In vitro elongation of Eucalyptus dunnii shoots for different genotypes and concentrations of naphathalene acetic acid (NAA)

Abstract

The objective of this study was to evaluate the effect of different concentrations of naphthalene acetic acid (NAA) associated with the fixed concentration of 6-benzylaminopurine (BAP) on in vitro elongation of shoots derived from previously multiplied genotypes of Eucalyptus dunnii. Shoots were prepared and inoculated under aseptic conditions in nutrient broth 1/2MS. The experiment was conducted in a completely randomized design in a factorial scheme 5 x 6, in which the levels of the factor "A" referred to the different genotypes (labeled 2, 3, 4, 6, 7 and 10) and levels of factor "B", the NAA concentrations (0, 0.25, 0.5, 0.75 and 1 mg L^-1). The experiment was performed with five repetitions of a bottle containing three explants. Thirty days after inoculation of the explants was rated the number of elongated shoots, average length (mm) of shoots and formation of hyperhydricity (%). The genotypes showed different behavior in elongation phase, demonstrating the possibility of selection in vitro. The addition of 0.5 mg L^-1 NAA increased the number of elongated shoots and increased the length of the shoots. Concentrations higher than 0.5 mg L^-1 NAA exhibit increased formation of hyperhydric structures, damaging the shoots elongation. The proper balance of auxin/cytokinin and the selection of suitable genotypes is critical to the success of shoots in vitro elongation of E. dunnii.