Abstract
Growth and resource allocation of three black sand plants namely Cakile maritima, Senecio glaucus and Rumex pictus were investigated in a greenhouse experiment. The effect of absorbed radionuclides on the plant growth was monitored at different growth stages including seedling, juvenile, flowering, fruiting and senescing stages. The study reveals that growth attributes including relative growth rate, net assimilation rate, leaf are index and specific leaf area, dry matter allocated to stem and leaves and number of reproductive organs decreased with the increase of radionuclide content of the plant, while the dry matter allocated to root and reproductive organs and root to shoot weight ratio were associated with high level of radionuclides. Because of their tolerance to high levels and accumulation of radionuclides, the species C. maritima, S. glaucus and R. pictus could be potential candidate plants for radio-phytoremediation of soils contaminated with uranium and thorium.Key words: Uranium, thorium, plant growth, resource allocation.