The environmental sustainability of agricultural production faces critical challenges due to climate change, with tropospheric ozone (O 3 ) being a significant concern. This study investigates the dose-response (DR) relationship between O 3 exposure and leaf biomass (LB, as a proxy of coffee production) reduction in three coffee cultivars ( Coffea arabica L. cv. Geisha, IAC99, and IAC62) using both exposure- (AOT40) and flux-based (POD Y ) indices. Experiments were conducted in a Free-Air Controlled Exposure (FACE), where plants were exposed to ambient air (AA), 1.5×AA, and 2.0×AA O 3 levels. The study reports the O 3 visible foliar injury (O 3 _VFI) on C. arabica leaves for the first time. It also reveals that O 3 significantly reduced total LB in the Geisha and IAC62 cultivars compared to the less affected IAC99. The stomatal conductance model was parametrized to estimate stomatal O 3 uptake and understand each cultivar's physiological response to O 3 stress. The Geisha and IAC62 cultivars exhibited higher stomatal O 3 uptake due to relatively high maximum stomatal conductance ( g max ) values compared to IAC99, leading to greater biomass loss under elevated O 3 conditions. The DR analysis identified POD 1.5 as the most appropriate index for assessing critical O 3 levels (CLs) for LB losses. Linear regression was suitable for representing the DR relationships, and the O 3 CL for a 4% and 10% LB reduction was estimated at 0.29 and 0.73 mmol m –2 POD 1.5 , respectively. These findings underscore the necessity of cultivar-specific studies for accurate O 3 risk assessment and management in coffee production. • First report of ozone-induced visible foliar injury (O 3 _VFI) in Coffea arabica. • Cultivar-specific ozone sensitivity was identified, with Geisha and IAC62 more affected than IAC99. • Stomatal conductance model parametrized to estimate O 3 uptake and biomass loss. • The Phototoxic Ozone Dose (POD 1.5 ) index was determined as the best metric for assessing coffee ozone risk.