The present work aimed to establish a protocol for the micropropagation of pear rootstock Pyrus calleryana D-6. Explants were excised from mother plants, disinfected with alcohol 70% (2 minutes), sodium hypocloride 1.5% and Tween 20 (10 drops L-1) during 20 minutes. The explants were transferred to MS medium supplemented with BAP (4.4 µM), GA3 (0.3 µM) and NAA (0.05 µM). For the multiplication phase the microcuttings (2-3 buds) were transferred to flasks containing 50 mL of MS and MS1 [culture media modified (NH4NO3)/2 and 2x(CaCl2.2H2O) ] media. These media were supplemented with sucrose (30 gL-1), ágar (7 gL-1) and BAP (0 and 6.7 µM), IBA (0 and 0.5 µM) and GA3 (0 and 0.3µM). In the 'double-phase' system (liquid gelling) 10 mL growth regulators free of MS liquid medium were added to the flasks, after 30 days, and the treatments were evaluated 60 days of in vitro culture. The results showed that 23.5% of the explants presented proliferation. The main constraint for the in vitro establishment was the oxidation that impaired 44.8% of the explants. The 'double-phase' culture system demonstrated to be effective for in vitro multiplication. The largest multiplication factor (16.8 shoots/explant) and the largest length of the shoots (33mm) were obtained in MS medium containing BAP (6.7µM) and IBA (0.5µM).
Pear plant; rootstock; culture medium; micropropagation
