Growth and 137Cs uptake and accumulation among 56 Japanese cultivars of Brassica rapa, Brassica juncea and Brassica napus grown in a contaminated field in Fukushima: Effect of inoculation with a Bacillus pumilus strain

Abstract Fifty six local Japanese cultivarsof Brassicarapa (40 cultivars), Brassicajuncea (10 cultivars) and Brassicanapus (6 cultivars) were assessed for variability in growth and 137 Cs uptake and accumulation in association with a Bacillus pumilusstrain. Field trial was conducted at a contaminated farmland in Nihonmatsu city, in Fukushima prefecture. Inoculationresulted in different responses of the cultivarsin terms of growth and radiocesium uptake and accumulation. B . pumilus induced a significant increase in shoot dry weight in 12 cultivarsthat reached up to 40% in one B . rapa and three B . juncea cultivars. Differences in radiocesium uptake were observed between the cultivarsof each Brassicaspecies. Generally, inoculationresulted in a significant increase in 137 Cs uptake in 22 cultivars, while in seven cultivarsit was significantly decreased. Regardless of plant cultivarand bacterial inoculation, the transfer of 137 Cs to the plant shoots (TF) varied by a factor of up to 5 and it ranged from to 0.011 to 0.054. Five inoculated cultivars, showed enhanced shoot dry weights and decreased 137 Cs accumulations, among which two B . rapa cultivarsnamed Bitamina and Nozawanahad a significantly decreased 137 Cs accumulation in their shoots. Such cultivarscould be utilized to minimize the entry of radiocesium into the food chain; however, verifying the consistency of their radiocesium accumulation in other soils is strongly required. Moreover, the variations in growth and radiocesium accumulation, as influenced by Bacillus inoculation, could help selecting well grown inoculated Brassica cultivarswith low radiocesium accumulation in their shoots.