Species-Specific Coloration Responses of Colored-Leaf Plants to High and Low Light: A Case Study of Seven Common Garden Plants in South China

Abstract

Leaf coloration in colored-leaf plants is regulated by light intensity, but the response modes differ among species, directly affecting light-environment design in garden configuration. In this study, seven common colored-leaf plants from the subtropical region of South China, Excoecaria cochinchinensis, Tradescantia spathacea, Coleus scutellarioides, Celosia cristata, Jacobaea maritima, Loropetalum chinense var. rubrum, and Cordyline fruticosa ‘Aichiaka’, were used as materials. Four treatments were established: full light (100% light transmittance), 60% light transmittance, 40% light transmittance, and 20% light transmittance. After 6 weeks of treatment, leaf RHSCC (Royal Horticultural Society Colour Chart) color codes, anthocyanin content, and the maximum photochemical efficiency of PSII (Fv/Fm) were measured. The results showed that the coloration responses of the seven colored-leaf plants could be divided into three types: high-light-coloration type, low-light-coloration type, and light-intensity-insensitive type. Among them, the high-light-coloration type included C. scutellarioides, C. cristata, and T. spathacea; their anthocyanin contents under full light and 60% light transmittance were higher than under low-light treatments, and their RHSCC color codes tended toward purple-red under high light and purple-red-green under low light. The low-light-coloration type included Loropetalum chinense var. rubrum and C. fruticosa ‘Aichiaka’; their anthocyanin contents were highest under 60% or lower light transmittance, and their RHSCC color codes tended toward purple-red under low light and cyan-green under high light. The light-intensity-insensitive type included J. maritima and E. cochinchinensis; their RHSCC color codes and anthocyanin contents differed little among different light intensities, and the silvery white color of Jacobaea maritima was mainly determined by epidermal trichome structure. Fv/Fm decreased under high light or full light in species mostly belonging to the high-light-coloration type, whereas species whose Fv/Fm remained stable near 0.8 under all light intensities mostly belonged to the low-light-coloration type or the light-intensity-insensitive type. The study indicates that garden configuration of colored-leaf plants should design light environments according to coloration response type rather than the unified label of “colored-leaf plants.”