Effect of Differential Light Quality on Morphology, Photosynthesis, and Antioxidant Enzyme Activity in Camptotheca acuminata Seedlings

Light quality is an important environmental factor for plant growth and development. In this study, the effects of light quality (white, blue, yellow, and red light) on plant growth, photosynthesis, and radical oxygen species production and scavenging were investigated, in Camptotheca acuminata (C. acuminata) seedlings, by means of measuring growth parameters, photosynthetic pigments, gas exchange, and chlorophyll fluorescence, as well as stomatal structure and density, chloroplast ultrastructure, and ROS contents and antioxidant activities. Compared with white light, red light significantly increased seedling height, shoot, and total plant biomass, and promoted the highest photosynthetic capacity, electron transport, and photochemical efficiency. Red light also helped facilitate leaf development, indicated by higher total and specific leaf area, as well as decreased malondialdehyde content and relative electrolyte conductivity and contents of superoxide anion production rate and peroxide. In contrast, blue and yellow light significantly reduced plant growth, and increased activities of superoxidase dismutase, peroxidase, and catalase. Furthermore, red light promoted chloroplast development, which enhanced photosynthetic efficiency. These results suggest that red light could improve plant growth in C. acuminata seedlings through activating photosynthetic processes, reducing ROS accumulation, and maintaining chloroplast structure.