Abstract: Studies on the effects of plant growth regulators on potato tubers during storage are important both for storing potatoes safely and for understanding the mechanisms of potato dormancy. In this research, the mid-to-longterm dormancy potato cultivar “Chuanyu 117” and the short-term dormancy cultivar “Favorita” were used as the experimental materials. Potato tubers were treated with three plant growth regulators: gibberellin A₃ (GA₃), chlorpropham (CIPC), or abscisic acid (ABA) for 30 min. Then, tuber germination and the oxidase activity in tuber flesh and bud bases were evaluated during storage. The results showed that GA₃ shortened the germination time of “Chuanyu 117” and “Favorita” by 10.42% and 26.92%, respectively, compared with that in the control (CK). In contrast, ABA and CIPC prolonged the germination time of “Chuanyu 117” by 10.42% and 106.25% respectively, compared with that in the CK. The germination time of “Favorita” treated with ABA was prolonged by 23.08% compared with that in the CK, and the tubers treated with CIPC did not sprout. Moreover, ABA significantly reduced the dormancy amplitude and led to neat tuber sprouting. The polyphenol oxidase (PPO) and peroxidase (POD) activities in tuber flesh and bud bases from cultivars with different degrees of dormancy increased and then decreased during the storage period. The peak activities of PPO and POD occurred during the bud-burst stage of germination, indicating that increased activity of PPO and POD represented physiological processes involved in the breaking of tuber dormancy and sprouting. The three plant growth regulators significantly affected the PPO and POD activities in bud bases and tuber flesh. The activities of PPO and POD in the bud bases were enhanced by GA₃. The activities of oxidases in different parts of non-sprouting tubers were reduced by ABA and CIPC. Application of ABA led to increases in PPO and POD activities during dormancy release, especially in “Chuanyu 117”. These findings reveal some of the physiological mechanisms involved in the breaking of dormancy and acceleration of germination by GA₃, and in the prolonging of dormancy by ABA and CIPC.