Ecology, Environment and Conservation Paper

SYMBIOTIC GERMINATION IN ORCHIDS: AN OVERVIEW OF EX SITU AND IN SITU SYMBIOTIC SEED GERMINATION

Tadar Jamja, Sunil Bora, Ruthy Tabing, Nangki Tagi, Arvind Kumar Chaurasiya, Sushma Ningombam Devi and Mero Yangfo

Abstract

Plant family Orchidaceae is well-known in the global floriculture market for its beauty, long-lasting flowers, and exquisite variation in flower colour, shape, size, foliage form, and texture. They are thought to be one of the most varied and evolved vascular flowering plants. Orchids produce millions of dust-like seeds in a pod, but they have a unique and persistent problem with seed propagation due to a lack of food reserve ‘endosperm’ in their minuscule seeds, which often fail to germinate in a natural environment without being in symbiotic association with compatible mycorrhizal fungi. Symbiotic seed germination takes advantage of the fungal-orchid symbiosis interaction, in which orchid seeds are germinated in different growth media after being inoculated with orchid mycorrhizal fungi. It has been one of the most important and commonly used propagation techniques for orchid conservation and reintroduction programmes around the world. Prior to the introduction of the in situ technique in the early 1990s, symbiotic seed germination was performed using an ex situ procedure. The in situ technique was designed to improve the efficiency of orchid seed propagation and reduce acclimatisation challenges during the reintroduction programme. It emphasises germination in natural environmental settings, with the idea that the presence of suitable fungi in the surrounding environment can influence germination. In situ symbiotic germination is a relatively recent technique that has evolved over time and continues to be with increased interest and research in this area. This review article is an attempt to provide an overview of symbiotic seed germination in orchids- exsitu and in situ techniques.