ANALYSIS OF COTYLEDON CULTURE TO MEASURE GENETIC-VARIABILITY FOR ORGANOGENESIS PARAMETERS IN SUNFLOWER (HELIANTHUS-ANNUUS L)

Crosses were made between three cytoplasmic male sterile and six resto rer sunflower inbred lines. Fl hybrids and their parents were studied for their organogenesis ability in a randomized blocks design with thr ee replications. Seeds were surface sterilized, and subsequently germi nated on hormone free half strength MS medium. Regeneration medium con sisted of full strength MS medium modified by adding hormones and soli dified with 0.5% phytagar. Cotyledons from 2 days-old seedlings were s plit in half, and the four explants of each seed were transferred to r egeneration medium. A replicate for each genotype consisted of ten Pet ri dishes containing four explants, Statistical analysis showed a high genetic variability for organogenesis parameters. Both general and sp ecific combining abilities were significant for all of the organogenes is parameters studied, with either positive or negative values. Genera l combining ability values were usually more important than those of s pecific combining ability, indicating the importance of additive genet ic controls for organogenesis parameters in the sunflower. Copyright ( C) 1996 Elsevier Science Ireland Ltd