Multiplication of juvenile black wattle by microcuttings

The influence of mineral formulation, growth regulators and activated charcoal on micropropagation of juvenile black wattle (Acacia mearnsii) was studied. Nodal segments of one-month-old seedlings were used as starting material. After 30 to 45 days, they developed into shoots, which were divided into microcuttings and transferred to fresh media. The addition of 2 g l(-1) of activated charcoal to basal medium (3/4 strength MS salts and MS vitamins) improved the multiplication phase, reducing leaf chlorosis and raising the percentage of elongated shoots. The multiplication rate varied between 1.7 and 3 every month. Rooting percentage too was higher in the presence of charcoal, even when auxin was not added to the culture medium. The addition of 8.87 muM of benzyladenine and/or 1.44 or 2.88 muM of gibberellic acid did not influence significantly the multiplication, nor modifications in the FeSO4, MnSO4, CaCl2 content of the medium. The system described allows the multiplication, elongation and rooting of black wattle in one step