Asymbiotic Germination, Effect of Plant Growth Regulators, and Chitosan on the Mass Propagation of Stanhopea hernandezii (Orchidaceae)

Abstract

Background: Stanhopea hernandezii was collected from natural habitat in Mexico for its beautiful fragrant flowers. Biotechnological strategies of propagation may satisfy the market demand and are useful for conservation programs.
 Hypothesis: Vigorous seedlings of S. hernandezii can be produced in vitro by asymbiotic seed germination techniques and the addition of chitosan to the culture medium in the temporary immersion system (RITA®) and in semi-solid medium systems.
 Methods: The first step was the in vitro germination of seeds obtained from a mature capsule of wild plants, followed by multiplication via adventitious protocorm induction known as protocorm-like bodies, using plant growth regulators. For this purpose, we utilized Murashige and Skoog (MS) basal medium amended with 0.5 mg/L ?-Naphthaleneacetic acid, combined with different concentrations of 6-Benzylaminepurine (1, 3, and 5 mg/L). The following step comprised the growth and development of protocorms to obtain plantlets in RITA® flasks containing 250 mL of liquid MS medium combined or not with different chitosan concentrations (5, 10, 15, 20, and 25 mg/L).
 Results: The results showed that media supplemented with 5, 10, and 15 mg/L chitosan concentrations enabled the obtaining of a larger biomass with a range of 40-48 seedlings/RITA® and an average height of 13 mm. The last step was the development from seedlings into plantlets, the latter being, vigorous and achieving up to 100 % survival after 12 weeks of ex vitro cultivation.
 Conclusion: This paper describes an efficient process of asymbiotic germination and mass propagation of S. hernandezii, a vulnerable orchid species endemic to Mexico.

Auxins and Cytokinins elicit a differentiated response in the formation of shoots and roots in Cattleya maxima Lindl and Phalaenopsis amabilis (L) Blume

“…In addition, orchids have a long production period, and, for this reason, other methods are applied for its development and conservation. In vitro culture or micropropagation is the most used alternative for orchids propagation (Freitas et al, 2021), being applied in the stages of germination, seedling growth and rooting; especially for commercial species (Arellano et al, 2020;Cardoso et al, 2020). For this purpose, culture media are used, sometimes complemented with organic substances like banana flour, coconut water and others (Salazar & Botello, 2020;Wida & Hariyanto, 2020) or growth regulators (Parthibhan et al, 2015), to provide the physiological stimulus necessary for their development.…”