The present invention relates to the field of environmental protection, and in particular to a leaf surface barrier for ac- curately controlling cadmium absorption and transport related gene expression in rice, and an application thereof. The present inven- tion comprises: reducing a raw material, i.e., selenious acid or selenite, by using ascorbic acid to generate a nanogel, and then emul- sifying the managed for peptization to obtain a leaf surface barrier for accurately controlling cadmium absorption and transport re- lated gene expression in rice and then mixing the leaf surface barrier with a silica sol to obtain a composite selenium and silica sol leaf surface barrier. The present invention also provides a leaf surface barricading method for accurately controlling cadmium ab- sorption and transport related gene expression in rice. By applying the leaf surface barrier, the silica sol or the composite selenium and silica sol leaf surface barrier having a particular atomization degree and a particular contration by means of foliar spray dur- ing a particular growth period of rice and within a particular time, the cadmium accumulation in rice can be effectively reduced. Ap- plying the present invention to a moderately or lightly polluted field can enable cadmium content in rice to satisfy the food hygiene standards, and therefore is significant for achieving the safe use of the large area of field polluted by heavy metal cadmium in China.
