LEAFLET DEVELOPMENT, INDUCTION TIME, AND MEDIUM INFLUENCE SOMATIC EMBRYOGENESIS IN PEANUT (ARACHIS-HYPOGAEA L.)

Factors affecting somatic embryogenesis in peanut (Arachis hypogaea L. ) using leaflet explants of seedlings obtained from aseptically germin ated embryo axes were evaluated. Somatic embryogenesis was influenced by developmental stage, leaflet size, induction medium, and time on in duction medium. Leaflets that were 5-7 mm long had a greater embryogen ic response than smaller or larger leaflets. Percent embryogenesis and mean number of embryos were related to the developmental stage of ger minating seedlings. A greater response was obtained if leaflets were f olded and closely appressed. Preselection of leaflets increased percen t embryogenesis from 21% up to 67%. As leaflets unfolded, embryogenesi s decreased; open leaflets lost the potential for embryogenesis. The o ptimal induction conditions were a 7-day incubation period on Murashig e and Skoog medium with 136 mu M 2,4-dichlorophenoxyacetic acid and 0. 93 mu M kinetin. Somatic embryos germinated to form plants that exhibi ted a normal morphology.