Paclobutrazol as an alternative to improve propagation of Rubus brasiliensis Mart.

Abstract

Because this species Rubus brasiliensis Mart. is not commercially cultivated as an agricultural crop, there is significant lack of information on cultivation practices, particularly about propagation. The present study was carried out to evaluate rooting of stem cuttings harvested at different dates and subsequently treated with indole-3-butyric acid (IBA) concentrations. We also evaluated rooting of root cuttings of different diameters treated with different concentrations of naphthalene acetic acid (NAA). Based on results obtained, an additional trial was established using paclobutrazol (PBZ) associated to IBA to improve rooting. Studying the influence of five concentrations of IBA (0, 1000, 2000, 3000 and 4000 mg L − 1) and five collection dates (September 11th and November 14th, February 20th, April 20th and June 18th, in Brazil) in a factorial design, we concluded that the use of IBA increased the rooting of stem softwood cuttings of R. brasiliensis, with variation according to the date of collection, but with low rooting percentages, less than 16%. For root cuttings, the use of NAA (0, 2500 and 5000 mg L − 1) and various diameters of cuttings (2.5 mm, 5.0 mm, 7.5 mm, 10 mm and 12.5 mm) did not return positive results, showing the technique was not efficient. The use of PBZ (0, 100, 200 and 400 mg L − 1) associated with IBA (0, 1, 2 and 4 g.L − 1) proved to be important for rooting of cuttings with significant differences compared to the control. The use of IBA alone at 1 g.L − 1 resulted in rooting no higher than 16.67%. When PBZ was used alone at 200 mg.L − 1, 20% rooting was obtained. However, when PBZ (400 mg L − 1) was combined with IBA (1 g.L − 1), rooting of cuttings improved to 36%, showing a potential synergistic effect. Ours results showed that the combination of an auxin with PBZ can promote rooting in greenberry stem cuttings. In addition, PBZ is readily available to growers, being of easy solubility and with low toxicity.