PROBLEM TO BE SOLVED: To provide an adjuvant for improving the effect to a plant of 5-ALA by combination use with 5-ALA and an agent containing it, and to provide a method of using the adjuvant. SOLUTION: This adjuvant is of 5-aminolevulinic acid and an agent containing it, and contains one or more selected from amino acid, organic acid, sugars, sugar alcohols, and betaines. Absorption of 5-aminolevulinic acid of a plant is increased by combination use with the agent containing 5-ALA, and the effect can be exhibited by reducing the rate limiting factor of photosynthesis or biosynthesis within a plant body. COPYRIGHT: (C)2012,JPO&INPIT
