Callus Induction and Direct Shoot Formation in in Vitro Cultured Immature Inflorescence Tissues of Coconut

Clonal propagation of elite palms is a promising possibility for producinguniform planting material and improving productivity in coconut lands.In the absence of a natural vegetative propagation method, in vitro cultureremains the only approach for vegetative multiplication of coconut.Immature inflorescence material has shown to be a promising sourceof explants for coconut tissue culture. In the present study, four differentculture media (medium 72; modified Eeuwens Y 3 medium; coconut antherculture medim; modified Blake's medium) were evaluated for callus inductionin floral explants: Immature inflorescences were collected non-destructivelyfrom 12 year old Sri Lanka-tall coconut palms and rachilla segmentsobtained from these inflorescences were cultured on above media.Out of the four culture media tested, callus production was observedonly in the explants cultured on medium 72. In this medium (which contained24 uM 2,4-dichlorophenoxyacetic acid and 0.25% activated charcoal),about 30% of the floral explants produced compact, highly embryogeniecalli. Direct regeneration of shoots from floral primordia occurred at &very low frequency in the modified Eeuwens Y 3 medium which contained200 pM 2,4-dichlorophenoxyacetic acid and 0.2% activated charcoal. Nocallogenesis or direct organogenesis were observed in the floral explantscultured on the other two culture media tested.