Investigation of Physiological and Enzymatic Events During Senescence of Polianthes tuberosa L. Flower under Salicylic Acid and Sodium Nitroprusside Treatments

Recent studies showed that salicylic acid (SA) and nitric oxide (NO) functions as an essential endogenous plant signal molecule. In this study, the regulatory role of NO and SA during the flower senescence of Polianthes tuberosa L. was surveyed. Exogenous application of the NO donor sodium nitroprusside (SNP) and SA could delay flower senescence processes. The flowers were cut and kept in a vase solution of 150 mg/L salicylic acid or 10 mM SNP to examine SA effects on flower development and senescence, increase/decrease of carotenoids, solute carbohydrates, proteins amounts, peroxidation of lipids and activity of an antioxidant enzyme. All of these attributes were positively affected by SA and SNP treatments. The vase solutions containing SA showed a significant decrease in solute carbohydrates (21%) and significant increase in CAT (9%) and APX (39%) activity. Generally, lipids peroxidation activity in flowers increased during the flower senescence with the lowest activity at petal SA treatments. However, SNP retarded the decrease of lipids peroxidation activity during senescence both in flowers compared to the water control. Postharvest SA and SNP application prolonged vase-life in cut Polianthes flowers by improving the reactive oxygen species (ROS) scavenging capacity related to CAT and ASX activity and by better regulation of solute carbohydrates and total proteins disintegration.