Time-course analysis of radiocesium uptake and translocation in rice by radioisotope imaging

Abstract

The pattern of real-time 137Cs uptake by plants was visualized using a macroscopic real-time radioisotope imaging system. We found that 137Cs was easily taken up by rice plants only when it was dissolved in a liquid medium. In contrast, only a small amount of 137Cs was taken up when the same liquid medium containing 137Cs was added to the soil and supplied to the rice plants. This result demonstrates the intensive Cs adsorptive property of the soil. When rice was grown hydroponically in K-sufficient environment followed by K withdrawal for 2 days, 137Cs was taken up easily compared with the rice without K deficiency. The application of K was shown to be an effective method for preventing radiocesium uptake by rice plants. However, K-deficiency was found to have little effect on the xylem loading process of Cs. Understanding the Cs translocation processes and evaluating the factors affecting each process based on experimental evidence could facilitate the development of an agricultural technique to reduce the radiocesium content in the edible parts of plants.