Sugar-to-acid ratio. (a) Mean sugar-to-organic acid ratio of 16 tomato cultivars during 2015 and 2016 in order of ascending fruit weight. Cocktail tomato (left block), salad tomato (centre), and beefsteak tomato (right). (b) Mean sugar-to-organic acid ratio of F6 breeding lines of the cross Resi × Phantasia F1 and of both parents during 2015 and 2016 in order of ascending fruit weight. Means followed by a common letter are not significantly different at the 5% level in the Tukey test; in (a), the test was performed within each panel.