Propagation of macadamia (Macadamia integrifolia Maiden & Betche) by cuttings

Macadamia trees require a long period for flowering when propagated by seeds. To anticipate the yield, maintain cultivar characteristics, and increase the homogeneity of nut quality, it is essential to establish orchards with grafted trees. Although semi-hardwood cutting propagation tests have been performed in Brazil, no method has been shown to be appropriate at a large scale due to the difficulties in implementation of techniques or the high cost. Establishing an effective and affordable protocol may provide great improvement to this productive chain since it will meet the demand of nurseries and stimulate the expansion of orchards. The aim of this study was to develop a protocol for macadamia semi-hardwood cutting propagation. Six cultivars (HAES 344, HAES 816, HAES 660, IAC 4-12B, IAC 9-20, and IAC 4-20) were evaluated and selected because of their ample cultivation in Brazil. The propagation material was collected for four months (October and November 2018, and February and March 2019). The semi-hardwood cuttings were also soaked in indole butyric acid (IBA) at three different concentrations (0, 5, or 10 g L-1) and in the commercial product Clonex®. The experiment was arranged in a two-way completely randomized design with four replicates and data were analyzed by R software. The cultivar IAC 4-12B showed the highest index for root development (37.0%). The treatments did not show significant differences between IBA doses and Clonex® for root development (IBA 10 g L-1 - 31.5%, Clonex® - 29.4%, and IBA 5 g L-1 - 27.4%). November was the best cutting season for root development of semi-hardwood cuttings (10.0%).