Organic Compounds: Contents and Their Role in Improving Seed Germination and Protocorm Development in Orchids

Abstract

In nature, orchid seed germination is obligatory following infection by mycorrhizal fungi, which supplies the developing embryo with water, carbohydrates, vitamins, and minerals, causing the seeds to germinate relatively slowly and at a low germination rate. The nonsymbiotic germination of orchid seeds found in 1922 is applicable to in vitro propagation. The success of seed germination in vitro is influenced by supplementation with organic compounds. Here, we review the scientific literature in terms of the contents and role of organic supplements in promoting seed germination, protocorm development, and seedling growth in orchids. We systematically collected information from scientific literature databases including Scopus, Google Scholar, and ProQuest, as well as published books and conference proceedings. Various organic compounds, i.e., coconut water (CW), peptone (P), banana homogenate (BH), potato homogenate (PH), chitosan (CHT), tomato juice (TJ), and yeast extract (YE), can promote seed germination and growth and development of various orchids. They also stimulate seedling development, formation of protocorm-like bodies (PLBs), plantlet growth, and multiple shoot formation. The addition of organic compounds to culture media, individually or in combination, accelerates seed germination and seedling development. Different types and concentrations of organic nutrients are needed for the success of in vitro cultures, depending on the species and genotype.

Dendrobium sp.: In vitro Propagation of Genetically Stable Plants and Ethnomedicinal Uses

“…A defined culture medium contains minor and major inorganic salts, carbon source, amino acids, and several vitamins. However, as per requirement, the culture media can be incorporated with organic acids, organic nitrogenous compounds, and other plant extracts [95,96]. Normal media consist of few mineral salts with 30 mM each of inorganic nitrogen and potassium, and ammonium salts at the range of 2-20 mM.…”

Effect of Coconut Water and Peptone in Micropropagation of Phalaenopsis amabilis (L.) Blume Orchid

“…Sugars, amino acids, vitamins, enzymes, and organic acids were found in coconut water, which influenced the growth of P. amabilis (L.) Blume Orchid leaves. According to Utami and Hariyanto [13], the treatment that supplements with peptone shows a positive result in the multiplication of shoots and leaves since it contains high amounts of vitamins and amino acids, including thiamine, biotin, nitrogen, and pyridoxine.…”

The challenges of growing orchids from seeds for conservation: An assessment of asymbiotic techniques

“…Instead, we aim to report on what has been used successfully by researchers in controlled experimental studies of asymbiotic germination. Several excellent papers by Malmgren (1996), Kauth et al (2008), Park and Yeung (2018), Yeung et al (2018), and Utami and Hariyanto (2020) provide details of specific techniques and the benefits and consequences of individual media and supplements. We hope that our review contributes to this vast body of literature on propagating orchids from seed and further stimulates botanists to engage in experiments that determine optimal conditions for asymbiotic germination of native orchids, particularly for those species that face severe threats to their continued existence due to loss of habitat, herbivory, low reproduction, and illegal collection.…”