AbstractSeedlings ofTriticum aestivumL. were sprayed with menadiol disulfate in water solution. Eight days after spraying, the content of phylloquinone in the shoots was more than twice as high as in shoots of untreated control plants. The application of menadiol disulfate caused a stimulation of the synthesis of phylloquinone. It is possible that menadiol is an intermediate in the biosynthesis of phylloquinone.