Low and constant substrate moisture maintains quality and improves water use efficiency in indoor poinsettia

초록

Indoor ornamental plants are widely used in residential and commercial environments, yet irrigation guidelines for indoor conditions remain limited. Poinsettia (Euphorbia pulcherrima 'Prestige Red') is one of the most widely used potted ornamental plants for indoor decoration, and its post-production quality is strongly influenced by water management. This study evaluated whether a sensor-based irrigation strategy maintaining low but stable substrate volumetric water content (VWC) could maintain poinsettia performance during post-production indoor maintenance while improving irrigation efficiency. Plants were grown under controlled indoor conditions and subjected to four irrigation treatments: constant VWC at 0.2 or 0.5 m & sup3;& centerdot;m(-)& sup3; (0.2C, 0.5C) and fluctuating irrigation triggered below 0.2 or 0.5 m & sup3;& centerdot;m(-)& sup3; (0.2F, 0.5F). Growth parameters, physiological traits, ornamental quality, and water use efficiency (WUE) were evaluated over six weeks. Growth, bract development, compactness, and leaf relative water content were not affected by irrigation treatment (P > 0.05), indicating that poinsettia quality was maintained even under substantially reduced substrate VWC. Relative chlorophyll content and maximum quantum yield of PSII remained within optimal ranges, demonstrating that low VWC did not impair photosynthetic integrity. In contrast, total irrigation amount and WUE were strongly dependent on irrigation management. The constant low-VWC treatment (0.2C) reduced irrigation amount and achieved the highest WUE (P < 0.001). These results demonstrate that maintaining a low and stable VWC level using sensor-based irrigation can substantially reduce water use without compromising the ornamental quality of indoor poinsettia and provide a management strategy for sustainable indoor irrigation management.

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