DONOR PLANT-GROWTH CONDITIONS AND REGENERATION OF FERTILE PLANTS FROM SOMATIC EMBRYOS INDUCED ON IMMATURE ZYGOTIC EMBRYOS OF SUNFLOWER (HELIANTHUS-ANNUUS L)

Immature zygotic embryos of the sunflower inbred line 'Ha 300', cultivated on a modified MS medium containing 6-benzyladenine and a high amount of sucrose, regenerated fertile plants via direct somatic embryogenesis. Plant regeneration from immature sunflower embryos is generally characterized by a relatively high experimental variability resulting from the interactions of multiple factors. We present here a study of some of the factors acting on the donor plants and their influence on the capacity to regenerate plants. Repeated experiments during a 2-year period with greenhouse-grown as well as field-grown plants led to the following conclusions: (i) The use of pesticides, unavoidable in the greenhouse, is compatible with routine regeneration of fertile plants. (ii) The plant growth retardants tested were useful for the production of healthy plants in the greenhouse and had no effect on the regeneration capacity.