LAUSR

Abstract The intensification of horticultural crops cultivation makes urgent the seeking for alternative growth substrates that could substitute non-renewable and/or synthetic growing media, such as peat and rock wool. The aim of the present study was to evaluate the potential use of byproducts from two industrial crops commonly cultivated in the Mediterranean basin, namely cardoon and cotton, as growth substrates for Cichorium spinosum, while zeolite addition was also tested as a soil amendment. A pot experiment was carried for two consecutive growing periods and plant growth was evaluated for six growing media compositions, while plant extracts were also evaluated in terms of their phenolic compounds profile, antioxidant and antimicrobial activities. The results of this study showed that cotton byproducts and zeolite may partially substitute peat in growth substrate of C. spinosum and high yields comparable to peat may be achieved. Phenolic compounds content and antioxidant activity of leaves' extracts was higher for plants grown in soil which showed severe stress symptoms comparing to the other tested substrate blends. Antimicrobial activity was also affected by growth substrate composition, only in the case of antibacterial properties of leaves' extracts, whereas none of the extracts presented significant antifungal activities. In conclusion, the use of cotton ginning byproducts and zeolite in growth substrate blends may partially substitute conventional substrates as peat in horticultural crops production, resulting in reduction of production cost and lessening of bulky byproducts’ management and related environmental burden without compromising yield.