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 (O3) being a significant concern. This study investigates the dose-response (DR) relationship between O3 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 (PODY) 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 O3 levels. The study reports the O3 visible foliar injury (O3_VFI) on C. arabica leaves for the first time. It also reveals that O3 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 O3 uptake and understand each cultivar's physiological response to O3 stress. The Geisha and IAC62 cultivars exhibited higher stomatal O3 uptake due to relatively high maximum stomatal conductance (gmax) values compared to IAC99, leading to greater biomass loss under elevated O3 conditions. The DR analysis identified POD1.5 as the most appropriate index for assessing critical O3 levels (CLs) for LB losses. Linear regression was suitable for representing the DR relationships, and the O3 CL for a 4 % and 10 % LB reduction was estimated at 0.29 and 0.73 mmol m−2 POD1.5, respectively. These findings underscore the necessity of cultivar-specific studies for accurate O3 risk assessment and management in coffee production.