Growth and Physiological Responses of Three Landscape Plants to Calcium Chloride

The objective of this study was to analyze the effects of calcium chloride (CaCl2) used as a de-icing agent on growth and physiological responses of three ground cover plants, Hosta longipes, Iris ensata, and Iris pseudacorus. CaCl2 concentration was set to be 0 mM (control), 9 mM (0.1%), 18 mM (0.2%), and 54 mM (0.6%). After treatment with CaCl2 for 3 months, plant heights, fresh weights of shoots and roots, photosynthetic rates, chlorophyll fluorescence, chlorophyll content (SPAD), and leaf water potential were measured. After Hosta longipes was treated with CaCl2 for 60 days, physiological damage began to occur in all treatment groups except for the control group. Those treated with 54 mM CaCl2 completely withered. At 90 days after treatment (DAT), there were significant differences for all measured parameters for Hosta longipes compared to the control (p < 0.001). The higher the treatment concentration, the lower the photosynthetic rate, the SPAD, and the leaf water potential. There was no significant difference in plant height in Iris ensata after 60 DAT (p > 0.05), but in other physiological responses, there was a significant difference by concentration (p < 0.001). Iris ensata had a visually healthier state at 90 DAT, showing the smallest reduction in photosynthetic rate at 60 DAT and 90 DAT. Its SPAD value was increased more at 90 DAT than at 60 DAT, indicating its higher resistance to CaCl2. Iris pseudacorus showed similar results as Iris ensata. Over time, the 54 mM treatment resulted in significant damage. Among these three plants, Iris ensata showed the highest tolerance to CaCl2. Therefore, they are considered to be highly beneficial ground cover plants for green infrastructure in urban areas with high CaCl2 concentrations.