Coffee synthetic seed production is influenced by somatic embryo development stage and nutritional factors related to the encapsulation matrix

Encapsulated explants are a feasible alternative for artificial seeds with potential applications in agriculture, improving clonal propagation systems as well as short- to medium-term germplasm conservation. The current Coffea arabica propagation method relies mostly on seeds, impairing plantations uniformity that turns on management issues, therefore, synthetic seed technology associated to large-scale somatic embryo production are alternatives to render coffee plant propagation more efficient. This work demonstrates the influence of the somatic embryo development stages and nutritional factors associated to the synthetic coat on the production of artificial seeds for the propagation of C. arabica. Induction of somatic embryos increased by more than 40% in liquid medium MGM compared to solid medium. The use of 2, 4 or 8% (w/v) sodium alginate with 100 mM calcium chloride (CaCl2 center dot 2H(2)O) leads to isodiametric artificial seeds. The use of somatic embryos at less developed stages decreased the germination frequency. The best germination frequency (77.5%) of artificial seeds was achieved with somatic embryos with early-developed radicle and alginate-encapsulated with DEV medium (MS salts with 0.01 mg L-1 of biotin, 100 mg L-1 of myo-inositol and 0.3 mg L-1 of benzyl-amino-purine) as a nutritional matrix. To best of our knowledge, this is the first report on synthetic seed production for C. arabica that, with further improvements, can turn into an easy to handle clonal propagule, for direct sowing on field and short-term conservation, therefore an important step toward the achievement of a better propagation system for this species.