Abstract
This study investigated the physiological changes in Phalaenopsis orchids during simulated dark shipping (SDS). Twelve-month-old Phalanopsis Sogo Yukidian ‘V3’ clones were packed and placed at 19°C in darkness for 15, 25, 35, and 45 days. Control plants did not receive SDS. Under extended durations of SDS, the plants exhibited a significant decrease in chlorophyll content, leading to increased leaf yellowing. In addition, longer SDS negatively impacted the percentage of inflorescence emergence and flower quality, with a notable reduction in flower count and size, especially for plants subjected to 35 and 45 days of SDS. Analysis of carbohydrate and hormone status revealed significant changes during SDS. The sucrose content in shoots remained stable initially but decreased sharply after 25 days of SDS. There was a slight decrease in glucose, fructose, and total soluble sugar content in shoots with prolonged SDS, whereas in roots, most sugar contents, except starch, decreased over time. The abscisic acid (ABA) content remained low for the first 25 days but rapidly increased afterward in both shoots and roots. Conversely, cytokinin content, represented by zeatin, decreased during the first 25 days and stabilized thereafter. Indole-acetic acid (IAA) content remained relatively constant, while in roots, salicylic acid (SA) continuously increased with longer dark durations, and jasmonic acid (JA) content diminished. These results indicate that long-term dark shipping in Phalaenopsis orchids induces a significant loss of plant quality, which is closely related to the decrease in carbohydrate resources and hormonal changes.