Lettuce transplants production using a posidonia based compost as growing substrate

Posidonia (Posidonia oceanica [L.] Delile) is a marine phanerogam endemic of the Mediterranean basin. Senescent plant parts periodically detach from and accumulate along Mediterranean beaches, forcing the coastal municipalities to remove and manage somehow the large amount of beached biomass. In this research, a posidonia based compost (posidonia, 63% by volume - olive tree pruning residues, 21% - green waste, 16%) has been used as growing media component at different ratios (0, 25, 50, 75 and 100%), as a complement to a peat based commercial substrate, for nursery lettuce seedlings production. Growing media with increasing compost percentage showed higher pH, EC, air capacity and nutrients availability, but lower water holding capacity. The overall growth of the seedlings was enhanced by the compost presence in the substrate, with positively evidences for both roots and leaves. Posidonia based compost could represent an interesting alternative to peat as horticultural growing media component.