GENETIC-ANALYSIS OF ORGANOGENESIS IN THE COTYLEDONS OF ZYGOTIC EMBRYOS OF SUNFLOWER (HELIANTHUS-ANNUUS L)

Crosses were made between five cytoplasmic male-sterile and five resto rer sunflower inbred lines. Twenty-five F-1 hybrids and their parents were studied for their organogenesis ability in a randomized block des ign with four replications. Each replication per genotype consisted of ten petri dishes with four explants. Regeneration medium consisted of full MS medium modified by the addition of hormones and solidified wi th 6 g/1 agar. Statistical analysis showed that both general and speci fic combining abilities were significant for all of the organogenesis parameters studied, and both showed several significant positive or ne gative values. General combining ability values were usually higher th an those of specific combining ability, indicating the importance of a dditive genetic control for organogenesis parameters in sunflower. Nar row-sense heritability for the number of explants producing shoots and roots was 65.8%, which suggests that organogenesis of currently infer ior inbred lines in sunflower should be improved in a crossing program .