Growth Responses of Holcus lanatus L. (Velvet Grass) in Soils Contaminated with Cesium or Strontium

Radiocesium (r-Cs) and radiostrontium (r-Sr) released from nuclear accidents (e.g., Chornobyl, Fukushima) and routine operations (reactors, reprocessing) pose environmental and health concerns. Their primary pathway to humans is through plant uptake and subsequent bioaccumulation within the food chain. While soil amendments with potassium (K) and calcium (Ca) are known to mitigate r-Cs and r-Sr uptake, respectively, the impact on plant growth remains unclear. This study investigates the effects of Cs and Sr on the growth of Holcus lanatus L. seedlings under hydroponic and soil conditions with varying Cs and Sr concentrations. Stable isotopes of Cs and Sr served as non-radioactive analogs. Seedling growth was assessed across a range of Cs and Sr concentrations (≤1 and ≥4 mg L⁻¹). The impact of the addition of K and Ca on Cs/Sr uptake in amended soils was also evaluated. Additionally, this study examined how Cs and Sr amendments affected the influx rates of other nutrients in H. lanatus. Higher Cs and Sr concentrations (≥4 mg L⁻¹) significantly inhibited seedling growth, while lower concentrations had no effect. Notably, H. lanatus exhibited moderate Cs tolerance and strong Sr tolerance. Furthermore, K and Ca supplementation in Cs/Sr-amended soils demonstrably reduced plant uptake of these elements. This study also observed alterations in the uptake rates of other nutrients within H. lanatus due to Cs/Sr addition. This study suggests that H. lanatus exhibits moderate tolerance to Cs and Sr contamination, potentially making it suitable for revegetation efforts in contaminated grasslands. Additionally, K and Ca amendments show promise as a strategy to mitigate plant uptake of these radioisotopes further. These findings contribute to the development of safer revitalization strategies for areas impacted by nuclear accidents.