Agronomic performance of Coffea canephora P. trees derived from large-scale somatic embryo production in liquid medium

In order to validate the propagation technology of Coffea canephoraPierre var. Robusta via somatic embryogenesis in liquid medium, the clonal fidelity of regenerated trees has been assessed for the first time in large-scale field trials. A total of 5067 trees originating from 5- to 7-month-old embryogenic cell suspension cultures were planted in the Philippines and in Thailand for comparing with control trees derived fromin vitro axillary budding (microcuttings). For the observed morphological traits and the yield characteristics, no significant differences were seen between the somatic seedlings (SS) and the microcutting-derived trees (MC).After three harvests in Thailand, the most productive clones had a cumulative yield higher than 3000 kg of green coffee ha-1. The only detected ‘off-type’ concerns a low vigorous phenotype (2.3% in the Philippines and 3.8% in Thailand), which is probably the consequence of the planting out process as it is also observed in the control trees. The occurrence of some phenotypic variants difficult to visualize or somaclonal variations at the DNA level cannot be excluded. Nevertheless, this study shows that this propagation method can be used for large-scale commercial applications without any negative unforeseen consequences for the grower.