Chitosan mediated organogenesis in hybrid Dendrobium (Dendrobium Enopi x Dendrobium Pink Lady) through protocorm-like bodies

Orchids are regarded as some of the most attractive ornamental plants owing to their diverse floral morphology and striking colours. The regeneration of orchid plantlets via micropropagation serves as a cutting edge approach for the production of orchid plants in large scale. This study focuses on the effects of chitosan as an elicitor in promoting growth and development of a recalcitrant orchid hybrid (Dendrobium Enopi x Dendrobium Pink Lady). Exogenously applied phytohormones, including 1-naphthaleneacetic acid (NAA), 6-benzylaminopurine (BAP), kinetin, indole‐3‐butyric acid (IBA) and 2,4-dichlorophenoxyacetic acid (2,4-D), displayed no apparent effect in inducing proliferation and organogenesis capacity of in vitro protocorm-like bodies (PLBs) cultures. Optimal fresh weight of PLBs, and qualitatively healthy PLBs were obtained in media supplemented with 0.5 mg/L chitosan and 1.0 mg/L NAA. Chitosan is a useful elicitor with highest PLB fresh weight (0.952 g) in media with 0.5 mg/L of chitosan. Chitosan prevailed over other PGRs with regards to organogenesis induction capacity. At a concentration of 0.25 mg/L, chitosan induced the highest shoot formation rate, with 15.69 and 25.29 shoots per explant being induced at the 60th and 100th day, respectively, and the highest rooting capacity at 83.33%, with 5.15 roots per explant, recorded after 180 days.