Acclimatization of coffee ('Coffea racemosa' x 'Coffea arabica') somaclones obtained from temporary immersion bioreactor system (RITA)

Brazil is the first producer and second consumer of coffee in the world. Besides, coffee production also provides a million direct and indirect jobs throughout the supply chain. To increase productivity and reduce cost in conventional tissue cultures the temporary immersion of somatic embryos in bioreactor system was employed. During this process acclimatization is the key problem to obtain high-quality seedlings that required high cost. Therefore, the aim of this study was to evaluate the efficiency of the acclimatization process of coffee somaclones (Coffea racemosa x Coffea arabica) derived from somatic embryogenesis immersed temporarily in bioreactor system (RITA). Embryos derived from leaves of the 'Siriema 05' cultivar coffee (Coffea racemosa x Coffea arabica) were used in this experiment. The acclimatization stage of cotyledon embryos was realized in three experiments: Experiment 1 - Different substrates and size of cotyledon embryos; Experiment 2 - Different substrates and Stimulate concentrations; Experiment 3 - Growth of seedlings in different substrates and Osmocote concentrations. A higher conversion percentage of cotyledonary embryos into seedlings were obtained from embryos grown in the Plantmax medium with vermiculite and Plantmax substrate. Moreover, increasing concentrations of Stimulate and Osmocote to a substrate concentration of 10.9 g L-1 produced better quality seedlings.