Résumé
The incorporation of new technologies such as in vitro selection and protoplast fusion methods into citrus improvement programs offers new opportunities to facilitate, expedite, and fully utilize germplasm variability for both scion and rootstock. Somatic embryogenesis plays a central role in these methods. In citrus, the main factors influencing callus induction and somatic embryogenesis are genotype, composition of culture medium and kind and stage of explants. The aim of the study was to develop protocols adapted for embryogenic callus induction of different citrus rootstocks. Embryos of mature seeds, style from flower buds collected during full bloom, and ovule preleved 8 week after anthesis were used as explants. All explant material cames from the citrus germplasm collection of INRA EL Menzeh. The basic nutrient medium of Murashige and Skoog (1962) or MS medium was used. Three medium were compared Ml = MS. M2 = MS + kinetin 1mg/l and M3 = MS + 2-4 D 1 mg/l + BAP 0.5 mg/l. Cultures were incubated at a temperature of 26- 28°C under 70% relative humidity, in the dark. After culturing of embryo, ovule or style of 37 citrus rootstocks, calli were induced. The percent of friable callus induction varied between explants, culture medium and rootstock genotypes. Detailed results are given and best combinations of explants and culture medium are discussed for the different genotypes. (Texte intégral)