Assessing the effects of early and timely sowing on wheat cultivar HD 2967 under current and future tropospheric ozone scenarios

• Published in: Environmental and experimental botany 2024-12, Vol.228, p.106018, Article 106018
• Main Authors: Ghosh, Annesha, Pandey, Bhanu, Agrawal, Madhoolika, Agrawal, S.B.
• Format: Article
• Language: English
• Subjects: Antioxidants; Early sowing; Gas-exchange; Growth; Productivity
• ISSN: 0098-8472
• DOI: 10.1016/j.envexpbot.2024.106018

This study investigates the impact of elevated ozone (eO3) levels on the growth and yield of the wheat cultivar HD 2967 under different sowing dates in open-top chambers. Wheat was sown early on November 1st and timely on November 20th, 2017, under ambient and elevated O3 (ambient + 20 ppb), resulting in four treatment groups: AT (ambient + timely), ET (elevated + timely), AE (ambient + early), and EE (elevated + early). Results showed significant reductions in morphological traits and gas-exchange parameters, including photosynthetic rate, stomatal conductance, and water use efficiency under eO3. The most notable decreases were observed 40 days after germination (DAG) compared to 80 DAG. Interestingly, while a higher percentage reduction was observed under ET at 80 DAG, a reversal in the trend of percentage reduction between the two stages was noted, suggesting a dynamic response of the wheat cultivar to stress across the growth stage. However, compared with ET's results, early sowing mitigated these negative effects under a futuristic O3 level scenario, showing no significant impact on grain yield and productivity factors. This resilience is attributed to the extended growth period, enhancing photosynthesis and biomass accumulation while avoiding high eO3 concentrations during critical reproductive stages. Furthermore, a trade-off in ET plants suggests resources are allocated towards defense (enzymatic and non-enzymatic antioxidants) at the expense of growth, while EE conditions favor growth at later stages, maintaining reproductive fitness despite eO3 levels. Under conventional timely sowing, wheat may suffer yield declines of up to 30 % amidst rising eO3 levels. Early sowing emerges as a proactive strategy to maintain wheat productivity under increasing O3 stress. Future studies should explore the effectiveness of early sowing across multiple wheat cultivars and climatic conditions to inform sustainable agricultural practices in high O3 areas. [Display omitted] •Early sowing mitigates adverse effects of eO3 on wheat biomass and photosynthesis.•Extended growth period under early sowing compensates for grain yield loss despite increased O3.•Conventional timely sowing risks significant wheat yield decline under projected higher O3 levels.•Trade-off observed between growth and defense mechanisms under timely sowing and eO3 conditions.•Early sowing can be akey strategy to safeguard wheat productivity in the IGP region against escalating O3 concentrations.