The effect of the concentration and proportion of growth regulators in an initial medium on Narcissus L. ‘Carlton’ morphogenesis in cultures of Pc stage flower bud explants was investigated. Ovary and flower stem explants were cultured on solid Murashige and Skoog (MS) media with cytokinin – 6-Benzyladenine (BA) or Zeatin (ZEA) (0.5–50 µM) – in combination with auxin – 4-Amino-3,5,6-trichloropicolinic acid (Picloram), 2,4-Dichlorophenoxyacetic acid (2,4-D) or α-Naphthaleneacetic acid (NAA) (1–50 μM). The ratios of cytokinin and auxin in the initial medium determined the morphogenetic pathways and the level of cytokinin proved to be a critical factor. Somatic embryogenesis was achieved for a cytokinin and auxin ratio of 1:1–10, bulb organogenesis – for a 1:0.4–1 ratio and rhizogenesis – for a 1:20–100 ratio. The minimum concentration of cytokinin in the initial medium for somatic embryo and bulb formation was 5 μM. A lower level of cytokinin (0.5 μM) resulted in rhizogenesis. Considering the effect of auxin, Picloram stimulated the initiation of somatic embryos and the 2,4-D enhanced embryo maturation and conversion.

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