Physiological and biochemical changes in ‘Fuyu’ persimmon buds during dormancy

ABSTRACT: This study identified physiological and biochemical changes in ‘Fuyu’ persimmon buds during dormancy. Branches were collected between March and August 2015. Dormancy was evaluated by biological testing of isolated node cuttings at 25 °C and a photoperiod of 16 h. The variables analyzed were water content; reducing sugar content; respiratory activity; activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POD) and polyphenol oxidase (PPO) enzymes; hydrogen peroxide content (H2O2) and lipid peroxidation. At the end of March 2015, the plants were already dormant, and the leaves and fruits present indicated a paradormancy effect. Induction of endodormancy may have occurred in June 2015, when chilling hours (CH) below 7.2 °C and higher CH below 12 °C began to accumulate, which coincided with the period in which there was a decrease in water content and respiratory activity, an increase in reducing sugars, a decrease in SOD, CAT, APX and PPO and an increase in H2O2. After an accumulation of 553 CH below 12 °C, the budburst capacity increased, and the buds presented increased water content, decreased reducing sugars content, increased respiratory activity, low activity in SOD, CAT, APX and POD and high levels of H2O2.