Light is the main source for plants to obtain energy.Asarum forbesii is a typical shade medicinal plant, which generally grows in the shady and wet place under the bushes or beside the ditches.It can grow and develop without too much light intensity.This experiment explores the effects of shading on the growth, physiological characteristics and energy metabolism of A.forbesii, which can provide reference and guidance for its artificial planting.In this experiment, A.forbesii was planted under 80%, 60%, 40%, 20% and no shade.During the vigorous growth period, the photosynthetic physiological characteristics such as fluorescence parameters, photosynthetic parameters, photosynthetic pigment content and ultrastructure, as well as the content of mitochondrial electron transport chain(ETC) synthase and nutrients were measured.The results showed that the photosynthetic pigment content, chlorophyll fluorescence parameters and net photosynthesis rate(P_n) decreased with the decrease of shading.Under 20%-40% shading treatment, the plants had damaged ultrastructure, expanded and disintegrated chloroplast, disordered stroma lamella and grana lamella, and increased osmiophi-lic granules and starch granules.The activities of nicotinamide adenine dinucleotide dehydrogenase(NADH), succinate dehydrogenase(SDH), cytochrome C oxidoreductase(CCO) and adenosine triphosphate(ATP) synthasewere positively related to light intensity.With the reduction of shading, the content of total sugar and protein in nutrients increased first and then decreased, and the content was the highest under 60% shade.In conclusion, under 60%-80% shading treatment, the chloroplast and mitochondria had more complete structure, faster energy metabolism, higher light energy-conversion efficiency, better absorption and utilization of light energy and more nutrient synthesis, which was more suitable for the growth and development of A.forbesii.
Keywords: Asarum forbesii; energy metabolism; photosynthetic physiology; shade.