Yield of wheat across a subambient carbon dioxide gradient

Authors

Herman S. Mayeux, USDA-ARS Grassland, Soil and Water Research Laboratory
Hyrum B. Johnson, USDA-ARS Grassland, Soil and Water Research Laboratory
H. Wayne Polley, USDA-ARS Grassland, Soil and Water Research LaboratoryFollow
Stephen R. Malone, University of West Alabama

Date of this Version

1997

Comments

Published in Global Change Biology (1997) 3, 269–278.

Abstract

Yields and yield components of two cultivars of day-neutral spring wheat (Triticum aestivum L.) were assessed along a gradient of daytime carbon dioxide (CO₂) concentrations from about 200 to near 350 µmol CO₂ (mol air)^–1 in a 38 m-long controlled environment chamber. The range in CO₂ concentration studied approximates that of Earth’s atmosphere since the last ice age. This 75% rise in CO₂ concentration increased grain yields more than 200% under well-watered conditions and by 80–150% when wheat was grown without additions of water during the last half of the 100-day growing season. The 27% increase in CO₂ from the pre-industrial level of 150 years ago (275 µmol mol^–1) to near the current concentration (350 µmol mol^–1) increased grain yields of ‘Yaqui 54’ and ‘Seri M82’ spring wheats by 55% and 53%, respectively, under well-watered conditions. Yield increased because of greater numbers of grains per spike, rather than heavier grains or numbers of spikes per plant. Water use increased little with CO₂ concentration, resulting in improved water use efficiency as CO₂ rose. Data suggest that rising CO₂ concentration contributed to the substantial increase in average wheat yields in the U.S. during recent decades.