Responses of Growth and Photosynthesis in Potted Radermachera hainanensis and R. sinica to Various Medium Water Contents

Abstract Radermachera hainanensis Merr. and R. sinica Hemsl. are woody ornamental plants commonly used for indoor or landscape purposes. However, there is currently a lack of information regarding their water management. Potted plants of these two species were subjected to four volumetric water content (VWC) treatments: 20% VWC (dry), 20%/60% VWC (dry/wet cycle), 40% VWC (moisture), and 70% VWC (waterlogging). Results revealed that both Radermachera species exhibited the poorest growth under the 20% VWC treatment, with the lowest stem diameter, leaf area, plant dry weight, net photosynthetic rate ( Pn ), stomatal conductance, and maximum quantum efficiency of photosystem II (Fv/Fm). The maximum stem diameter, leaf area, and root dry weight were recorded with the 40% VWC treatment. Stem diameter, leaf area, Pn , and Fv/Fm were higher in both Radermachera species with the 20%/60% VWC compared to the 20% VWC treatment. R. sinica exposed to 20%/60% VWC exhibited similar root dry weight and leaf drop as those with the 40% VWC treatment, while R. hainanensis showed lower root dry weight and higher leaf drop compared to the 40% VWC. Root dry weight, Pn , and Fv/Fm remained unchanged in R. sinica but reduced in R. hainanensis with the 70% VWC compared to the 40% VWC. Species used in this study: Golden jasmine tree, Radermachera hainanensis Merr.; China Doll, Radermachera sinica Hemsl.