Low substrate water content is efficient for the performance of Ficus pumila ‘Variegata’ indoors

This study investigated how the substrate volumetric water content (VWC) and fluctuating irrigation affect the growth and performance of variegated Ficus pumila ‘Variegata’ indoors using a soil moisture sensor based-automated irrigation system. The irrigation treatments consisted of three treatments maintaining a constant VWC (at 0.20, 0.40, and 0.60 m³·m^-3) and one treatment with a fluctuating VWC (threshold, 0.20 m³·m^-3; 0.20 F). Plant shoot growth, chlorophyll content, leaf variegation, and coloration parameters were measured at four weeks after treatment. The 0.20 and 0.20 F treatment groups had lower shoot fresh weight than the groups maintained at higher VWC thresholds. Although the 0.40 and 0.20 F treatments had similar average VWCs during the experiment, the 0.20 F group had less shoot growth than the 0.40 group, resulting in a lower irrigation amount. Physiological responses, such as leaf relative water content and F _v/F _m, were not affected by irrigation treatment. Similarly, leaf variegation and coloration were not influenced by the irrigation treatments. A higher irrigation amount was required to maintain the 0.60 treatment group compared to the 0.40 treatment group, even though there were no significant differences in growth parameters between the groups. In contrast, plants in the 20 F treatment group had high water use efficiency, as they had proper growth with low irrigation amounts. Overall, maintaining a low water content or providing intermittent irrigation at 0.20 m³·m^-3 provided a slow growth of F. pumila ‘Variegata’ indoors, resulting in adequate plant performance and ease of management for house plants.