Intra-cultivar variability of the soil-to-grain transfer of fallout Cs-137 and Sr-90 for winter wheat

Differences between the root uptake of fallout radionuclides by different cultivars ('inter-cultivar' variability) growing on the same field may be influenced not only by genetic differences of the cultivars, but also by the spatial variability of the soil-to-grain transfer within the cultivation area of each cultivar. This 'intra-cultivar' variability was investigated in 2001 and 2002 for Cs-137 and Sr-90 using three winter wheat cultivars with four replicates for each cultivar at three different sites in Bavaria, Germany. The intracultivar variability proved to be in the same range as the inter-cultivar variability which was determined earlier at the same sites for both radionuclides. An ANOVA of the Cs-137 data set revealed that the variability of the Cs-137 soil-to-grain transfer was caused by the soil and climate (year) at the field sites and the interaction of cultivar and field. A significant contribution of the factor 'cultivar' alone to the variability could not be detected. This may be due to the complex environmental conditions to which plants are exposed in field experiments. To find wheat cultivars with minimal uptake of fallout radionuclides it may be better to examine the molecular mechanisms of their root uptake in order to identify targets for breeding safer plants. (c) 2006 Elsevier Ltd. All rights reserved.