STEM CUTTING AND AIR LAYERING OF Tibouchina fothergillae (D.C.) Cogn. (MELASTOMATACEAE)WITH THE APPLICATION OF NAPHTHALENE ACETIC ACID

Abstract

Tibouchina fothergillae is a Brazilian native species with ornamental potential and adequate for ecosystems rehabilitation. However, the species has very small seeds, hard to collect by conventional methods, making large scale seed propagation not commercially feasible. The aim of this work was to propagate T. fothergillae by stem cuttings and air layering, with application of naphthalene acetic acid. Samples were obtained from plants located at the Campus III of the Federal University of Parana (UFPR), in Curitiba-PR-Brazil. Both experiments were installed in August, 2006 and evaluated after 20 days (stem cutting) or 76 days (air layering). The concentrations of 0, 500, and 1000 mg kg^-1 of naphthalene acetic acid (NAA) were applied in powder in the cuttings and in vaseline paste in the layerings. It was observed 100% of rooting on stem cuttings. The averages of roots per cutting treated with NAA (20.88 and 21.88) were higher than the control’s average (10.58). However, there weren’t differences of the root length among treatments (grand mean= 3.35 cm). On the air layering experiment, rooting varied from 50 to 100%. The 1000 mg kg^-1 NAA treatment promoted the largest number of roots per layering (17.00) and higher root length mean (11.73 cm). Through these results, both techniques can be considered suitable for T. fothergillae’s propagation. It’s recommended to use NAA (1000 mg kg^-1) to increase the number of roots on air layerings. NAA application isn’t necessary for stem cuttings.