Experiments on apple micropropagation were carried out in the laboratories of the Instituto Agronômico, Campinas, Brazil. The main hormonal requirements of shoots in the different development phases - growing, proliferation, root induction and effective root and shoot development - were studied in five apple cultivars: Rainha, Gala and the selections IAC 1381-22, IAC 3881-8 and IAC 4881-11. The best technique for apple micropropagation in our conditions was found to consist of: a) growth of meristems in Murashige and Skoog saline solution culture medium supplemented with 1.0mg/liter thiamin HCl, 0.25mg/liter nicotinic acid, 100mg/liter myo-inositol, 6.5g/liter agar, 30g/liter sucrose and 7.5µM BAP (6-benzylaminopurine); b) transfer to dark room for 5 days in a root induction medium containing the same mineral and organic constituents of the first solution, only changing BAP for 2.0µM IBA (indole-3-butiric acid); and c) transfer to a root growth medium basically equal to the other except that no phytohormones was added. The rooted plantlets were potted in vermiculite, watered with a dilute mineral solution and kept in a growth chamber under high moisture for 15 days; finally they were potted in a soil mixture and transferred to a greenhouse.
apple, Malus spp.; meristem culture; in vitro rooting; explant; shoots; BAP; IBA