Performance of Navel orange trees grafted onto two new dwarfing rootstocks (Forner-Alcaide 517 and Forner-Alcaide 418)

•The aim of the present work was to study the performance of two new dwarfing citrus rootstocks (Forner-Alcaide 517 and Forner-Alcaide 418) in comparison with Carrizo citrange.•Forner-Alcaide 418, lower hydraulic conductance was related to a smaller lumen area of root xylem vessels with respect to the other rootstocks.•The graft union may provide resistance to sucrose transport in dwarfing rootstocks, as indicated by the reduced translocation of 13C-labelled photoassimilates from leaves to roots and reduced soluble sugar and starch concentrations under the graft union.•Plants on both dwarfing rootstocks showed decreased translocation of 13C-photoassimilates to roots, possibly contributing to higher availability of these compounds in the scion, and resulting in increased 13C transport towards the fruits. This effect could explain the higher yield efficiencies found in dwarfing rootstocks.•The performance of two new dwarfing citrus rootstocks has been studied. The graft union may provide resistance to sucrose transport in dwarfing rootstocks. Plants on dwarfing rootstocks showed decreased translocation of 13C-photoassimilates to roots.