Genotype and cluster position influence carotenoid and mineral profiles of mini plum tomatoes in response to zinc biofortification and triacontanol application

The present experiment investigated the response of mini plum tomatoes ‘Angelle’ (red fruit) and ‘Dolcenera’ (brownish fruit) to foliar applications of Zn-EDTA (1.7 mmol L−1) and triacontanol (11.4 μmol L−1, TRIA), applied either alone or in combination, in terms of carpometric traits, carotenoid and mineral profiles determined on second (CII) and sixth (CVI) clusters. (all- E)-Lycopene was higher and stable across clusters in ‘Angelle’ (2009 μg 100 g−1 FW, on average), whereas ‘Dolcenera’ showed higher concentrations of (all- E)-β-carotene and lutein (on average 793 and 92 μg 100 g−1 FW, respectively), although both decreased from CII to CVI (−30% and −38%, respectively). Compared to control, both TRIA-based treatments promoted the accumulation of (all- E)-lycopene (+20%), (all- E)-β-carotene (+9%, on average), and total carotenoids (+15%) in fruits, with stronger effects in ‘Angelle’. ‘Dolcenera’ also showed higher concentrations of fruit macrominerals (except Ca), while Zn-EDTA application, either alone or combined with TRIA, produced the strongest effects on fruit mineral composition, increasing Zn concentration (+67%, on average) and reducing its variability between clusters. Overall, the results indicate that foliar applications of triacontanol promote carotenoid accumulation in mini plum tomatoes, whereas Zn-EDTA enhances the Zn concentration and stabilizes its levels across clusters. These findings suggest that combining cultivar diversification, including the brownish mini plum typologies, with targeted foliar applications of triacontanol and Zn-EDTA may represent a viable strategy to modulate carotenoid and mineral composition while maintaining a more consistent nutritional profile of greenhouse mini plum tomatoes over the harvest season.