Impact of water regime, nitrogen supply and location on quality and nutritional composition in a tomato diversity panel in organic cultivation

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• Investigated the effects of nitrogen and water stress on the accumulation of mineral and metabolites in tomato. • Two environments and organic farming conditions considered. • Water deficit increase the levels sugars, ascorbic and citric acid. • Flavonoids increase under water stress whilst lowering under nitrogen deficit. • Carotenoids highly influence by growing site conditions. • Explained the model of G x E underpinning the accumulation of bioactive compounds in tomato. Increasing productivity and quality in tomato ( Solanum lycopersicum ) is a key challenge in sustainable horticulture, given its high input requirements and the need to optimize resource use efficiency. In consequence, there is a pressing need to identify cultivars adapted to in low-input environments. In the present study, a diversity panel of twenty-five genotypes was tested for agronomic performance, mineral fruit composition and main primary and secondary metabolites in two organic farms located in Italy and Spain. Three treatments were applied including standard cultivation conditions (control), lack of nitrogen input, and water deficit (70 % of reduction). Overall, in both sites, an increase of sugars, ascorbic and citric acid was found under water deficit whereas malic acid tended to be higher under nitrogen deprivation. Flavonoids concentration showed a robust increase in drought stress conditions, whilst it decreased under nitrogen deprivation. Carotenoids showed opposite trends in the two environments with a lower accumulation in both stressed trials in Italy and increases in Spain in particular under water deficit. The analysis of genotypic (G), location (L), and treatment (T) factors revealed a high proportion of variance attributed to G × T for primary and secondary metabolites, whereas minerals were more influenced by G × L and T × L interaction. In addition, no significant impacts of L and T on ascorbic acid, potassium and manganese contents were found. These findings provide valuable insights to improve tomato quality and further enhance breeding for resilience, particularly for low-input and organic conditions.