Induction of somatic embryogenesis in soybean: physicochemical factors influencing the development of somatic embryos

The embryogenic capability of five soybean cultivars (Renascenca, IAS-5, IA C-17, BR-16 and FT-Cometa) was studied at different auxin concentrations (8 , 10 and 12 mg/l naphthalene acetic acid, NAA), at different pHs (5.8 and 7 .0) and at low (8-12 mu Em(-2) s(-1)) and high (27-33 mu Em(-2) s(-1)) ligh t intensities, The experimental design was completely randomized with four replications. Immature cotyledons 4-6 mm in length were placed in the six i nduction mediums evaluated and submitted to two light intensities. Twenty i mmature cotyledons per cultivar were placed on each Petri dish, which was c onsidered to be one replication, The number of somatic embryos per treatmen t per replication was counted. The results showed genotype influence on som atic embryogenic capability of each cultivar, with the most embryogenic cul tivars being BR-16, FT-Cometa and IAS-5. Auxin concentration and pH value a lso influenced somatic embryo production, with 10 mg/l NAA being the best a uxin concentration and 7.0 the best pH value. The interactions cultivar x a uxin, auxin x pH and pH x tight were significant, while other double intera ctions were not. All triple and quadruple interactions were significant, ex cept cultivar x pH x light. No significant differences in somatic embryo pr oduction were observed in medium with different pHs or when the Petri dishe s containing immature cotyledons were exposed to the two light intensities evaluated. However, a higher number of somatic embryos was produced when th e medium pH was adjusted to 7.0.