Cultivation of barley seedlings in a coffee silverskin-enriched soil: effects in plants and in soil

Aims Coffee silverskin (CS) is the most abundant waste from coffee roasting. In this research, the potential of CS as soil fertilizer for barley (Hordeum vulgare L.) cultivation was evaluated. Methods Barley plants were grown, for 10 days from the start of germination, in soils mixed with different CS percentages (0, 2, 6 or 10%). The effects of CS addition on soil capacity to retain water and on the mold/yeast community were evaluated. Physiomorphological and biochemical responses of leaves and roots of barley plants growing in CS-enriched soil were evaluated. Results Root and shoot length decreased in plants grown with CS, but biomass was less affected and even increased at 2% CS. Photosynthesis was higher in barley seedlings grown on CS-enriched soil than in control plants. However, Chl b was reduced in leaves of plants grown with CS. The total leaf protein content did not change with moderate CS additions in soil. However, when grown in soil with 10% CS, a significant reduction of total protein and Rubisco was observed. Extracts of barley shoots from plants grown in soil with 10% CS showed a greater antioxidant capacity with respect to all other experimental conditions. Conclusions We conclude that CS addition to soil may improve soil property to retain water and, at low concentrations (2% w/w) positively affects barley physiology and growth.