Growth, Leaf Pigment Content, and Antioxidant Potential of Ferns Grown in Peat Substrate Amended with Camelina Press Cake

Using natural waste as a source of minerals and biostimulants can offer many advantages in the production of plants in containers. The research aimed to evaluate the usefulness of cakes obtained from the production of camelina seed oil (Camelina sativa) in the cultivation of ferns. The greenhouse experiment used ornamental ferns rich in health-promoting compounds: Onoclea sensibilis, Polypodium vulgare, and Polystichum polyblepharum. Plants were planted in pots filled with peat substrate mixed with camelina press cake in the form of pellets at a dose of 1 g/L or 5 g/L. Plants grown in 100% peat substrate constituted the control. It was found that the plants grown in the medium enriched with press cake were higher (P. vulgare and P. polyblepharum), wider (O. sensibilis and P. polyblepharum), and had increased dry weight (O. sensibilis and P. polyblepharum) regardless of the dose of the cake. Moreover, in all species, the addition of press cake significantly increased total chlorophyll content by 23.5–32.5% and carotenoids by 17.7–68.7% compared to the control. The effect of cake on the level of total polyphenols and flavonoids as well as antioxidant activity was unequal and depended mainly on the species and the waste dose. Overall, developing sustainable fern cultivation principles and understanding their nutritional properties could contribute to the broader use of ferns in green spaces, medicine, pharmaceuticals, and cosmetics.