Effects of elevated carbon dioxide on metal transport in soil-crop system: results from a field rice and wheat experiment

摘要

Purpose Climate changes have significant impacts on crop yield, and also on crop quality related to food safety and human health. This study investigated the influences of atmospheric carbon dioxide (CO2) enrichment on cereal metal accumulation in soil-crop system. Materials and methods Field rotation experiments of rice (Oryza sativa) and winter wheat (Triticum aestivum) were conducted by simulating elevated CO2 concentrations (e[CO2]) in 12 open-top chambers (OTCs). The treatments included the ambient [CO2] (CK), 80 ppm (T1) and 200 ppm (T2) above ambient condition, respectively. Different parts of above-ground plant samples were analyzed for metal concentrations (Cu, Zn, Fe, Mn; Ca, Mg) at the key growth stages, assisted with analyses of soil pH, metal bioavailability, and transfer factors (TFs). Results and discussion The result patterns were opposite for rice and wheat. After the increased transport from rhizospheric soil solution due to the metal mobilization by declined pH, most metals increased their distributions in rice grain, husk, and stem than leaf. While for winter wheat, though soil metal bioavailability was also increased, their distributions in grain, husk, and stem were decreased owing to possible carbohydrate dilution effect or cation competition, except some macro metals distributed more in leaf. Conclusions Since results of metals and crops are not always consistent among various reports, the mechanisms of essential/toxic metal transport in soil-crop system affected by climate change and its impacts on human health deserve further studies.