The present invention relates to sulfonamide derivatives of formula (I) where the substituents R1-R6 and R8, L, A and n are as defined in the application, to plant growth regulator compositions comprising them and to methods of using them for controlling the growth of plants, improving plant tolerance to abiotic stress (including environmental and chemical stresses), inhibiting seed germination and/or safening a plant against phytotoxic effects of chemicals.