Germination, growth and morpho-anatomical development of Catasetum macrocarpum (Orchidaceae) in vitro

Abstract

Catasetum macrocarpum is an epiphytic orchid that has been subjected to strong environmental pressure in the state of Tocantins. This investigation aimed at studying the germination, growth and morpho-anatomical development of C. macrocarpum under in vitro conditions. The effects of three culture media on the in vitro germination and on the multiplication and growth of 90-day-old seedlings were studied: Murashige & Skoog (full- and half-strength), Knudson C, and Vacin & Went. The effects of different concentrations of benzyladenine (BA) and naphthaleneacetic acid (NAA) on the multiplication and growth of 120-day-old plants were evaluated. Anatomical studies were conducted on protocorms at different developmental stages. Acclimatization was also carried out. Knudson C was the best medium for seed germination whereas Vacin & Went promoted the greatest protocorm development. Half-strength Murashige & Skoog was the most effective medium for seedling multiplication and growth. The results revealed that 1 mg L-1 BA was the best treatment for shoot proliferation and leaf production. NAA at 0.5 mg L-1 strongly favored root formation. The anatomical study revealed that the early stages of C. macrocarpum development do not always coincide with the morphological phases described. The acclimatization of C. macrocarpum plants provided successful results regarding plant survival.

Commercial fertilizers and organic additives in orchid micropropagation

“…The T3 medium (BU) contributed less effectively to the formation of the root system (3.52 mm), although the length of the main roots and their respective diameters do not vary significantly concerning the other media (Table 2). Ferreira et al (2018) indicated to Ctsm. macrocarpum that each developmental stage for this specie requires a different culture medium with specific nutrient concentrations.…”

“…For seeding, about 40 mg of seeds were disinfected with 0.4% sodium hypochlorite for five min and rinsed three times with sterile distilled water (Alvarez-Pardo;Ferreira;Nunes, 2006). The seeds were kept in water and distributed in 500 mL jars containing 100 mL of medium, four jars per treatment for each species.…”

“…Of relatively easy cultivation, Catasetum is known for its exotic beauty flowers, providing an essential economic position in the floristic market. However, Catasetum species with great economic potential have been extracted from their habitat, compromising their natural reproduction and survival (Ferreira et al, 2018).…”

“…Catasetum macrocarpum Rich. ex Kunth, occurs in the Amazon, Cerrado and Atlantic Forest, vegetating Anthropic Area, Campinarana, Rupestre Field, Cerrado (lato sensu), Ciliary Forest or Gallery, Igapó Forest, Terra Firme Forest, Várzea Forest, Seasonal Semideciduous Forest, Forest Ombrófila, Restinga, Amazonian Savanna (Barros et al, 2015) and is subject to intense environmental pressure in some of these areas (Ferreira et al, 2018).…”

“…Traditional culture media is used for in vitro propagation of numerous species, and different responses are observed due to the nutritional specificity in each orchid genus or even species (Cunha et al, 2011;De Freitas et al, 2014;Ferreira et al, 2018;Parthibhan;Rao;Kumar, 2015;Paul;Kumaria;Tandon, 2012).…”