EFFECT OF EXOGENOUS PUTRESCINE IN DELAYING SENESCENCE OF BROCCOLI (BRASSICA OLEARACEA VAR. ITALICA) FLORETS

The rapid senescence is the main limiting factor of postharvest life in broccoli florets. In this study, effects of different concentrations of putrescine (Put) on delaying florets senescence of two broccoli cultivars, ‘General’ and ‘Liberty’ during cold storage were investigated. Broccoli florets were treated with 0.5, 1 and 1.5 mM Put and distilled water was used as control. The treated florets was placed in polyethylene bag and transferred to storage with 0±1°C and 90±5% RH. Characteristics such as general visual quality, total chlorophyll, lipid peroxidation, activity of lipoxygenase (LOX), superoxide dismutase (SOD) and peroxidase (POD) was determined at harvest time, after 40 days cold storage and 2 additional days in room temperature. The results showed that 1.5 mM Put delayed chlorophyll degradation and senescence and improved florets quality in both ‘General’ and ‘Liberty’ cultivars. Application of Put delayed more lipid peroxidation during long term storage. Also, it suppressed increasing POD and LOX activity and maintained higher SOD activity, and delayed florets senescence in broccoli during long term storage.