Influence of iron plaque on chromium accumulation and translocation in three rice (Oryza sativa L.) cultivars grown in solution culture

Abstract

Hydroponic experiments were conducted to investigate the role of iron plaque on root surface in chromium accumulation and translocation in three rice cultivars (90-68-2, CDR22 and Jin 23A). Rice seedlings were grown under 1.0 mg L⁻¹ trivalent chromium (Cr(III)) stress with and without phosphorus (P) treatments. P addition significantly increased the shoot and root biomass in all three rice cultivars. In the absence of P, the amounts of iron plaque (DCB-extractable Fe) on the root surface increased resulting in the increase of Cr accumulation in iron plaque. Compared to that with P treatment, Cr concentrations in iron plaque without P treatment were enhanced by 2–3 folds in the three rice cultivars. There was a significantly positive correlation between DCB-extractable Cr and DCB-extractable Fe on the root surface of the three rice cultivars. There were no significant effects on Cr concentration in roots and shoots between P treatments, but significant differences among cultivars were observed. Cultivar Jin 23A had the lowest Cr concentration both in roots and shoots regardless of P treatment. The results suggest that iron plaque could be a trap for immobilising Cr from environment but may not affect Cr uptake and translocation. Screening and breeding the cultivars with low Cr accumulation is considered as the most effective approach in Cr contaminated areas.

Keywords:

• chromium
• iron plaque
• rice
• phosphorus

Acknowledgements

We would like to thank Professor Li Damo at Institute of Subtropical Regional Agriculture, Chinese Academy of Sciences for supplying rice seeds. The project was supported by National Natural Science Foundation of China (21377152), national heavy metal pollution control special ‘soil heavy metals pollution control in the Dahuan River Watershed in Huan Jiang County, Guangxi Zhuang Autonomous Region of China’, and by National Major Programs of Water Pollution Control (No. 2009ZX07212-001-05), and by the Open Fund Project of Provincial Key Laboratory of Jiangxi Province Academy of Sciences (2012-KLB-1).