The effect of time and stage of preharvest spraying by spermine and γ-aminobutyric ‎acid on vase life and postharvest quality of "Stanza" cultivar of Gerbera cut flowers

In order to maintain the postharvest quality and vase life of the "Stanza" cultivar of gerbera cut flowers, an experiment was designed as split-plot for time based on a completely randomized design, with four replications, at 2018 in horticulture department of Ilam university. The treatments consisted of preharvest application of Spermine 2 mM and γ-Aminobutyric acid 2mM (GABA), as sub-plot, at two stages (2T) of spraying (the stage of emergence of flower branch and 10 days later) and three stages (3T) of spraying (the stage of emergence of flower branch, 7 and 10 days later) that investigated, as the main plot, at 0, 3, 6 and 9 days postharvest at 22±1 °C and relative humidity of 65 to 70%. The results showed that, respectively, spermine 3T, spermine 2T, GABA 3T and GABA 2T treatments increased vase life and maintaind postharvest quality of Gerbera cut flowers compared to the control. The results of the 9th day showed that the highest fresh weight, absorption of vase solution (VSU), soluble solids, protein, phenol and total flavonoid, activity of the catalase (CAT), guaiacol peroxidase (GPX), superoxide dismutase (SOD) and Phenylalanine ammonia lyase (PAL), as well as the lowest ion leakage (EL), malondialdehyde MDA and polyphenol oxidase (PPO) activity respectively were observed in Spermine and GABA treatments, and in some of the studied traits, there was no significant difference between two and three stages of spraying. Therefore, the use of spermine 3T as the best treatment in present study is recommended as an application method to increase the vase life of "Stanza" cultivar of gerbera cut flowers.