Effects of plant growth regulators on in vitro shoot regeneration and rooting of an F1 hybrid between Cymbidium aloifolium and Cymbidium finlaysonianum

Abstract

This study evaluates the effects of plant growth regulators on in vitro shoot regeneration and root formation of the F1 hybrid (♀ Cymbidium aloifolium × ♂ Cymbidium finlaysonianum). The experiment determined the optimal culture medium (MS, 1/2 MS, KC, VW) and the influence of cytokinin (BAP, Kinetin, TDZ), auxin (IBA, NAA, IAA), and activated charcoal (0-4 g/l) on seed germination, shoot multiplication, and root formation stages. Results showed that MS medium was the most suitable for germination, achieving a 90.37% germination rate and the shortest protocorm formation time (7-8 weeks). The highest shoot multiplication efficiency was observed with 2.0 mg/l BAP, yielding an average of 4.30 shoots/explant, a shoot length of 7.73 cm, and a fresh weight of 323.05 mg. For root formation, the combination of 2.0 mg/l NAA and 2.0 g/l activated charcoal produced the best results, with an average of 5.20 roots/explant, a root length of 6.35 cm, and a fresh weight of 355.05 mg. This study provides a scientific basis for optimising the in vitro propagation protocol for the F1 hybrid, contributing to the generation of a diverse initial hybrid population, serving as a foundation for the selection and development of promising Cymbidium hybrid lines.