MEDIA AND GENOTYPE EFFECTS ON THE DEVELOPMENT AND CONVERSION OF SOMATIC ALFALFA (MEDICAGO-SATIVA L.) EMBRYOS

Various preconditioning treatments of alfalfa (Medicago sativa L.) som atic embryos to improve embryo quality and conversion were studied. Fo ur different regenerating genotypes were compared. Embryogenic culture s were established in liquid culture. Globular embryos were collected and plated on an embryo development medium until they reached cotyledo nary stage. They were then exposed to three treatments: a standard emb ryo development medium (control), media supplementation with 1 mu M ab scisic acid (ABA), 50 mM glutamine and 5% sucrose (T), additional supp lementation with 50 mu M ABA (TT), and additional supplementation foll owed. by desiccation (TTD). Treatments affected embryo conversion, but not uniformly for all genotypes. Embryo conversion was increased (P < 0.05) by pretreatment (T), while only one exhibited any response to a dditional ABA (T vs. TT). Desiccation decreased (P < 0.05) conversion oi pretreated embryos (TT vs. TTD) of all genotypes. The effect of tre atments on plantlet weight was less pronounced and inconsistent across genotypes.