THE DETECTION OF THE ACCUMULATION OF SILICON IN PHALAENOPSIS (ORCHIDACEAE)

Small particles along the veins of leaves in Phalaenopsis contain sili con. The silica bodies are spherical in shape and 5-30 mu m in diamete r. In the in vitro cultured plantlets, they grow differently in size, depending on the developmental stage of the plantlets and the concentr ation of silicon added to the medium. The growth of the silica body wa s increased by increasing the concentration of CaSiO3 from 0.01 to 0.5 mg l-1 and was maximized from 0.5 to 1.0 mg l(-1). In the medium with 1.0 mg l(-1) CaSiO3, they grew to a size larger than that of the gree nhouse plants after 6 months in culture. The sensitivity of the growth of the silica bodies to the environmental concentration of silicon wa s then suggested to be a useful indicator for studying the uptake of s ilicon in plants. (C) 1995 Annals of Botany Company