Sustainable Fertilization with Ramial Chipped Wood Enhances Antioxidant Profiles in Tomato Varieties: An Untargeted Metabolomics Approach

Tomatoes are among the most consumed vegetables within the Mediterranean diet, recognized as one of the healthiest dietary patterns in the world. This study evaluated the effects of four fertilization treatments on the antioxidant and metabolic profiles of four local tomato varieties: Cornabel (V1), Cuban Pepper (V2), Corno Andino (V3), and Roli Rosa (V4). Treatment 1 (T1) used 1.28 kg/m² of commercial woody compost (C/N ratio 13), while Treatment 2 (T2) served as the control, initially without fertilization. Treatments 3 and 4 (T3, T4) incorporated ramial chipped wood (RCW) at 15 kg/m² and 7.5 kg/m², respectively, without tillage. Each treatment × variety combination included four biological replicates (<i>n</i> = 4). Untargeted metabolomic profiling via UHPLC-QToF and statistical analyses identified 163 compounds, 37 of which showed significant varietal differences (<i>p</i> < 0.05). The flavonoid eriodictyol was more abundant in the Pebroter varieties (V1, V2, V3), whereas luteolin-8-<i>O</i>-glucoside (orientin) predominated in V4, likely due to differential expression of biosynthetic genes. RCW (T3) yielded higher levels of antioxidant compounds like phenolic acids, and flavonoids compared to compost and control; however, no dose-response was observed using different doses of RCW (T3 and T4). These findings demonstrate that RCW may modulate the antioxidant metabolite profile of tomatoes, highlighting its potential as a sustainable fertilization strategy for enhancing antioxidant compounds.