Successful disinfection protocol for orchid seeds and influence of gelling agent on germination and growth

Abstract

Artificial propagation of endangered orchid species is one of the most important actions of conservationists often jeopardized by low numbers of acquired seed, its contamination and viability. Disinfection and chemical composition of media are two of the most important factors contributing to better germination in temperate orchid species. The article deals with three world genera (Epidendrum nocturnum, Prosthechea garciana, Maxillaria rufescens) and one commercial hybrid (Zygopetalum) and describes an effective method of orchid seed disinfection carried out in a centrifuge. Germination percentages of all three genera and one hybrid were between 60 and 90 % from which we concluded that the risk of physical damage to the seeds by centrifugation is not significant. The time needed for disinfected seeds (E. nocturnum, P. garciana, M. rufescens) to swell-form protocorms was 10 days shorter compared to undisinfected seeds (Zygopetalum hybrid - green capsule method) and some other studies. Adequate wetting and stratification of the seed is very important for successful germination, which resembles processes in natural environment. Additionally, this method solves the problems of collecting and transferring the seeds after disinfection. It is also important that the time needed for disinfection is shorter, which is desirable for some sensitive species. Our study also focuses on importance of gelling agent, namely Gellan gum and agar, since we noticed an obvious superiority of the former in all phases of in vitro development.