Compounds represented by the following general formula (I) or salts thereof: wherein R1 represents hydrogen atom, hydroxyl group, or an alkoxy group; R2 represents hydroxyl group or an alkoxy group which may be substituted; R3 represents hydrogen atom or an alkyl group which may be substituted; Y represents —CH═CH— or —CH2—; n represents 0 or 1; Ar represents an aryl group which may be substituted or a heteroaryl group which may be substituted, which are useful as inhibitors against the abscisic acid biosynthesis and plant growth regulators.