New Approaches on Micropropagation of Arracacia xanthorrhiza (“Arracacha”): In Vitro Establishment, Senescence Reduction and Plant Growth Regulators Balance

The present study is part of the efforts to develop a micropropagation protocol for Arracacia xanthorrhiza, focusing on improving in vitro establishment, reducing senescence, and balancing plant growth regulators. To control bacterial contamination during culture initiation, ampicillin and tetracycline were tested using impregnated paper disks. Ampicillin at 100 mg·L−1 achieved 92.4% survival and reduced bacterial contamination to 25.2%, compared to 65.6% in the untreated control, confirming its effectiveness as a low-cost and non-toxic solution. Senescence reduction was evaluated through the addition of activated charcoal and silver nitrate (AgNO3); the latter, at 26 µM, significantly enhanced explant survival, reduced leaf senescence, and promoted shoot and sprout formation. Three plant growth regulators—6-benzylaminopurine (BAP), kinetin (KIN), and meta-topolin (mT)—were tested at multiple concentrations. Meta-topolin at 1 µM produced 3.5 sprouts and 7.2 leaves per plant, demonstrating three times greater biological activity than BAP and optimal morphogenetic response. The integration of antimicrobial control, ethylene inhibition, and cytokinin optimization resulted in a reliable and scalable protocol for A. xanthorrhiza micropropagation. As a concluding remark, these findings provide a practical and efficient framework for clean plant production, with direct applications in conservation, breeding, and commercial propagation of this underutilized Andean crop, while highlighting the need for further validation across genotypes.