Growth and Yield Characteristics and Heavy Metal Content on Tomatoes Grown in Different Growing Media

Summary

This study evaluated the use of compost and beached Posidonia oceanica seaweed as alternative hydroponic growing media for greenhouse tomatoes, comparing them to a commercial pumice substrate control. Although compost contained higher total heavy metal concentrations than the seaweed or control, organic matter in the compost limited plant uptake, resulting in comparable metal levels in tomato fruits and leaves across all treatments. The findings suggest that these waste-derived alternative media can be used without accumulating metals in the edible crop, potentially offering a sustainable re-use pathway for abundant Mediterranean seaweed deposits.

Regional applicability

This study was conducted in Italy with Mediterranean seaweed, so findings on beached Posidonia oceanica are regionally specific to southern European coastal areas. However, the broader principle—that organic matter can sorb heavy metals and limit plant bioavailability—has application to UK horticultural practice; UK growers using compost-based media would benefit from similar chemical characterisation to ensure food safety.

Key measures

Plant growth parameters, yield, total concentrations of Pb, Cd, Zn, Cr, Cu in growing media, tomato fruits, and leaves

Outcomes reported

The study measured growth, yield parameters, and total concentrations of heavy metals (lead, cadmium, zinc, chromium, copper) in tomato fruits, leaves, and growing media across three substrate types. It assessed whether alternative growing media (compost and beached Posidonia oceanica) posed food safety risks through metal accumulation.

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