Review Article Journal of Scientifc Enquiry Vol: 1, Pages: 1-7 A Review on Asymbiotic Seed Germination in Orchids through Plant Tissue Culture Purnima Paramanik 1 , Dipak Kumar Kar 2* and Subrata Raha 3* 1,3 Department of Botany, Sidho-Kanho-Birsha University, Purulia, W.B. – 723104, India. 2 Vice-chancellor, Sidho-Kanho-Birsha University, Purulia, W.B. – 723104, India. Received: 09.11.2021; accepted: 06.12.21; published online: 30.12.2021 Orchid seeds are very small, dust like in appearance, fusiform in shape, lacking endosperm and have undiferentiated embryo covered by transparent seed coat. Mycorrhizal association is required for seed germination of naturally growing orchids. In this symbiotic association, orchid species are dependent on mycorrhizal association for supply of mineral nutrients. In in-vitro condition, such demand of minerals may be compensated by external supply of sugar and mineral nutrients that are required for seed germination of orchid. Several orchids are responded by this asymbiotic seed culture and have commercial importance. Therefore, formulation of effcient in-vitro protocol is important for commercially important orchid species as well as endangered orchid species for conservation. This review paper is focused on various aspects of asymbiotic seed germination of orchids and the role of organic additives in successful seed germination. Key words: Orchids, asymbiotic seed germination, media, in-vitro culture, organic additives. 1. Introduction Plant tissue culture has a long history. History of plant tissue culture is based on reviews by Kriko- rian and Berquam[1], Gautheret [2], Bhojwani and Razdan [3], Gamborg [4], Dodds and Roberts [5], Trigiano and Gray [6], and Vasil [7]. Thousands of commercial orchids (family: Orchidaceae) are mainly grown in-vitro for their beautiful fowers and medicinal importance. It is estimated that about 28000 species of orchid belonging to 736 genera under family Orchidaceae occur worldwide [8 and 9]. This is the largest and highly evolved family of fowering plants [10]. Seventy percent of orchids are epiphytes which constitute around two-third of the world’s epiphytic fora [11]. Of 1100 species, nearly 150 are economically impor- tant in India, representing one of the major orchid- rich regions [12]. Orchid has highly specialized pollination mechanism and also have small, thin and non-endospermic seeds. Symbiotic associa- tion with mycorrhizal fungi is required for orchid seed germination in their natural habitats [13]. Orchids are diverse with universal habitats and have extraordinary mechanism of adaptation to persist in adverse environmental conditions [13, 14, and 15]. Most of the time orchids charmed botanists, horticulturists, and evolutionary biolo- gists. Propagation of orchids via seed germination ∗ Corresponding authors Emails: vc.skbu@gmail.com (Dipak Kumar Kar); subrata-raha@skbu.ac.in (Subrata Raha) has a long history. The large-scale production of orchids in nature through conventional horticul- tural methods is quite diffcult due to their slow growth rate and poor rate of seed germination under natural conditions [16 and 17]. Moreover, growth of orchids is enhanced by specialized mi- croclimatic condition and by the protective canopy of the plants in their natural habitats [18]. De- mand of orchids has been commercially increasing day by day. As a result, the rapid propagation of orchids totally depends upon the development of in-vitro techniques [16 and 17]. Therefore, in- vitro mass propagation techniques are widely prac- ticed for conservation and commercialization of orchid species. Asymbiotic seed germination pro- tocol techniques were developed by Knudson and Knudson C medium formulated by him in 1946 [19] is still used today. This medium is also used for propagation of a variety of terrestrial and epi- phytic orchid species. The aim of this review is to summarize the knowledge about asymbiotic seed culture of orchid and the common media that are used in orchid seed germination. Diferent addi- tives are also used for enhancement of seed ger- mination of orchids like coconut water, peptone, banana extract, potato extract, charcoal, yeast ex- tract, case in hydrolysate etc. 2. Orchid Seeds Orchid seeds are extremely small (0.05–6.0 mm in length and 0.01–0.9 mm in diameter), very much DOI: https://doi.org/10.54280/21/05 © 2021 Sidho-Kanho-Birsha University J. Sci. Enq., 2021, 1(1) 1