عنوان مقاله [English]
Background and Objectives
Recently, the use of cut flowers has increased, and some of these cut flowers (Lily, Rose etc.) are among the most used for decorative purposes. With this boom in popularity has also come a rise in the need for commercial use, and very little academic literature exists on how to best utilize the preservative solutions (here 8-HQC and essential oils) to prolong cut flowers vase life keeping their full quality. The vase life of Lily is usually short due to vascular occlusion. The use of synthetic chemical fungicides to protect cut flowers raises environmental and human health concerns because of chemical residue routinely found on food meant for consumption. Thus, biocides showing insignificant toxicity to human and organisms are more desirable and less likely to cause negative environmental effects.
Materials and Methods
The chemical composition of essential oils extracted from the endemic Iranian plants Satureja hortensis L., Thymus vulgaris L. and Citrus limon L. was studied in order to evaluate their efficacy as a substitute for synthetic chemical that was used as preservative-solutions. The effects of essential oils (250 mg L-1) individually and 8-hydroxyquinoline citrate (8-HQC) with sucrose 3% were evaluated. Cut flowers were pulsed for 12 h in different preservative solutions, followed by storage in dry and wet conditions (in distilled water) at 8˚C for 15 days, and then all treated cut flowers were kept in room temperature to evaluate commercial vase life. At the end of commercial vase life, parameters such as relative fresh weight, amount of chlorophyll, phenol, anthocyanin, protein and carbohydrate, vase life and antioxidant enzyme activities were measured. In this experiment, flowering stems were arranged using a completely randomized design.
Limonene was identified as major component of C. limon L. essential oil, whereas Carvacrol was the major component in S. hortensis L. and Th. vulgaris L. Results showed that applying all essential oil treatments or 8-HQC increased positive characteristics and vase life compared with control. However, among all these treatments, the flowers treated with Thyme essential oil plus 3% sucrose or 8-HQC were kept in wet storage condition showed best vase life. Based on our results, new antimicrobial agents such as limonene, thymol and carvacrol in combination with 3% sucrose had a positive effect on the vase-life and relative fresh weight. The senescence of cut flowers is associated with a series of highly regulated physiological and biochemical processes, including breakage of water balance, degradation of photosynthetic pigment, decrease in metabolic constituents, and loss of membrane integrity. In our experiment, Thyme essential and 8-HQC oil treatments were reduced degradation of leaf protein and chlorophyll content which was seen in the controls. Essential oils derived from plants such as T. vulgaris are particularly valuable because of their antibacterial and antioxidant properties.
In conclusion, using various concentrations of essential oils and 8-HQC in preservative solutions showed promising prospects for the utilization of natural essential oils or plant extracts in extending lily vase-life. The proposed mechanism of action, e.g. inhibition of the growth of bacteria in the vase water or inside the xylem vessels of the flower stem needs further elucidation.