Effects of 6-Benzylaminopurine–Calcium Chloride–Salicylic Acid on Yellowing and Reactive Oxygen Metabolism of Broccoli

In this study, we investigated the effects of 6-benzylaminopurine (6-BA)–calcium chloride (CaCl2)–salicylic acid (SA) treatment on the yellowing and reactive oxygen metabolism of harvested broccoli heads. We dipped fresh broccoli heads in a compound solution (0.6 mmol/L 6-BA + 40 mmol/L CaCl2 + 3 mmol/L SA) for 5 min and then stored them at 23 °C for 4 days. The results showed that the 6-BA–CaCl2–SA postharvest treatment effectively retarded the increase in color values (e.g., variations from black to white, from green to red, and from blue to yellow) and the decline in chlorophyll content of the broccoli heads. Compared with the control broccoli, the rate of superoxide anion radical (O2·−) production and the hydrogen peroxide (H2O2) content were lowered by the treatment. We also found significant differences in the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in the treated broccoli. Based on these results, we consider 6-BA–CaCl2–SA to inhibit the accumulation of reactive oxygen, delay the degradation of chlorophyll, and prolong the shelf life of broccoli heads at 23 °C.