Morphogenesis of immature female inflorescences of date palm in vitro

Plant regeneration from immature female inflorescences of date palm (Phoenix dactylifera L.) cultivar Siwi (semi-dry cv.), via somatic embryogenesis was achieved. Immature inflorescences explants were cultured on Murashige and Skoog (MS) medium supplemented with TDZ at 1.0 mg/l. Endogenous hormones (GA_3, IAA, Zeatin and ABA), total soluble sugars (reducing and non-reducing sugars), free amino acids, indoles and phenols were determined. The levels of GA_3 and IAA in explant reached the highest values and then decreased in callus stage. Zeatin, IAA, and ABA levels were higher in embryogenic callus. GA_3 and zeatin in mature somatic embryo maintained a relatively high level while IAA and ABA dropped. The highest significant values of total soluble sugars and their fractions were noted in explant stage. Embryogenic callus stage induced a significant increase in total soluble sugars, free amino acids, phenols and indoles concentrations as compared to callus and mature somatic embryo. Callus induction was achieved by TDZ after 4–5 weeks of culture. The callus differentiated into embryogenic calli on free cytokinin medium. Light microscope observations revealed that the callus consisted of two different types of cells, soft vacuolated cells which did not implicate in embryo formation and compact aggregate cell masses which have the ability to generate the somatic embryos.