Some improved genotypes of cocoa tree (Theobroma cacao L.), have shown in standard study conditions of absence or a very low response to the induction of somatic embryos. This is the case of the recalcitrant genotypes C8 and C15, partially recalcitrant genotypes C14 and C16. This study aims to improve the production of somatic embryos of recalcitrant genotypes. Staminodes and petals excised from the immature buds of the five genotypes C1, C8, C14, C15 and C16 were used as plant material. These floral explants were cultured on different media containing two type of mineral salts such as potassium sulphate (K2SO4) at concentrations 18, 27, 36 and 45 mM and magnesium sulphate (MgSO4) whose concentrations used are 5, 10, 15 and 20 mM. Calli induction was obtained in the five (05) genotypes at percentages ranging from 50 to 100% with staminodes and from 61 to 100% with petals on all media. The transfer of the callogenic explants on the developmental medium allowed the induction of embryogenic calli and somatic embryos after 84 days only with petal explants. The most important PEC and NSE were obtained with two mineral salts concentrations, 27 mM K2SO4 and 15 mM MgSO4 for all genotypes and varied to 20 to 40%. Potassium sulphate (K2SO4) at 27 and magnesium sulphate (MgSO4) at 15 mM are the concentrations of the most suitable mineral salts to overcome recalcitrance of cocoa genotypes.
Key words: Recalcitrant, Theobrama cacao, improved genotypes, mineral salts, somatic embryogenesis.
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