PURPOSE:A plant growth regulator useful for promoting growth of callus, etc., and increasing yield of vegetables such as tomato, lettuce, etc., in water culture, etc., showing improved plant growth promoting or suppressing action, containing a specific ammonium salt as an active ingredient. CONSTITUTION:A plant growth regulator contains an ammonium salt such as N-lauryl-trimethylammonium bromide, etc., shown by the formula [R is 8-16C alkyl, alkenyl or alkynyl; A, B and C are (substituted) lower alkyl, (substituted) lower alkenyl, (substituted) aralkyl, (substitute) aryl, saccharide residue of A and B or A, B and C are bonded to form ring which may contain hetero atom or substituent group in the ring; X is acid residue] as an active ingredient and shows plant growth promoting effects in a low concentration side and plant growth suppressing effects in a high concentration side. EFFECT:Has germination promoting effects on seeds, seedling, etc., properly suppressing effects on growth of fruit trees, herbicidal or weeding effects, etc.
