Response of total phenols, flavonoids, minerals, and amino acids of four edible fern species to four shading treatments.

Total phenols, flavonoids, minerals and amino acids content were investigated in leaves of four fern species grown under four shading treatments with different sunlight transmittance in 35% full sunlight (FS), 13% FS, 8% FS and 4% FS. The leaves of four fern species contain high levels of total phenols and flavonoids, abundant minerals and amino acids, and these all were strongly affected by transmittance. Total phenols and flavonoids content were significantly positively correlated with transmittance, while minerals and total amino acids content were significantly negatively correlated with transmittance, a finding that supports research into how higher light intensity can stimulate the synthesis of phenols and flavonoids, and proper shading can stimulate the accumulation of minerals and amino acids. (L.) Todaro (MS) had the highest total phenols content, (Doll.) Ching (AM) showed the highest total amino acids, total essential amino acids content, (L) var. Fernald (OCA) exhibited the highest total non-essential amino acids and flavonoids content. (L.) Kuhn var. (Desy.) Underw. ex Heller (PAL) exhibited the highest minerals content. This research can provide a scientific basis for the cultivation and management of those four fern species.