Wheat yield response to elevated O₃ concentrations differs between the world's major producing regions.

Area of Science:

• Environmental Science
• Agricultural Science
• Plant Science

Background:

• Ground-level ozone (O3) concentrations are increasing globally, particularly in Asia.
• Wheat is highly sensitive to ozone, posing a significant threat to global food security.
• Asia produces a substantial portion of the world's wheat.

Purpose of the Study:

• To estimate the relationship between ozone exposure (AOT40) and relative wheat yield across major producing regions.
• To identify regional differences in wheat yield loss due to ozone.
• To investigate factors contributing to these regional variations.

Main Methods:

• Utilized data from ozone elevation experiments in China, India, Europe, and North America.
• Calculated ozone dose using AOT40 (accumulated daytime O3 concentrations above 40 ppb for 90 days).
• Analyzed yield loss components (grain weight, grain number) and considered cultivar age and regional climate factors.

Main Results:

• Wheat yield loss due to ozone was greatest in China, followed by India, Europe, and North America.
• In China, Europe, and North America, reduced grain weight was the primary cause of yield loss.
• In India, reduced grain number contributed more significantly to yield loss than grain weight reduction.

Conclusions:

• Regional differences in ozone-induced wheat yield loss are substantial and influenced by factors beyond ozone concentration.
• Cultivar age plays a critical role, with older cultivars in North America showing less sensitivity.
• Accurate quantification of ozone-induced yield loss requires region-specific dose-response models incorporating climate and cultivar variations.