The invention relates to substituted 6-anilino-9-heterocyclylpurine derivatives of formula I wherein R denotes one to five substituents independently selected from the group hydrogen, halogen, hydroxy, amino, alkyloxy and alkyl group, R2 is selected from the group comprising amino, halogen, hydroxy, thio, and alkylthio group, Cyc is five- or six-membered heterocyclic ring containing one oxygen atom. The derivatives are useful for inhibition of plant stress.