Effects of high CO2 and low O2 on biochemical changes in cut Dendrobium orchids

Low-Oxygen Responses of Cut Carnation Flowers Associated with Modified Atmosphere Packaging

Gaseous factors affect post-harvest physiological processes in horticultural crops, including ornamental flowers. However, the molecular responses of cut flowers to the low-oxygen conditions associated with modified atmosphere packaging (MAP) have not yet been elucidated. Here, we show that storage of cut carnation flowers in a sealed polypropylene bag decreased the oxygen concentration in the bag to 3-5% and slowed flower opening. The vase life of carnation flowers after storage for seven days under MAP conditions was comparable to that without storage and was improved by the application of a commercial-quality preservative. The adenylate energy charge (AEC) was maintained at high levels in petals from florets stored under MAP conditions. This was accompanied by the upregulation of four hypoxia-related genes, among which the HYPOXIA-RESPONSIVE ETHYLENE RESPONSE FACTOR and PHYTOGLOBIN genes (DcERF19 and DcPGB1) were newly identified. These results suggest that hypoxia-responsive genes contribute to the maintenance of the energy status in carnation flowers stored under MAP conditions, making this gas-controlling technique potentially effective for maintaining cut flower quality without cooling.

Effects of active and passive modified atmosphere packaging on biochemical properties of cut Dendrobium orchid flowers

Optimal storage conditions are essential to preserving the quality of postharvest produce and cut flowers during transportation, especially to overseas destinations. As a result, this research investigated the effects of active and passive modified atmosphere packaging (MAP) on the biochemical properties of cut Dendrobium Sonia orchid flowers. In active MAP, the orchid flowers were wrapped in MAP plastic film filled with 5 % carbon dioxide (CO₂) and 2 % oxygen (O₂). Meanwhile, in passive MAP the flowers were stored inside MAP plastic film without filling with 5 % CO₂ and 2 % O₂. The experimental MAP plastic films were polyethylene, low density polyethylene, high density polyethylene, polypropylene, and polyvinyl chloride films. The biochemical parameters included storage life, respiration rate, ethylene production, internal O₂ and CO₂, anthocyanin content, protein degradation, and electrolyte leakage. The results showed that the average storage life of orchid flowers under passive MAP condition was 9–15 days, depending on the plastic film types. The longest storage life of 15.66 days was achieved with polypropylene film. The storage life of orchid flowers in active MAP was 9.33 days on average. Without MAP (control), the storage life was 7 days under normal atmosphere condition (0.03 % CO₂ and 21 % O₂). The experiments also demonstrated that MAP efficiently reduced respiration rate, ethylene production, anthocyanin degradation, protein degradation, and electrolyte leakage. Unlike existing research on MAP which focused primarily on extending the shelf life of fresh produce or cut flowers, this study comparatively investigated the biochemical properties of cut orchid flowers stored in MAP environment, in addition to the storage life.