Abstract:In order to investigate the photoprotection mechanism in young leaves of dominant tree species of subtropical forest in summer, three mid-successional species, i.e. Schima superba, Castanopsis fissa and C. chinensis, and three late-successional species, i.e. Machilus chinensis, Cryptocarya chinensis and C. concinna, grown on 100% (FL) and 30% (LL) of full sunlight, respectively, the leaf phenotype, anthocyanins content, photosynthetic pigment content, antioxidant capacity, flavonoids content, phenols content and restoration efficiency of the maximum photochemical efficiency (Fv/Fm) of young or mature leaves of six dominant trees were analyzed. The results showed that young leaves of dominant tree species at two successional stages had lower chlorophyll content (Chl a+b) and Chl a/b than mature leaves, but light protects substances were more than mature leaves. Young leaves of mid-successional species exhibited higher anthocyanins content and total antioxidant capacity (TCA) but lower contents of flavonoids and total phenols than those in late-successional species. Young leaves of both successional species grown in FL demonstrated higher contents of anthocyanins, phenols, flavonoids, TCA and restoration capability of Fv/Fm than those grown in LL. In addition, Fv/Fm of young leaves with anthocyanins restored faster after exposed to weak light. Therefore, it was suggested that photosynthetic capacity is negative correlated with photoprotection potential. Anthocyanins play an important role in photoprotection of young leaves in mid-successional species, whereas young leaves of late-successional species are mainly photoprotected by antioxidant compounds (flavonoids, total phenols).
