Characteristics of ¹³⁷Cs accumulation by Quercus serrata seedlings infected with ectomycorrhizal fungi

ABSTRACT

To study the effects of inoculation with ectomycorrhizal fungi on the accumulation and distribution of radiocesium (¹³⁷Cs) in different plant organs (leaves, stems and roots), we measured the uptake and internal distribution of ¹³⁷Cs by ectomycorrhizal and non-ectomycorrhizal Quercus serrata seedlings in contaminated forest soil. Contamination was a result of the Fukushima Dai-ichi nuclear Power Plant accident. We also estimated the transfer factor (TF), photosynthetic rate and growth of Q. serrata seedlings during the study period, which lasted a full year. The seedlings were grown in plastic pots under field conditions. The soils used in this study had been contaminated with 7200 Bq kg⁻¹ dm of ¹³⁷Cs at Fukushima in 2011. The concentration of ¹³⁷Cs in the plant organs varied between 148, 252 and 294 Bq kg⁻¹ dm in the non-ectomycorrhizal treatment regime for stems, leaves and roots, respectively, and was 47, 69 and 219 Bq kg⁻¹ dm in the ectomycorrhizal treatment regime. The TF was significantly lower (P < 0.01) in the ectomycorrhizal treatment regime EC, and apparent quantum yield (α) and maximum photosynthetic rate at light saturation (P_max) was significantly higher (P < 0.01), although the growth parameters (stem diameter, height and dry mass) did not differ significantly.

KEYWORDS:

• Radiocesium
• forest restoration
• ectomycorrhizal fungi
• bioaccumulation

Acknowledgement

We thank M.S. M. Sasaki and M.S. K. Fujiwara of the Forest Ecology lab of Tokyo University of Agriculture and Technology for assistance with the fieldwork and analysis.

Author Contribution Statement

D.S. Choi, H. Toda and R.D. Guy directed the experiment and managed the experimental facilities. D.S. Choi analyzed ¹³⁷Cs and the various nutrients, and measured the photosynthetic rates. D.S. Choi, H. Toda and R.D. Guy discussed the results and co-wrote the present paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research under Grant B 15H04511 to H. Toda; Grant B 16H02996 to M. Yoshida; and the Ministry of Education, Culture, Sports, Science and Technology (MEXT) under the promotion of international joint research and international industry-university cooperation activities intended for the acceleration of innovation programs.