Mini-cutting as a technique to propagate Tabebuia aurea, an important tree found in tropical dry forests

Tabebuia aurea is a hardwood species from Brazil. This species yields high-quality wood for diverse applications and has a high value in phytosociological importance, but little has been done regarding an effective propagation method for large-scale production in nurseries. Alternatively, vegetative propagation techniques such as mini-cutting technology (an evolution of the cuttings technique) can be used, which has the potential to facilitate mini-stumps (stock plants), productive capacity, and vigour of the propagules (mini-cuttings). Therefore, this paper aimed to establish a protocol for vegetative propagation using the mini-cutting technique for Tabebuia aurea. For this, four independent experiments were conducted: the first evaluated the survival and production of mini-stumps between four harvests; the second tested the interaction between mini-cutting types (apical and intermediate) and different concentrations of indole-3-butyric acid (IBA; 0, 2.000, 4.000, and 6.000 mg.L-1) on adventitious rooting; the third analysed the effect of leaf area reduction (0%, 50%, 75%, and 100%) on mini-cuttings; and the fourth verified the substrate effect (100% coconut fibre, 50% coconut fibre + 50% commercial organic compost, and 100% commercial organic compost) on mini-cuttings rooting. The survival; percentage of rooted mini-cuttings; number of roots; length of the largest root; aerial dry mass; and root system dry mass were measured as response variables. The results indicated that all mini-stumps survived four harvests, remained productive, and produced propagules responsive to adventitious rooting. Rooting and mini-cutting survival rates were high, up to 80% without IBA, and the maximum mean setting value of 90% for apical mini-cuttings in the IBA concentration of 2000 mg.L-1 and 4000 mg.L-1 to intermediate mini-cuttings. Treatments without leaf reduction and with a reduction of 50% promoted better results concerning rooting and plant development. The substrate influences adventitious rooting; coconut fibre + organic compost (1:1) are indicated for the species propagation. For the highest system productivity, apical mini-cuttings with 2000 mg.L-1 of IBA, no leaf reduction, and coconut fibre + organic compost (1:1) are recommended as substrates