Elevated atmospheric [CO2 ] can dramatically increase wheat yields in semi-arid environments and buffer against heat...

Area of Science:

• Agricultural Science
• Climate Change Biology
• Plant Physiology

Background:

• Rising atmospheric carbon dioxide (CO2) concentrations pose a significant threat to global wheat production.
• Field-level data on wheat responses to elevated CO2 (e[CO2]) in Mediterranean-type dryland environments, particularly those experiencing terminal drought and heat waves, are limited.

Purpose of the Study:

• To investigate the impact of e[CO2] on wheat (Triticum aestivum) growth and yield in semi-arid Australian dryland conditions.
• To compare wheat responses under ambient and e[CO2] (550 μmol mol⁻¹) at field scale, considering environmental variables.

Main Methods:

• Utilized the Australian Grains Free Air CO2 Enrichment (FACE) facility over three years at two dryland sites (Horsham and Walpeup).
• Implemented experimental treatments including two cultivars, two sowing times, and two irrigation regimes (rainfed and supplemental irrigation).
• Analyzed yield, grain quality parameters, and physiological responses under ambient (~370 μmol mol⁻¹) and e[CO2] conditions.

Main Results:

• Mean yield stimulation from e[CO2] was 24% at Horsham and 53% at Walpeup, with some treatments exceeding 70%.
• Supplemental irrigation significantly enhanced e[CO2] yield response (37% at Horsham) compared to rainfed conditions (13%), indicating water limitation.
• e[CO2] ameliorated heat wave impacts, reducing screenings and increasing kernel size, with greatest yield increases under late sowing and heat stress when water was available.

Conclusions:

• Wheat yield responses to e[CO2] in dryland Mediterranean environments are substantial and depend critically on water availability and temperature timing.
• The findings underscore the importance of field-level research for understanding crop adaptation mechanisms to climate change.
• Cultivar differences in response to e[CO2] were not significant under the studied conditions.