BIOESTIMULANTE E ÁCIDO GIBERÉLICO COMO NOVA PROPOSTA NO ENRAIZAMENTO DE MINIESTACAS DE Ilex paraguariensis A. St.-Hill.

Abstract

The production of yerba mate seedlings by the seminiferous route has several limitations and an alternative to the propagation of this species is the vegetative propagation, highlighting the minicutting technique. For the species there are no reports on the use of gibberellic acid in minicuttings. Biostimulants have been pointed out as potential alternative uses that can enable the rooting of species that are difficult to propagate, with few studies involving tree species and also non-existent in mini-cuttings of yerba mate. Thus, the present research aimed to evaluate the effect of the application of biostimulant and gibberellic acid (GA3) in the cultivation of mini-cuttings of yerba mate. The research was developed at the company Golden Tree Reflorestadora LTDA. As plant material, three clones identified as: BRS 408, BRS 409 and BRS BLD Aupaba were used. The minicuttings were treated with four concentrations of the biostimulant (0; 25; 50 and 100 mgL-1), totaling 12 treatments, with four replications. In a second experiment, four concentrations (0, 50, 100, 150 mgL-1 ) of gibberellic acid were evaluated, totaling 12 treatments, with four replications. At 150 days of age, mortality, rooting percentage, callogenesis, as well as parameters related to growth, seedling quality and gas exchange were evaluated. Under the effect of the biostimulant, the highest percentage of mortality was obtained at the concentration of 100 mg L-1 and the lowest without the use of the product. As for rooting, the highest percentage found was in the Witness treatment (not using the product). For callogenesis, the highest percentage obtained was under the effect of the concentration 25 mg L-1 . The biostimulant showed a significant effect only for the neck diameter and for the gas exchange variables, only for the internal concentration of CO2 (Ci). The tested concentrations of biostimulant had no effect on the rooting of the mini-cuttings of yerba mate and the clones did not differ in terms of rooting. Under the effect of gibberellic acid, for mortality there was no significant difference between treatments. For rooting, the Aupaba clone under the effect of concentrations of 50 mg L-1and 100 mg L-1 was superior to the other treatments. As for callogenesis, the concentration 150 mg L-1 had the highest median and did not differ statistically from the Control and the concentration 50 mg L-1 . Gibberellic acid was significantly expressive in height, root dry mass and Dickson quality index. Under the effect of gibberellic acid, stomatal conductance (gs), internal CO2 concentration (Ci) and transpiration rate (E) showed better results. The most suitable concentrations of gibberellic acid tested in rooting for clone Aupaba were 50 mg L-1 and 100 mg L-1. The clone that showed better rooting under the effect of gibberellic acid was Aupaba.