Rooting of Azalea Cuttings (Rhododendron x simsii Planch.) Under Indolebutyric Acid and Boron Concentrations

Azalea plants produce flowers of different colors, and are one of the most cultivated ornamental plants. Their propagation is performed mainly by cuttings, but it still results in low commercial return. The objective of this study was to evaluate the indolebutyric acid and boron influence on the rooting of cuttings of two azalea varieties. One produces white flowers, while the other produces pink ones. Softwood cuttings were treated with five concentrations of IBA (0, 100, 200, 300 and 400 mg L-1), with or without boron (25 mg L-1), along 14 hours without light. The experimental design was randomized in plots, in a factorial arrangement 2x5x2 (two azalea varieties, five IBA concentrations and the presence or absence of boron), with a total of 500 cuttings. Rooting, mean root number, mean root length and mean root dry mass were analyzed. Rooting of both varieties were not influenced by boron, but all treatments showed high percentage for this variable, as the lowest value was 91% at the absence of IBA and boron. The pink variety was superior to the white one what concerns the mean root number, the mean root length and the root dry mass, but the best treatments for it were the ones with low concentrations of IBA with boron. The white variety rooted better without boron. Both varieties, however, showed high rooting power, regardless the treatment used.