Soil-to-grain transfer of fallout 137Cs for 28 winter wheat cultivars as observed in field experiments

In order to find wheat cultivars with a minimum soil-to-grain transfer of fallout (137)Cs, 28 winter wheat cultivars were investigated at 3 different sites with different soil types in Bavaria, Germany. Each cultivar was grown on an area of 10 m(2) and harvested in August 1999. The soil-to-grain concentration ratios (C(r)) of (137)Cs varied by a factor of up to 3 from cultivar to cultivar at a given site and from site-to-site for a given cultivar. The mean C(r) values at the three sites, 4.2 x 10(-4), 4.9 x 10(-4) and 7.5 x 10(-4), differed significantly. The fact that no cultivar showed similar C(r) values at the three sites indicates a strong influence of the soil on C(r). The cultivars Flair, Kornett and Previa showed a minor uptake of (137)Cs compared with the mean of all cultivars at each site. Unlike (137)Cs, the (40)K concentrations in the wheat grains varied only within a small range (122-190 Bq kg(-1)) at each site, which is due to the potassium regulation by the plants. For both radionuclides, the differences between the root uptake characteristics of the cultivars may not only be explained by an inter-cultivar variability due to genetic differences between the cultivars, but also by an intra-cultivar variability due to different soil conditions.