Developing patterns in Prunus laurocerasus grown on sediment enriched substrates

Purpose: Intensive horticulture relies on non-renewable materials and creates high environmental concern due to peat overexploitation and long-distance transportation. Emerging research is therefore looking for alternative growing media. The aim of this study was to demonstrate the possibility of converting waste (dredged sediment) into a product (commercial substrate) through sustainable techniques. Methods: Sediments from the Leghorn port (Italy) were subjected to phytoremediation and landfarming before use for cultivation. Blends of treated sediment (0, 25, 50%) with standard substrates based on peat, pumice, coconut fibre, and wood fibre were used for the propagation of cherry laurel (Prunus laurocerasus) using rooted cuttings in a greenhouse and with different water regimes. Growing media were analysed just after mixing their constituents, before plant cultivation, and cherry laurel vegetative growth and physiological parameters were studied. Results: The phytoremediated sediment was successfully used as growth medium constituent in all tested media other than peat and coconut fibre in proportions varying between 25 and 50%, whereas in combination with wood fibre, it reduced cherry laurel growth and aboveground biomass. Leaf chlorophyll content and lipid peroxidation did not differ regardless of substrate mixture and water regime. Discussion: All sediment-based media showed physicochemical parameters and heavy metal content in line with Italian regulations. Although sediment-based substrates were rich in zinc, this element was found at very low concentrations in plants. Our results highlight that the treated sediment can be used as a partial substitute for standard raw materials, especially peat and coconut fibre, in container production of cherry laurel.