Evaluation of the effects of elevated CO 2 concentrations on the growth of cassava storage roots by destructive harvests and ground penetrating radar scanning approaches.

Cassava (Manihot esculenta Crantz) production will need to be improved to meet future food demands in Sub-Saharan Africa. The selection of high-yielding cassava cultivars requires a better understanding of storage root development. Additionally, since future production will happen under increasing atmospheric CO concentrations ([CO ]), cultivar selection should include responsiveness to elevated [CO ]. Five farmer-preferred African cassava cultivars were grown for three and a half months in a Free Air CO Enrichment experiment in central Illinois. Compared to ambient [CO ] (~400 ppm), cassava storage roots grown under elevated [CO ] (~600 ppm) had a higher biomass with some cultivars having lower storage root water content. The elevated [CO ] stimulation in storage root biomass ranged from 33% to 86% across the five cultivars tested documenting the importance of this trait in developing new cultivars. In addition to the destructive harvests to obtain storage root parameters, we explored ground penetrating radar as a nondestructive method to determine storage root growth across the growing season.