Effect of Indole-3-butyric acid (IBA) and 3-Indoleacetic acid (IAA) on promoting roots on micropropagated Dyckia distachya Hassl

Different studies have focused on several aspects of the developmental biology of Dyckia distachya Hassl., a terrestrial endemic and endangered bromeliad native to Brazil. This species, which is at risk of extinction due to the endangerment of its habitat, the Atlantic Forest, has functional roots that absorb nutrients from the soil. This study aimed to evaluate the efficiency of two auxins, Indole-3-butyric acid (IBA) and Indole-3-acetic acid (IAA), to promote roots in micropropagated D. distachya shoots, both in vitro and ex vitro, to improve survival during acclimatization. Shoots were exposed to varying concentrations (0–50 μM L⁻¹) and time exposure durations (0–20 days) of IBA and IAA in a completely randomized design, with statistical significance assessed through ANOVA and SNK tests (p ≤ 0.05). Enhanced in vitro rooting rate (80 %) and root length were achieved in response to 12.5 μM L⁻¹ IAA over 15 days, whereas IBA required longer exposure (20 days) to yield maximal root length. Ex vitro root induction showed the highest rate of root formation (87.6 %) and root length in response to 100 μM L⁻¹ IAA. In vitro rooting produced robust and numerous roots, contributing to higher plantlet survival during acclimatization (up to 99.6 %). These findings demonstrate the efficacy of IAA, particularly in vitro, in promoting root development and survival of D. distachya plantlets. The study provides a reliable rooting protocol that enhances micropropagation success, supporting the efforts to propagate and conserve this critically endangered bromeliad.