ABSTRACT
The usual propagation method for Dalbergia nigra is via seedings; however, the seasonal supply has a variable quantity of seeds which limits the continuous production of seedlings. Therefore, the objective of this study was to establish a vegetative propagation protocol via mini-cuttings technique for D. nigra from juvenile shoots obtained from seedlings. The experimental design was completely randomized in a 2 x 2 x 4 factorial scheme, with two geographical origins: two controlled release fertilizer doses (4.0 and 8.0 g.dm-³) and four indole-3-butyric acid (IBA) concentrations (0; 2,000; 4,000; and 6,000 mg.Kg-1), with four replications. The mini-cuttings were removed from the tubes after 60 days of propagation in the greenhouse, and the substrate was completely removed by washing in running water to observe the roots. The survival percentage, rooting, rooting speed and variables related to mini-cuttings vigor (largest root length (RL, cm.plant-1), number of roots (NR), surface area (SA, mm2), root volume (RV, mm³) and root dry mass (RDM, g.plant-1) were measured. The results indicated that D. nigra has an aptitude for vegetative propagation by mini-cuttings with survival values and rooting greater than 70%. Geographical origins present a different set of responses for survival, rooting and vigor of mini-cuttings. Stock plant nutrition influences mini-cuttings root growth. IBA concentrations did not promote an effect on the mini-cuttings rooting percentage; however, exogenous auxin at the dose of 6,000 mg.Kg-1 provided mini-cuttings with greater vigor in their radical system. Nonetheless, further research is suggested to define the feasibility of using this regulator in the vegetative propagation of this species.
Keywords:
Conservation; Clonal forestry; Adventitious rooting; Forest nutrition; Geographical origin
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