In vitro propagation of avocado (Persea drymifolia Ness.)

In the past 20 years, reports on micropropagation and rooting in vitro of avocado shoots, with diverse origins and treatments, have been published. However, none of them reached the level required for large scale propagation of the species. It is considered that, in the first place, the micropropagation of avocado requires an efficient system of rooting. Therefore, a system to induce the rooting in vitro of avocado shoots, based on indole-3-butyric acid (IBA) pulses and some treatments based on thidiazuron (TDZ) was tested, using 40 explants per treatment. The treatments with TDZ did not succeed in rooting shoots. Some treatments with pulses of IBA induced the following rooting results: without growth regulators, 16%; 4,000 mg L-1 of IBA for 5 seconds, 8.3% rooted; 100 mg L-1 for 72 hours, 20%; 50 mg L-1 for 72 hours, 15.4%; 150 mg L-1 for 24 hours, 5% rooted. It is considered possible to improve these results by adjusting the range of IBA concentrations as well as in the time range of pulse applications. Finally, it is easier to establish in vitro explants derived from mature seeds or embryos germinated in vitro. (author)