In vitro propagation of Costa Rican guava (Psidium friedrichsthalianum (O. Berg) Nied.) plantlets from seedlings in the temporary immersion system RITA®, rooting and acclimatization

Fruits of Costa Rican guava (Psidium friedrichsthalianum (O. Berg) Nied) contain phenolic compounds and offer the possibility of creating novel functional foods with benefits for human health. In vitro culture, a propagation technique currently scarce for this species, can be developed for the propagation of genotypes with desirable fruit and agronomic traits. Woody Plant Medium supplemented with the growth regulators 6-benzylaminopurine, kinetin and gibberellic acid at concentrations of 0.5, 1.0 and 1.5 mg/L was used. Microcutting resulted in a more favorable response to BAP for variables such as the number of shoots (NS), number of nodes (NN) and number of leaves (NL). The mean NS was 4.80 when 1.5 mg/L BAP was used, whereas the optimal response for NN (14.73), NL (30.73), and shoot length (SL) (2.2 cm) was 0.5 mg/L BAP. WPM was subsequently supplemented with 0.5 mg/L BAP for multiplication in RITA®. The number of shoots (6.33 ± 2.31) and multiplication coefficient (5.33 ± 2.31) were greater than those of the semisolid media, with values of 4.30 ± 1.32 and 3.30 ± 1.32, respectively. For the rooting phase, the greatest response to the number of roots (3.75 ± 2.79), root length (2.46 ± 1.61 cm) and plant height (7.00 ± 0.63 cm) was associated with 0.3 mg/L indol-3-butyric acid. The survival rate of the rooted plantlets in the greenhouse was greater than 90% when the plants were exposed to IBA. This work provides new knowledge to the scarce literature on in vitro culture of P. friedrichsthalianum, particularly on the use of RITA®, which is described for the first time. New contributions to rooting and acclimatization for this species are comprehensively detailed.