The invention discloses a preparation method of microalgae nano-
selenium and application of biotransformed nano-
selenium in prevention and treatment of
plant late
blight. The novel preparation method of the microalgae nano-
selenium comprises the following steps: firstly, extracting an
intracellular extract of
chlorella pyrenoidosa, and then adding
sodium selenite into the
intracellular extract to carry out nano-selenium conversion; compared with an existing reported method that after
sodium selenite is added into a microalgae
living body culture solution to be converted into nano-selenium,
algae is taken to break cells, and the nano-selenium is collected, the method has the advantages that the microalgae
living body does not need to be used when the nano-selenium is biologically converted, and the subsequent complicated nano-selenium separation and purification steps can be avoided; the nano-selenium obtained by converting the
intracellular extract can be directly applied. Experiments prove that the effect of the nano-selenium obtained through
biotransformation on inhibiting
phytophthora infestans of potato late
blight pathogenic bacteria is obviously better than that of chemically synthesized nano-selenium, and the nano-selenium obtained through
biotransformation has an obvious effect on preventing and treating potato late
blight and has an obvious effect on promoting
plant growth.