Soybean yield and seed composition changes in response to increasing atmospheric CO<inf>2</inf> concentration in short-season Canada

Citation

Cober, E.R., Morrison, M.J. (2019). Soybean yield and seed composition changes in response to increasing atmospheric CO2 concentration in short-season Canada. Plants, [online] 8(8), http://dx.doi.org/10.3390/plants8080250

Plain language summary

Since 1993 we grew the same set of old to newer soybean cultivars to document yield improvement and changes to plant and seed characteristics due to plant breeding. Over this time, global atmospheric carbon dioxide concentration has increased 47 ppm. We analyzed this data to determine if there were changes in soybean seed yield, quality or development attributable to elevated atmospheric CO2 concentration (eCO2), temperature or precipitation. Over the 23 years we studied, there was a significant increase in atmospheric CO2 concentration but no change for in-season average maximum or minimum temperatures, or average in-season rainfall. Seed yield was increased significantly by eCO2, higher precipitation and higher minimum temperatures during flowering and podding. Yield decreased with higher minimum temperatures during vegetative growth and seed filling. Seed oil and also seed protein plus oil concentrations were both reduced with eCO2. Development has also changed with soybean spending less time in vegetative growth, while time to maturity remained constant. We also estimated genetic gain due to plant breeding each year. Over the 23 years of the study, genetic improvement rates decreased as [CO2] increased. Newer cultivars are not better adapted to eCO2 and soybean breeders may need to intentionally select for favourable responses to eCO2 in the future.

Abstract

From 1993, we have conducted trials with the same set of old to newer soybean cultivars to determine the impact of plant breeding on seed yield, physiological and agronomic characteristics, and seed composition. Since 1993, global atmospheric [CO2] increased by 47 ppm. The objective of our current analysis with this data set was to determine if there were changes in soybean seed yield, quality or phenology attributable to elevated atmospheric CO2 concentration (eCO2), temperature or precipitation. Additionally, we estimated genetic gain annually. Over 23 years, there was a significant increase in atmospheric [CO2] but not in-season average maximum or minimum temperatures, or average in-season precipitation. Seed yield was increased significantly by eCO2, higher precipitation and higher minimum temperatures during flowering and podding. Yield decreased with higher minimum temperatures during vegetative growth and seed filling. Seed oil and also seed protein plus oil concentrations were both reduced with eCO2. Phenology has also changed, with soybean cultivars spending less time in vegetative growth, while time to maturity remained constant. Over the 23 years of the study, genetic improvement rates decreased as [CO2] increased. Newer cultivars are not better adapted to eCO2 and soybean breeders may need to intentionally select for favourable responses to eCO2 in the future.

Publication date

2019-01-01