Aseptic establishment and in vitro germination of Theobroma cacao L.: Redox strategies to overcome recalcitrance

In vitro cultivation of Theobroma cacao L. poses critical challenges, primarily due to the recalcitrant nature of its seeds and the high susceptibility of its tissues to phenolic oxidation. This research evaluated the effect of bioactive modulating agents (cysteine, ascorbic acid, and activated charcoal) and genotypic factors on in vitro germination. By employing an optimized surface disinfection methodology, 100 % asepsis was achieved, significantly surpassing historical records of contamination-related losses (up to 63 %). Germination efficiency reached 86.25 %, being significantly influenced by the Genotype × Environment interaction, where the 'Ocumare 61' cultivar demonstrated superior morphogenic competence. Statistical analysis validated robust mathematical models (R ² _adj of 73.77 % for germination and 81.05 % for oxidation), confirming that supplementation with activated charcoal effectively neutralized the cytotoxic quinone cascade through physical adsorption—a primary limiting factor in the 'Ocumare 60' cultivar. Response surface analysis identified the optimal performance in the M3 treatment with 'Ocumare 61'. We conclude that asepsis control and the stability of the redox microenvironment are decisive conditions for unlocking the germinative potential of cacao seeds. These findings establish a predictive framework that strengthens protocols for mass micropropagation and the conservation of elite germplasm.