EFFICIENT IN VITRO PROPAGATION AND ROOTING OF ADULT EXPLANTS OF CITRUS ROOTSTOCKS

The influence of the basal medium and different plant growth regulators on the efficient micropropagation of nodal explants from mature trees of sour orange and ‘Cleopatra’ mandarin citrus rootstocks was studied. The preference of the two citrus rootstock shoot cultures for high-salt media, like MS or DKW, was observed. Several combinations of BA and AD, KIN or GA were made in an attempt to optimize the proliferation phase. The addition of BA and AD to the culture medium improved the proliferation in sour orange or ‘Cleopatra’ mandarin in the same way as BA/GA. The use of different combinations of BA/KIN did not improve any of the studied variables. The transfer of in vitro shoots to rooting media, containing different concentrations of IBA and IAA, produced complete plantlets of ‘Cleopatra’ mandarin, but very low rooting percentages in sour orange were obtained. To improve the rooting results, different combinations of NAA and IBA were tested and higher rooting percentages than in the IBA/IAA combinations were produced. In sour orange nearly 100% of rooted explants were obtained.