IMPROVED TECHNIQUES FOR INVITRO-PROPAGATION AND GERMPLASM STORAGE OF PAPAYA

A multiplication technique based on subculture of nodal sections from apically dominant shoots is described for papaya (Carica papaya L.). Best multiplication rates were obtained when single-node papaya sections were cultured on a modified De Fossard medium containing 0.5 mum of both BAP and NAA. Shoots that developed from axillary buds were dissected and cultured for 3 days on rooting medium containing 10 mum IBA and subsequently transferred to hormone-free Drew-Smith (DS) medium. Explant growth rate was significantly reduced by substitution of 1% fructose for 2% sucrose in the medium. However, after 12 months of incubation at 25C without subculture, 100% of shoots on medium containing fructose were recovered when nodal sections were subcultured and grown using the above techniques. Consequent advantages are proposed for germplasm storage in lieu of low-temperature incubation. These techniques may have application to other species. Chemical names used: N6-benzylaminopurine (BAP), 1H-naphthaleneacetic acid (NAA), IH-indole-3-butyric acid (IBA).