Propagação vegetativa por estaquia utilizando rebrota de cepas de árvores adultas de pau-rosa (Aniba rosaeodora Ducke)

Abstract

The rosewood, Aniba rosaeodora, is a native Amazonian species of economic interest that is threatened with extinction due to intensive extractive exploitation. So, in order to obtain an alternative that reconciles exploration and conservation, we seek to develop the most appropriate cutting technique for the production of seedlings for commercial planting. Therefore, in this study, we investigated the rooting ability of cuttings from adult rosewood shoots using different concentrations of auxin, substrates, and kind of cuttings, as well as described the histological process of adventitious root formation. Three experiments were installed: E1 - test with four concentrations of indolebutyric acid (IBA) via talc (0,0, 1,5, 3,0, 6,0 g kg-1) and three types of substrate (sand, vermiculite, and sand + vermiculite); E2 - test with four types of cuttings (apical, intermediate and basal, obtained from the regrowth branch, and the "regrowth" type, removed from the regrowth itself), in which we verified the soluble carbohydrate and starch contents; And E3 - histological analysis of rooting. For E1 and E2 we evaluated survival (%), rooting (%) and the mean number of adventitious roots, and the length of the longest root per cutting (cm). In E2 we also evaluated the mean number of shoots, length of the largest shoot (cm), and presence of callus (%). Significantly better rooting response was observed with 3.0 g kg-1 IBA compared to the control (0.0 g kg-1 IBA) and with vermiculite substrate compared to the sand. Although there was no interaction between substrate and IBA, the use of auxin showed a tendency to better rooting when using vermiculite or vermiculite + sand as a substrate. Among the types of cuttings, the sprouting was superior for most of the variables, differing from the others in relation to shoot and callus emission. It was also higher in the starch content, which correlated positively with shoot emission. The adventitious root has its origin in the parenchyma formed above the xylem due to the activity of the vascular cambium. The existence of a ring of continuous sclerenchyma after the phloem can act as a mechanical barrier to the emergence of the root.