In Vitro Root Formation in Anacardium Occidentale Microshoots

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.