Impact of substrate depth and fertilizer type on growth, production, quality characteristics and heavy metal contamination of tomato and lettuce grown on urban green roofs

Panayiotis A. Nektarios, Dimitris Ischyropoulos, Panagiotis Kalozoumis, Dimitrios Savvas, Dionisios Yfantopoulos, Nikolaos Ntoulas, Georgios Tsaniklidis, Eleni Goumenaki