Examining cassava's potential to enhance food security under climate change

Authors: Rosenthal, David; Ort, Donald

Submitted to: Tropical Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2011
Publication Date: 3/1/2012
Citation: Rosenthal, D.M., Ort, D.R. 2012. Examining cassava's potential to enhance food security under climate change. Tropical Plant Biology. 5(1):30-38.

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 in the work reported that cassava photosynthesis tuber yield responded dramatically when grown in an atmosphere containing the amount of carbon dioxide expected for the middle of this century. Furthermore, the amount of toxic cyanide compounds in the tuber decreased.

Technical Abstract: Recent advances in the biofortification of cassava, a substantial yield gap and cassava's potential for increased productivity and its inherent potential to respond positively to globally increasing CO2 are synergistic and encouraging in an otherwise bleak global view of the future of food security in the developing world. It is shown that plants with large carbohydrate sinks such as cassava, potato and even sugar beet have significant increases in tuber mass at elevated CO2. The potential stimulation of yields by elevated CO2 for tuber crops such as cassava, yams and potatoes is under appreciated. Tuber crops have the potential for a much higher ratio of edible to non-edible components (i.e. harvest index) than above ground grain and bean crops such as rice, wheat, maize or soybean. Second, unlike above ground crops, tubers require no structural support when accumulating additional photosynthate. Third, due to their large capacities to store carbohydrates, tubers are inherently strong photosynthate sinks, so tuber crops are better adapted to respond to the stimulatory effect of increasing [CO2]. Therefore, as global atmospheric [CO2] continues to rise, so will the harvest index of tuber crops. In contrast, the harvest index of above ground crops decreases at elevated CO2.