Response of Soybeans to a Carbon Dioxide‐Enriched Atmosphere1

Abstract
Two soybean varieties were exposed to 350 and 1350 ppm CO2 from seedling to maturity in Mylar chambers in the greenhouse. There was a marked increase in plant growth in the CO2 atmosphere at a concentration of 1350 ppm. Seed yields were increased 57% in the variety ‘Hark’ and 40% in the variety ‘Chippewa‐64’. The increase in seed yield was primarily due to an increase in the number of pods per plant. Many of the new pods were born on the longer branches in the CO2 enriched atmosphere.