Elevated CO2 concentration effects on reproductive phenology and seed yield among soybean cultivars

Authors: Bunce, James

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2014
Publication Date: 1/1/2015
Citation: Bunce, J.A. 2015. Elevated CO2 concentration effects on reproductive phenology and seed yield among soybean cultivars. Crop Science. 55:339-343.

Interpretive Summary: The increase in seed yield caused by growth at elevated carbon dioxide concentrations varies greatly among varieties of soybean. Reasons for this variation are not known. This study found that the extension of the duration of vegetative growth caused by elevated carbon dioxide concentration was strongly linked to the increase in seed yield. This work will be of interest to scientists attempting to develop varieties of crops better adapted to rising atmospheric carbon dioxide concentrations.

Technical Abstract: Seed yield increases in soybeans caused by increased growth at elevated carbon dioxide concentrations primarily result from increased numbers of pods. However, reasons for differences among cultivars in the increases in pod number caused by elevated carbon dioxide are not clear. In experiments in controlled environment chambers cultivars varied in how much elevated carbon dioxide delayed the transition of the apical node of the main stem from vegetative to reproductive growth. The longer the delay in the transition, the more main stem and total nodes and pods were produced, increasing the relative stimulation of seed yield. A comparison of three indeterminate cultivars grown in free-air carbon dioxide enrichment systems in the field indicated that the time of the first open flower, and the rate of progression through reproductive stages was faster, slower, or unchanged by elevated carbon dioxide concentration in the three cultivars. However, independently from these effects on the rate of progression through the flowering stages, elevated carbon dioxide concentration also differentially affected the overall duration of vegetative growth, and the number of main stem and total nodes and pods produced. The extension of the duration of vegetative growth caused by elevated carbon dioxide was highly correlated with the relative seed yield increase in the field, as well as in the controlled environment chamber experiments.