ABSTRACT. Stress conditions are known to promote reproductive sprouting and flowering in Citrus. However, signalling involved in stress perception and flowering induction remains obscure. To gain insight into the mechanism involved in stress signalling, the aim of this work was to study the physiological and biochemical changes triggered by water stress and their relationship with budbreak in ?Valencia? orange (C. sinensis (L.) Osb.) and ?Ellendale? tangor (C. reticulata Bl.). Water stress was promoted by subjecting plants to 70-days of water deficit (water potential:Ψw