Radiocaesium accumulation in rice cultivars in a low-potassium paddy field in Fukushima

The accumulation of radiocaesium in the grains of 15 rice cultivars was monitored in 2014 and 2015. The study area was a local paddy field with low soil potassium concentrations, where highly radiocaesium contaminated rice had been commercially harvested because of the Fukushima Daiichi Nuclear Power Plant accident. The concentrations of radiocaesium in the resulting brown rice were all high, ranging from 150 to 960 Bq kg(-1) (decay-corrected to December 2011), and the transfer factors were approximately 10- to 25-fold higher than those of previous studies. In this study, the trend of radiocaesium accumulation in each of the improved indica, aus, and japonica cultivars became clear, whereas none of the previous studies showed a clear trend in each cultivar group. The high radiocaesium accumulation in improved indica cultivars (e.g. Takanari) should be taken into account when considering the expansion of rice cultivation for processing and forage.