Influences of fulvic acid on bioavailability and toxicity of selenite for wheat seedling and growth.

The influences of fulvic acid (FA) on bioavailability and toxicity of selenite for wheat seedling and growth were studied by greenhouse hydroponic experiment. The results showed that seed germination, embryo development, 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 selenite exceeded 1.0 mg/L, toxic effects were observed for most of the measured indicators. The presence of FA could reduce the bioavailability of Se and could antagonize the toxic effects of Se. The reasons for the 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.