ASPARAGUS (Asparagus officinalis L.) RHIZOME ORGANOGENESIS BY COMBINING AUXINS AND

Abstract

In vitro propagation is an option for increasing viable asparagus (Asparagus officinalis L.) propagules. One of the main factors that have an influence in the success of in vitro protocols is the concentration of growth regulators in the culture medium; of these regulators, auxins and cytokinins are the most used. The hypothesis of the study was that the generation and biomass of shoots from the explant increase with the optimal balance of auxins and cytokinins. The objective was to evaluate the effect of auxins and cytokinins on asparagus development in vitro. The experiment was established with a completely randomized design and a 2 × 3 × 2 × 4 factorial arrangement (type of cytokinin, concentration of cytokinin, type of auxin, concentration of auxin) and 48 treatments with three replications each. Rhizomes were cultivated in media to which cytokinins, 6 benzyl aminopurine (BAP) and kinetin (KIN) and the auxins, indole butyric acid (IBA) and acetic naphthalene acid (ANA) were added at three concentrations of cytokinins (0.0, 0.5 and 1.0 mg L-1 ) and four of auxins (0.0, 0.1, 0.5 and 1.0 mg L-1 ). After 21 d of incubation, the highest production of turions (43.3±1.1 shoots) was obtained with 1 mg L-1 BAP + 0.1 mg L-1 IBA. With 0.5 mg L-1 BAP + 0.5 mg L-1 ANA after eight weeks of in vitro culture, the largest increase of fresh biomass was 7.12±0.8 g. Rooting reached 66.6 % and the multiplication rate was 3.3 rhizomes per explant. BAP was important for vegetative buds and KIN induced turion elongation. IBA and ANA were essential for the formation of the root system. The balance of cytokinin and auxin concentrations is necessary for asparagus organogenesis.