The present invention relates to the use of a polypeptide with the biological activity of a sucrose-6-phosphate phosphatase which, if not present, brings about growth retardation symptoms and chlorotic leaves and which is encoded by the nucleic acid sequences SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5 or by a functional equivalent of SEQ ID NO:1, SEQ ID NO:3 or SEQ ID NO:5 as target for herbicides. Moreover, the present invention relates to the use of the abovementioned polypeptides in a method for identifying herbicidal or growth-regulatory compounds which inhibit sucrose-6-phosphate phosphatase. Moreover, the invention relates to the use of these compounds which have been identified via the method as herbicides or growth regulators.