Effects of Substrate Water Contents on Post-Shipping Performance of Phalaenopsis

Phalaenopsis is one of the most popular orchids worldwide. To export the plants with growing medium, they are shipped long distances in total darkness from the producing countries to the destination market countries. In this study, the effects of substrate (sphagnum moss) water contents before simulated dark shipping (SDS) on post-shipping performance were investigated in Phalaenopsis. In experiment 1, the P. 'V3' and P. 'Lovely Angel' plants were dehydrated for 0 (control), 1, 2, 3, or 4 weeks, and they were kept in the dark for 20 days at 17 degrees C for SDS. In experiment 2, P. 'V3' plants dehydrated from 0 to 4 weeks were packed in a box and then placed in a refrigerated container for 30 days at 18 degrees C. With a prolonged dehydration from 0 to 4 weeks, substrate volumetric water contents (VWC) were decreased both before and after SDS. In experiment 1, the relative leaf chlorophyll content (SPAD) was gradually decreased during SDS and recovered after the end of SDS in the plants dehydrated for 0 and 1 week. The Fv/Fm value was maintained from 0.7 to 0.8 regardless of dark shipping and substrate VWC. Dehydration promoted days to inflorescence emergence and flowering compared to control plants. In experiment 2, SPAD value was increased in the plants dehydrated from 1 to 4 weeks rather than control plants, and the plants had darker green leaves. Leaf abscission was increased with increased yellowed leaves at 25 days after SDS. The number of abscised leaves was decreased with prolonged dehydration and had the greatest reduction in the plants dehydrated for 3 weeks by 31% VWC before SDS. Days to inflorescence emergence and flowering were shortened in the plants dehydrated for 3 and 4 weeks, and the plants dehydrated for 3 weeks had the most flowers. Therefore, we recommend substrate relative water content of 30% VWC before shipping to reduce the detrimental effects caused by long-term dark shipping in Phalaenopsis with moss substrate.