Micropropagation of arracacha: from meristem isolation to plant acclimatization

Arracacha is vegetatively propagated; thus, in vitro tissue culture combined with rooting and acclimatization is an alternative for acquiring high-quality disease-free plantlets. For in vitro propagation studies, three experiments were conducted. The first evaluated different combinations of plant growth regulators (PGRs): B5 medium formulation without a PGR, B5 + 0.2 mg·L ⁻¹ 6-benzylaminopurine + 0.01 mg·L ⁻¹ 1-naphthaleneacetic acid, and B5 + 0.3 mg·L ⁻¹ 6-benzylaminopurine + 0.1 mg·L ⁻¹ 1-naphthaleneacetic acid; this assay used three arracacha cultivars ('BRS Rubia 41', 'BRS Acarijó 56', and 'Amarela de Senador Amaral'). The second experiment evaluated the effect of photoperiod (10, 12, and 14 h) on three cultivars ('Amarela de Senador Amaral,' 'BRS Catarina 64', and 'BRS Rubia 41'). The third tested different concentrations of indolebutyric acid (IBA) (0.0, 3.0, 6.0, 9.0, 12.0 mg·L ⁻¹) with and without activated charcoal (1.0 g·L ⁻¹), and different formulations (B5 and ½ B5) supplemented with 0.3 mg·L ⁻¹ 6-benzylaminopurine and 0.1 mg·L ⁻¹ indolebutyric acid sealed with one of three different materials (parafilm, gauze, polyvinyl chloride). The culture medium with the highest shoot regeneration rate that was most favorable for in vitro establishment was B5 + 0.3 mg·L ⁻¹ 6-benzylaminopurine + 0.1 mg·L ⁻¹ 1-naphthaleneacetic acid. Photoperiod did not affect cultivar development, and the responses varied among cultivars. Activated charcoal did not improve the rooting rates. The culture medium with ½ B5 sealed with PVC promoted better in vitro rooting and hardening of arracacha.