In vitro root formation in Anacardium occidentale microshoots

Abstract

Cultural conditions affecting the induction of rhizogenesis in vitro were evaluated in cashew (Anacardium occidentale L.) shoot-node-derived microshoots. The application of auxins was essential for the formation of adventitious roots. A 5-d indole-3-butyric acid (IBA) induction period was more suitable than continuous IBA treatment or a shorter induction period. N6-[2-Isopentenyl]adenine in low concentrations (0.3 - 1 μM) in the root induction medium supported root formation. Precultivation of microshoots with gibberellic acid (GA3) suppressed the subsequent rhizogenesis. Activated charcoal did not affect rooting. No significant differences in rooting abilities of cashew shoots were observed between 25, 29 and 35 °C and roots did not develop at 19 °C. Salts of low osmotic composition were more suitable than richer media. Microshoots originated from cotyledonary nodes showed higher rooting when compared to standard microshoots.