Background
The authors note that (1) "rice is unequivocally one of the most important food crops that feed the largest proportion of the world's population," that (2) "the demand for rice production will continue to increase in the coming decades, especially in the major rice-consuming countries of Asia, Africa and Latin America," and that (3) "accurate predictions of rice yield and of the ability of rice crops to adapt to high CO2 environments are therefore crucial for understanding the impact of climate change on the future food supply." Indeed, they forcefully declare -- and rightly so -- that "there is a pressing need to identify genotypes which could optimize harvestable yield as atmospheric CO2 increases," which is precisely what they set out to do.

What was done
In a standard paddy culture FACE experiment conducted at Yangzhou, Jiangsu, China, over the period 2004-2006, Yang et al. grew a two-line inter-subspecific hybrid rice variety (Liangyoupeijiu) at ambient and elevated atmospheric CO2 concentrations of 376 and 568 ppm, respectively, at two levels of field nitrogen (N) application: low N (12.5 g N m^-2) and high N (25 g N m^-2), measuring numerous aspects of crop growth, development, and final yield production in the process.

What was learned
The ultimate "bottom-line" finding of the eight Chinese scientists was that the 51% increase in atmospheric CO2 concentration employed in their study increased the final grain yield of the low N rice crop by 28% and that of the high N rice crop by 32%. As a result, and "compared with the two prior rice FACE experiments (Kim et al., 2003; Yang et al., 2006)," they say that "hybrid rice appears to profit much more from CO2 enrichment than inbred rice cultivars (c. +13%)."

What it means
It is little wonder that Yang et al. describe Liangyoupeijiu as "one of the most popular 'super' hybrid rice varieties in China (Peng et al., 2004)," and it appears that it will become ever more "super" as the air's CO2 content continues to rise, helping China to lead the way in future food production.

References
Kim, H.Y., Lieffering, M., Kobayashi, K., Okada, M., Mitchell, M.W. and Gumpertz, M. 2003. Effects of free-air CO2 enrichment and nitrogen supply on the yield of temperate paddy rice crops. Field Crops Research 83: 261-170.

Peng, S., Laza, R.C., Visperas, R.M., Khush, G.S., Virk, P. and Zhu, D. 2004. Rice: Progress in breaking the yield ceiling. In: New Directions for a Diverse Planet: Proceedings of the Fourth International Crop Science Congress, 26 Sep-1 Oct 2004, Brisbane, Australia.

Yang, L.X., Huang, J.Y., Yang, H.J., Zhu, J.G., Liu, H.J., Dong, G.C., Liu, G., Han, Y. and Wang, Y.L. 2006. The impact of free-air CO2 enrichment (FACE) and N supply on yield formation of rice crops with large panicle. Field Crops Research 98: 141-150.