INFLUENCES OF FULVIC-ACID ON BIOAVAILABILITY AND TOXICITY

The influences of fulvic acid (FA) on bioavailability and toxicity of selenite for wheat seedling and growth were studied by greenhouse hydr oponic experiment. The results showed that seed germination, embryo de velopment, and growth were stimulated by selenite in the concentration range of 0.1-1.0 mg/L. In the presence of FA, the stimulation effects were more obviously observed. However, when the concentration of sele nite exceeded 1.0 mg/L, toxic effects were observed for most of the me asured indicators. The presence of FA could reduce the bioavailability of Se and could antagonize the toxic effects of Se. The reasons for t he antagonism were caused by the inhibitory effects of FA on uptake of Se by plants and by the stimulating effects of FA on plant growth.