Limitations in the Valorization of Food Waste as Fertilizer: Cytogenotoxicity Assessment of Apple and Tomato Juices By-Products

Apples and tomatoes are among the most consumed products all over the world, as well as the natural juices prepared from each of them. The large quantities of resulting by-products should be reused in various directions within the circular economy. In this study, apple and tomato pomaces were tested as potential biofertilizers for agricultural crops. To this end, aqueous extracts of apple pomace and tomato pomace were prepared in two concentrations (0.05% and 0.5%) and used to treat wheat caryopses and sprouts. The following were evaluated: mitotic index, genotoxic index, caryopses germination rate, and wheat sprout growth. The biotic response of wheat to treatments with the apple and tomato pomace extracts consisted of reduced mitotic activity, i.e., cytotoxicity, and the formation of genetic abnormalities, i.e., genotoxicity. The cytotoxicity and the genotoxicity were reflected at the macro level in phytotoxic effects, manifested by a reduction in the germination rate of caryopses and a decrease in the length of wheat roots and shoots. Physiological parameters were positively correlated with the mitotic index and negatively correlated with the genotoxic index. The obtained results point us not to recommend the use of unprocessed apple and tomato pomaces as biofertilizers, but, on the contrary, as bioherbicides.