In vitro root formation in Anacardium occidentale microshoots

Cultural conditions affecting the induction of rhizogenesis in vitro were e valuated in cashew (Anacardium occidentale L.) shoot-node-derived microshoo ts. The application of auxins was essential for the formation of adventitio us roots. A 5-d indole-3-butyric acid (IBA) induction period was more suita ble than continuous IBA treatment or a shorter induction period. N-6-[2-Iso pentenyl]adenine in low concentrations (0.3 - 1 muM) in the root induction medium supported root formation. Precultivation of microshoots with gibbere llic acid (GA(3)) suppressed the subsequent rhizogenesis. Activated charcoa l did not affect rooting. No significant differences in rooting abilities o f cashew shoots were observed between 25, 29 and 35 degreesC and roots did not develop at 19 degreesC. Salts of low osmotic composition were more suit able than richer media. Microshoots originated from cotyledonary nodes show ed higher rooting when compared to standard microshoots.