The Effect of Scion/Rootstock Combination and Ripening Stage on the Composition of Carotenoids and some Carpometric Characteristics of Tomato Fruit

In this study, the impact of scion/rootstock combinations on the composition of carotenoids and fruit firmness during three ripening stages was investigated. Two tomato cultivars were assessed as scions: 'Amati F1', and 'Gardel F1', grafted on two rootstocks: 'Body F1' and 'Robusta F1'. To evaluate the effect of grafting and ripening stages on firmness and colour evolution of tomato fruits, the lightness coefficient L* and a*/b* index were monitored in tomatoes, harvested at technological ripening stages (orange to light red and red). The effect of scion/rootstock combinations on the coloration of fruits was more pronounced than on the firmness of fruits. Significantly lower a*/b* ratio and higher L* values were measured on fruits from 'Body F1' rootstock, which could indicate slower ripening compared to 'Robusta F1' rootstock and non-grafted plants. Fruit firmness was only significantly affected by the scion cultivars and ripening stages. In tomato fruit, three carotenoids were detected; lycopene represented the major, beta-carotene the second prevailing and lutein the minor carotenoid. Grafting significantly affected the composition of carotenoids in fruits of 'Amati F1' scion, where a significant increase of lycopene and a decrease of beta-carotene were measured in fruits correlated with a change from orange to red colour. The composition of carotenoids in tomato fruit is usually under genetic control, which was confirmed also in our study. However, our results also indicate that the levels of carotenoids and their composition can additionally be affected by scion/rootstock regulation and ripening stages.