Effects of elevated CO2 on growth of the industrial sweet potato cultivar CX-1

Authors: Runion, George; Prior, Stephen - Steve; MONDAY, TYLER - Auburn University; RYAN-BOHAC, JANICE - Carenergy, Llc

Submitted to: Environment Control in Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2017
Publication Date: 4/1/2018
Citation: Runion, G.B., Prior, S.A., Monday, T., Ryan-Bohac, J. 2018. Effects of elevated CO2 on growth of the industrial sweet potato cultivar CX-1. Environment Control in Biology. 56(2):89-92. https://doi:10.2525/ecb.56.89.
DOI: https://doi.org/10.2525/ecb.56.89

Interpretive Summary: The level of carbon dioxide (CO2) in the Earth's atmosphere is rising and will have direct effects on plants. In general, most plants grown in high CO2 show increased growth and yield, as well as better plant water use efficiency (e.g., produce more biomass with less water). Sweet potatoes have been shown to be a good source for production of bioethanol. In fact, several varieties (called "industrial varieties") have recently been bred just for bioethanol production. However, the effects of elevated CO2 on these new, "industrial varieties" of sweet potato have not been studied. We grew sweet potato plants of the industrial variety CX-1 in open top field chambers using either normal air or air with added CO2 (about 67 % higher than normal) for one growing season. The higher CO2 increased growth of the CX-1 sweet potato plants. In particular, the yield of tubers (or potatoes) - which is the main yield component and the part used for making bioethanol - increased by 41 % compared with plants grown in normal air. These results show that the sweet potato “industrial variety” CX-1 can be a good source plant for bioethanol production and that the amount of bioethanol produced by this variety could become even greater as atmospheric CO2 continues to rise.

Technical Abstract: The rising concentration of atmospheric carbon dioxide (CO2) is known to directly affect plants, increasing growth, yield, and resource use efficiency. Further, it has been shown that sweet potatoes (Ipomoea batatas) represent a potential as a source of bioethanol production, particularly industrial varieties bred specifically for this purpose. However, the effects of elevated CO2 on these new, industrial varieties of sweet potato remain uninvestigated. We grew sweet potato plants of the industrial variety CX-1 in open top field chambers exposed to either ambient or elevated (ambient + 200 µmol mol-1 CO2) for one growing season and examined growth and allocation responses. Growth in elevated CO2 increased biomass production for variety CX-1. In particular, tuber dry weight increased by 40.9% compared with plants grown in ambient CO2. Fresh weight allocation to belowground plant organs (roots and tubers) was also increased under elevated CO2, but dry weight partitioning was unaffected. Aboveground (vines plus leaves) dry weight:fresh weight ratio was increased by elevated CO2, indicating possible alterations in tissue anatomy and/or chemistry. The industrial sweet potato CX-1 has potential as a source for bioethanol production and this potential could be enhanced as atmospheric CO2 continues to rise.