MICROPROPAGATION OF MATURE PLATANUS × HISPANICA TREES BY AXILLARY SHOOT PROLIFERATION

A protocol for vegetative propagation by organogenesis has been developed for several anthracnose tolerant Platanus A— hispanica mature trees. Different types of putative juvenile and mature plant materials were used. From them apical and nodal explants were tested to initiate cultures. Nodal explants from well-developed epicormic shoots, flushed from pieces of branches, gave low contamination percentages and 42% of established explants. Newly formed shoots were multiplied in MS medium supplemented with 1.33 µM BAP and 0.27 µM NAA. The effect of using both gelled and liquid medium was tested. Multiplication rate was highly dependent on genotype. The highest multiplication rate was obtained on gelled medium (4 new shoots per explants each 8 weeks). Microshoots were rooted on a MS gelled medium with macronutrients at half, reduced sucrose and supplemented with 0.49 µM IBA. Rooting ranged between 30 and 80% depending on genotype. Two major problems in the micropropagation of Spanish plane trees were observed: leaf and shoot tip necrosis, and low plantlet survival during acclimatisation. Overall, losses of explants in proliferation due to necrosis were more pronounced in liquid medium (69%) than on solid medium (57%). Only a very few plants could be acclimatised.