Submitted to: Global Change Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/16/2012
Publication Date: 8/1/2012
Citation: Rosenthal, D.M., Slattery, R.A., Miller, R.E., Grennan, A.K., Gleadow, R.M., Cavagnaro, T.R., Fauquet, C.M., Ort, D.R. 2012. Cassava about-FACE: Greater than expected yield stimulation of cassava (Manihot esculenta) by future CO2 levels. Global Change Biology. 18:2661-2675. Interpretive Summary: World wide approximately 925 million people are undernourished and almost 90 % of these people live in Sub-Saharan Africa, Asia and the Pacific. Sub-Saharan Africa in particular, continues to have the highest proportion of chronically hungry where 1 in 3 individuals (ca. 240 million) are undernourished in terms of both food quantity and nutrition. The threat of substantial changes in climate raises concerns about future capacity to sustain even current levels of food security because climate change will impact food security most severely in regions where undernourishment is already problematic. Estimates of future climate change impacts on crops vary widely, particularly in Africa, due in part to a lack of agricultural and meteorological data. To more accurately predict future climate change impacts on food security we must first precisely assess the impact of climate change drivers on crops of food insecure regions. People within the poorest populations depend disproportionately on cassava tubers for food and it is shown that cassava fresh yield increased more than 115 ± 32% when grown under fully open air CO2 fumigation: more than twice the increase that was expected.
Technical Abstract: The potential for tuber crops such as cassava, yams and potatoes to enhance food security in the future is underestimated. In tuber crops there is the potential for a much higher ratio of edible to non-edible components than in above ground grain and bean crops such as rice, wheat, maize or soybean. These tubers due to their large capacities to store carbohydrates are inherently strong photosynthate "sinks" implying that tuber crops should be better adapted to respond to the stimulatory effect of increasing atmospheric [CO2]. It follows that, as global atmospheric [CO2] continues to rise, so will the yield of tuber crops. People within the poorest populations depend disproportionately on cassava and other tropical tubers for food and as a cash crop. Thus, in the future, enhanced productivity of tuber crops should work to benefit those who need it most. Here we show much greater than expected increases in productivity and yield of the starchy cassava tuber when grown in the field at atmospheric [CO2] expected by the middle of this century. As the most important crop in terms of caloric intake for many undernourished populations, stimulation of cassava yields in a future elevated [CO2] world will help to enhance food yields and security in the developing world.