The short day or the long dark photoperiods stimulates the formation of the growth inhibiting hormones. Abscissin the growth inhibiting hormone which is present in greater amount in the dormant bud. The leaves perceive the photoperiodic effect and the buds acts as the sites of perception and induces the dormancy in the plant. ABA translocated to the buds which brings about the temporary suspension of the metabolic activities occurs. The meristematic region is protected with a number of leaves called as the bud scales which are thick, wax coated with dense hair. So that it provides the insulation layer to the meristematic zone so as to prevent the cold injury. The dormancy in the buds can be broken by subjecting to the long photoperiodic condition or interrupting the long dark period. The bud dormancy can also be broken by applying the cytokinins, gibberellins, cytokinins, ethylene, chlorohydrins and thiourea etc.
