Elevated CO2 Stimulates the Growth of Sunflower Plants

Paper Reviewed
Gong, X.Y., Schäufele, R., Lehmeier, C.A., Tcherkez, G. and Schnyder, H. 2017. Atmospheric CO2 mole fraction affects stand-scale carbon use efficiency of sunflower by stimulating respiration in light. Plant, Cell and Environment 40: 401-412.

As one of the top 35 crops in terms of global food production, it is important to understand how sunflower (Helianthus annus) plants will respond to increases in the air’s CO2 content. The latest study to do just that comes from Gong et al. (2017), who grew sunflower seeds (cv Sanluca) in plastic pots in controlled environment chambers under CO2 concentrations of 200 (low treatment) or 1000 ppm (high treatment) for a period of 42 days.

At the end of the experiment, Gong et al. report that elevated CO2 increased plant dry mass (g per plant) by 52 percent and plant photosynthesis by 91 percent. In addition, the aerial fertilization effect of elevated CO2 led to increases in net and gross primary productivity of 77 and 90 percent, respectively (see figure below). Furthermore, the authors report that stomatal conductance “showed a clear reduction, and intrinsic water use efficiency showed a clear increase with CO2” as well.

In light of the above, it would appear that, in the future, sunflower plants (and the farmers who grow them) will reap the growth-enhancing and water-saving benefits provided by rising levels of atmospheric CO2.

Figure 1. Net primary productivity (NPP, left panel) and gross primary productivity (GPP, right panel) of sunflower stands growing at either low (200 ppm) or high (1000 ppm) CO2. Adapted from Gong et al. (2017).

This article appeared on the CO2 Science website at http://www.co2science.org/articles/V20/jun/a7.php