Postharvest physiology of cut Gardenia jasminoides flowers

Authors: CELIKEL, FISUN - Ondokuz Mayis University; REID, MICHAEL - University Of California, Davis; Jiang, Cai-Zhong

Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2019
Publication Date: 2/5/2020
Citation: Celikel, F.G., Reid, M.S., Jiang, C. 2020. Postharvest physiology of cut Gardenia jasminoides flowers. Scientia Horticulturae. 261. https://doi.org/10.1016/j.scienta.2019.108983.
DOI: https://doi.org/10.1016/j.scienta.2019.108983

Interpretive Summary: Gardenia jasminoides is the most popular cultivated gardenia species. It is an evergreen flowering shrub plant with bright green leaves and fragrant white flowers. Gardenias are commonly grown in temperate regions as outdoor and indoor plants and prefer an acidic soil, high humidity and night temperatures around 15.5 °C. Higher temperatures and low light intensity cause flower bud abscission. Gardenia flowers are considered very perishable and the cut flowers are primarily used in weddings, harvested as naked buds that are opened manually, and decorated with a rosette of plastic leaves. Gardenia petals turn brown when crushed, and recommended holding buds by the stem to minimize petal bruising. Cut flowers are misted with water, or sprayed with an anti-transpirant to reduce water loss during postharvest handling and transport. Even on the plant, gardenia flowers senesce within four days of opening, and the vase life of cut gardenia flowers is two to four days. Because of this short postharvest life, gardenias have not been considered appropriate for use as cut flowers in arrangements. There consequently has been little study of their postharvest characteristics. The flowers are suggested to be ethylene insensitive and preservative solutions are recommended as a means of extending their life. The optimal harvest stage is suggested to be almost fully open. In a transcriptome analysis of petal senescence of gardenia flowers on potted plants, Tsanakas et al. demonstrated significant changes in expression of transcription factors (TFs) including some from TF families known to be associated with hormone responses, and in particular ethylene responses. In our previous research, we demonstrated that spray treatments with 100 mg L-1 Thidiazuron (TDZ) or a 6-BA + GA4+7 mixture (‘Fascination’) spray treatments provided a modest increase in flower vase life. In the present study, we investigated the postharvest physiology of Gardenia jasminoides, and a range of postharvest treatments that might permit its use as a cut flower. The effects of different vase solution treatments, containing a range of biocides, acidulants, carbohydrate sources and/or growth regulators on the postharvest performance of cut gardenia flowers were studied by measuring water uptake (WU), water loss (WL) and relative fresh weight (RFW) of the flowers during vase life. In deionized water (DI), gardenia flowers wilted after two to three days. Pulse treatment with silver thiosulfate (STS) to inhibit ethylene responses had no effect on vase life. However, abscisic acid (ABA) treatment increased vase life to five days by reducing WL and maintaining RFW. Including a cytokinin, benzyl adenine (BA), in the vase solution was the most effective plant growth regulator treatment, doubling vase life to five and a half days. Vase solutions containing a commercial flower preservative, or combining citric acid, sucrose and aluminum sulfate also doubled the vase life of gardenia flowers. NaOCl in the vase solution provided little benefit, but acidification with aluminum sulfate (AS) or citric acid (CA) increased initial WU and extended vase life. The results suggest that improving water uptake is important for extending the vase life of cut gardenia flowers, and that acidification of the vase solution is an effective tool.

Technical Abstract: We investigated the postharvest physiology of Gardenia jasminoides, and a range of postharvest treatments that might permit its use as a cut flower. The effects of different vase solution treatments, containing a range of biocides, acidulants, carbohydrate sources and/or growth regulators on the postharvest performance of cut gardenia flowers were studied by measuring water uptake (WU), water loss (WL) and relative fresh weight (RFW) of the flowers during vase life. In deionized water (DI), gardenia flowers wilted after two to three days. Pulse treatment with silver thiosulfate (STS) to inhibit ethylene responses had no effect on vase life. However, abscisic acid (ABA) treatment increased vase life to five days by reducing WL and maintaining RFW. Including a cytokinin, benzyl adenine (BA), in the vase solution was the most effective plant growth regulator treatment, doubling vase life to five and a half days. Vase solutions containing a commercial flower preservative, or combining citric acid, sucrose and aluminum sulfate also doubled the vase life of gardenia flowers. NaOCl in the vase solution provided little benefit, but acidification with aluminum sulfate (AS) or citric acid (CA) increased initial WU and extended vase life. The results suggest that improving water uptake is important for extending the vase life of cut gardenia flowers, and that acidification of the vase solution is an effective tool.