Abstract:

The combined effects of elevated CO₂ and cadmium (Cd) on photosynthetic rate, chlorophyll fluorescence and Cd accumulation in hyperaccumulator Sedum alfredii Hance were investigated to predict plant growth under Cd stress with rising atmospheric CO₂ concentration. Both pot and hydroponic experiments were conducted and the plants were grown under ambient (350 µL L⁻¹) or elevated (800 µL L⁻¹) CO₂. Elevated CO₂ significantly (P < 0.05) increased Pn (105%–149%), Pn_max (38.8%–63.0%) and AQY (20.0%–34.8%) of S. alfredii in all the Cd treatments, but reduced chlorophyll concentration, dark respiration and photorespiration. After 10 days growth in medium with 50 µM Cd under elevated CO₂, PSII activities were significantly enhanced (P < 0.05) with Pm, Fv/Fm, Φ(II) and qP increased by 66.1%, 7.5%, 19.5% and 16.4%, respectively, as compared with ambient-grown plants. Total Cd uptake in shoot of S. alfredii grown under elevated CO₂ was increased by 44.1%–48.5%, which was positively correlated with the increase in Pn. These results indicate that elevated CO₂ promoted the growth of S. alfredii due to increased photosynthetic carbon uptake rate and photosynthetic light-use efficiency, and showed great potential to improve the phytoextraction of Cd by S. alfredii.

Li TQ, Tao Q, Di ZZ, Lu F, Yang XE (2015) Effect of elevated CO₂ concentration on photosynthetic characteristics of hyperaccumulator Sedum alfredii under cadmium stress. J Integr Plant Biol 57: 653–660. doi: 10.1111/jipb.12307

Key words: Cadmium, chlorophyll fluorescence, elevated CO₂, photosynthesis, Sedum alfredii