A closer look at ice cube irrigation in potted phalaenopsis
Method
The effect of ice cube irrigation on the display life and quality of four cultivars of potted Phalaenopsis orchids was, therefore, evaluated. Irrigation treatments included weekly application of three ice cubes or the equivalent volume of room-temperature tap water. The longevity of individual flowers and the overall display life of the orchid plants were determined. Monthly measurements determined the volume of leachate in the outer decorative pots after irrigation. The quantum yield of photosystem II (ΦPSII) in roots and leaves was evaluated monthly to determine if photosynthetic efficiency was affected by the ice irrigation. The temperature in the orchid bark growing media during irrigation events was recorded, and a programmable antifreeze bath was used to determine the temperature at which damage to PSII was observed in orchid roots.
Results
The flower longevity and display life were unaffected by irrigation treatment. In general, the leachate volume over time was the same or lower in ice irrigated orchids compared with those irrigated with the same volume of water. The lowest temperature in the bark media irrigated with ice cubes was ≈11 °C, while controlled freezing experiments showed that damage to photosystem II in orchid roots did not occur until bath temperatures were below −7 °C. The internal temperature of roots in direct contact with ice cubes decreased to around 4 °C. Ice cube irrigation had no detrimental effects on the quality or display life of potted Phalaenopsis orchids growing in bark, demonstrating that ice cubes are a viable method of irrigating these tropical house plants.
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