Background
The authors write that "mining and smelting, disposal of sewage sludge and use of cadmium (Cd) rich phosphate fertilizers have contaminated large areas throughout the world, causing an increase in the Cd content of the soil (Liu et al., 2007)," which they indicate is an unfortunate development because "cadmium is a non-essential element that negatively affects plant growth and development processes, such as respiration and photosynthesis (Vega et al., 2006), water and mineral uptake (Singh and Tewari, 2003), cell division (Fojtova et al., 2002) and cellular redox homoeostasis (Romero-Puertas et al., 2004)."

What was done
Perennial ryegrass (Lolium perenne) plants were grown from seed hydroponically in half-strength Hoagland solution for 3 days, which was followed by growth in full-strength Hoagland solution for 5 and 20 days and at a range of Cd concentrations ranging from 0 to 160 µmol/liter, while the five researchers monitored plant growth and development.

What was learned
Jia et al. report that regardless of Cd treatment, they found that "the Cd concentration was much lower under elevated CO2 than under ambient CO2," most likely due to the "fast growth triggered by elevated CO2," such that in their experiment "the dry biomass increased by 81.2% for shoots and 55.2% for roots under non-Cd stress, and an average of 99.1% for shoots and 68.5% for roots under Cd stress, respectively."

What it means
In the words of the five Chinese scientists, "these results indicate that under elevated CO2, L. perenne may be better protected against Cd stress with higher biomass, lower Cd concentration and better detoxification by phytochelatins." In addition, they state that "lower Cd concentration in plants under elevated CO2 may relieve the Cd toxicity to plants and reduce the risk of Cd transport in the food chain."

References
Fojtova, M., Fulneckova, J., Fajkus, J. and Kovarik, A. 2002. Recovery of tobacco cells from cadmium stress is accompanied by DNA repair and increased telomerase activity. Journal of Experimental Botany 53: 2151-2158.

Liu, Y.G., Wang, X., Zeng, G.M., Qu, D., Gu, J.J., Zhou, M. and Chai, L. 2007. Cadmium-induced oxidative stress and response of the ascorbate-glutathione cycle in Bechmeria nivea (L.), Gaud. Chemosphere 69: 99-107.

Romero-Puertas, M.C., Rodriguez-Serrano, M., Corpas, F.J. and delRio, L.A. 2004. Cadmium-induced subcellular accumulation of O^2.- and H2O2 in pea leaves. Plant, Cell and Environment 27: 1122-1134.

Singh, P.K. and Tewari, R.K. 2003. Cadmium toxicity induced changes in plant water relations and oxidative metabolism of Brassica juncea L. plants. Journal of Environmental Biology 24: 107-112.

Vega, J.M., Garbayo, I., Dominguez, M.J. and Vigar, J. 2006. Effect of abiotic stress on photosynthesis and respiration in Chlamydomonas reinhardtii: induction of oxidative stress. Enzyme and Microbial Technology 40: 163-167.