Growth and 137Cs uptake of four Brassica species influenced by inoculation with a plant growth-promoting rhizobacterium Bacillus pumilus in three contaminated farmlands in Fukushima prefecture, Japan

The effectiveness of the plant growth-promoting rhizobacterium Bacillus pumilus regarding growth promotion and radiocesium (137Cs) uptake was evaluated in four Brassica species grown on different 137Cs contaminated farmlands at Fukushima prefecture in Japan from June to August 2012. B. pumilus inoculation did not enhance growth in any of the plants, although it resulted in a significant increase of 137Cs concentration and higher 137Cs transfer from the soil to plants. The Brassica species exhibited different 137Cs uptake abilities in the order Komatsuna > turnip > mustard > radish. TF values of 137Cs ranged from 0.018 to 0.069 for all vegetables. Komatsuna possessed the largest root surface area and root volume, and showed a higher 137Cs concentration in plant tissue and higher 137Cs TF values (0.060) than the other vegetables. Higher 137Cs transfer to plants was prominent in soil with a high amount of organic matter and an Al-vermiculite clay mineral type.