The current research was carried out during (2016-2017) season to develop an in vitro propagation protocol for guava explants from mature trees growing in the experimental orchard of Pomology Department, Faculty of Agriculture, Cairo University. The experiment was carried out to investigate the effects of citric and ascorbic acids combination and PVP on media browning during establishment stage. In addition, the effect of nutrient media composition (½MS, WPM and ½DKW) and BAP concentration at 1, 2 or 3 mg L on 1 multiplication rate and shoot growth was examined. The most effective method to control browning problem involved supplementation of culture media with citric and ascorbic acids; this method enhanced shoot induction up to 50.90% with 1.3 shoots per explant. The highest multiplication rate was recorded on ½MS medium; while ½ DKW medium recorded the highest shoot length. BAP at 3 mg L recorded the highest value 1 for number of shoots/explant, shoot length and number of leaves/shoot. Guava micro-shoots were successfully rooted on ½MS medium supplemented with different auxin types. IBA+ NAA recorded the highest rooting percentage as well as the highest root length. Dipping shoot base in IBA solution recorded the highest root number.

Abbreviations: Murashige and Skoog medium (MS) Woody plant medium (WPM) Driver and Kuniyuki walnut medium (DKW) 6-benzylaminopurine (BAP) Indole-3-butyricacid (IBA) Napthaleneacetic acid (NAA) and polyvinylpyrrolidone (PVP)