LAUSR

A pot experiment was conducted to study the effects of soil types and osmotic levels on growth and 137Cs accumulation in two blackgram varieties differing in salinity tolerance grown in Fukushima contaminated soils. The contamination levels of the sandy clay loam and clay soil were 1084 and 2046 Bq kg-1 DW, respectively. The 137Cs activity was higher in both plants grown on the sandy clay loam than on the clay soil regardless of soil 137Cs activity concentration. No significant differences were observed in all measured growth parameters between the two varieties under optimal water conditions for both types of soil. However, the growth, leaf water contents and 137Cs activity concentrations in both plants were lower in both soil types when there was water stress induced by addition of polyethylene glycol. Water stress-induced reduction in total leaf area and total biomass, in addition to leaf relative water content, were higher in salt sensitive 'Mut Pe Khaing To' than in salt tolerant 'U-Taung-2' plants for both soil types. Varietal difference in decreased 137Cs uptake under water stress was statically significant in the sandy clay loam soil, however, it was not in the clay soil. The transfer of 137Cs from soil to plants (i.e., root, stem and leaf) was higher for the sandy clay loam for both plants when compared with those of the clay soil. The decreased activity of 137Cs in the above ground samples (leaf and stem) in both plants in response to osmotic stress suggested that plant available 137Cs decreased when soil water is limited by osmotic stress.