Comportamento de duas espécies florestais arbóreas cultivadas in vitro e in vivo em função do cobre

Abstract

Contamination of soils by copper can alter physiological development and establishment of plants. The use of copper tolerant and extractive forest species for revegetation of contaminated soils has been shown to be an alternative of recovery by the phytoremediation method.In this sense, forest species, due to their higher production of biomass, are capable of immobilizing and exporting outside of any system, greater amounts of toxic elements present in the soil.In the present work, the objective was to study the behavior of two tree species in vitro and in vivo cultivated under conditions of excess copper.Studies were carried out with the Peltophorum dubium and Handroanthus chrysotrichus, one of them conducted in a growing room in a tissue culture laboratory, and the second in a greenhouse under controlled conditions.In study 1 it was possible to obtain high general averages of in vitro survival and establishment in the concentrations of copper tested.The species showed tolerance up to the 16 mg L-1 concentration, with the 8 mg L-1 dose giving the best performance for the species; the toxic dose was 64 mg L-1.For Peltophorum dubium, at all doses survival was adequate up to 60 days, but at 90 days a high mortality of the explants at 64 mg L-1 was observed.Handroanthus chrysotrichus showed low survival at 64 mg L-1 already at 30 days, indicating that is a less tolerant copper species.Low number of leaves and root formation were also observed in treatments with low survival.In study 2, as a function of the copper concentrations, Handroanthus chrysotrichuspresented reduction only in the diameter of the stem, whereas in Peltophorum dubium, it was at height.In general, in the in vitro culture studies, the species demonstrated that they benefit from the increase in the concentration of copper up to 8 or 16 mg L-1, differently depending on the period of cultivation.Likewise, the in vitro cultures of both species demonstrate copper tolerance, but were impaired by the increase to 64 mgL-1 of CuSO4, which is excessive.In greenhouse cultivation studies, only the growth variables of the stem diameter in Handroanthus chrysotrichusand plant height in Peltophorum dubiumare significantly affected by the addition of copper to the native contents of the metal in the soil.The results obtained have the potential to contribute simultaneously to the optimization of micropropagation protocols and to the development of efficient phytoremediation and phytoextraction methodologies of degraded areas inserted in the Mata Atlântica and Pampa biomes, reducing the environmental impacts of copper contamination.