Estabelecimento in vitro de Swietenia macrophylla King em cultura de tecidos vegetais

Abstract

Mahogany (Swietenia macrophylla King) is an arboreal species native to the Amazonian environment, which has been under intense extractive pressure due to the properties of its wood, being classified as vulnerable. Micropropagation is the technique of plant tissue culture that offers a way to propagate large-scale plant individuals to replenish them in the environment or preserve them in vitro. The in vitro establishment, which is the first step in the micropropagation process, of the explants from these individuals has as a barrier the endogenous contamination by pathogenic microorganisms and the phenolic oxidation of explants of arboreal species, both of which can cause the loss of the explants. Microorganisms live both superficially and endophiatically on plants in the field, and may have benefits or harm to them. The phenolic oxidation occurs among other forms, when the explant is excised from the matrix plant whose phenolic compounds exist in it react with the atmospheric oxygen generating the darkening and, finally, the explant necrosis. Thus, this experiment aimed to test the best treatment to reduce both endogenous contamination and phenolic oxidation in spindle segments of the mahogany leaf through the combination of antimicrobial and antioxidant substances. At the twenty days of establishment of the in vitro explants the contaminants were reduced from 60% in the control treatment to 20% in treatment 3 with a mean of 42.5% for contamination 57.5 for healthy explants, while the phenolic oxidation had a mean of 95% for oxidations and 5% for non-oxidation in the explants. It was concluded that the treatments were effective to resolve the contaminations while the treatments to resolve the oxidations and necroses of the explants were not effective, and in other experiments the solution of polyvinylpyrrolidone or other antioxidant to bathe the explants shortly after disinfestation or at the time of isolation of the explants or further test other antioxidants combined with pre-treatments to decrease phenolic oxidations.