Rising ozone pollution as a threat to wheat yields in India: insights from a concentration-based approach

Abstract

Rising levels of surface ozone (O3) in the arable ecosystem have emerged as a serious threat to food security by reducing the yield of major food grains, yet long-term, stage-specific assessments of O3 exposure and yield loss for wheat crop in India remain limited. Here, we present a comprehensive analysis of potential ozone-induced losses in wheat yield and production across India for the past two decades (2005–2021) using a high-resolution surface O3 data and the concentration-based Accumulated Ozone above a Threshold of 40 (AOT40) method. Our analysis reveals a substantial increase in relative yield loss (RYL) of wheat from 2005 to 2021 (25.2–35.3 %), resulting in an annual wheat production loss (WPL) of 21 ± 11.48 million tonnes (Mt) in 2005, rising to 48.6 ± 11.48 Mt by 2020. Critical reproductive stages of wheat, such as anthesis and grain filling, consistently experience AOT40 exposures exceeding the safe limit of 3000 ppb.h for crops, particularly across the Indo-Gangetic Plain (IGP). Prolonged and intense O3 exposure during these sensitive phenological stages exacerbates yield loss and underscores the vulnerability of wheat in India relative to other major wheat producing regions. To safeguard national food security amid climate change, rising air pollution and growing population, future efforts must prioritise long-term air quality and crop monitoring, crop-specific ozone tolerance studies and integrated mitigation strategies linking agriculture and air quality policies.