In vitro behaviour of Aspasia variegata, an epiphytic orchid from the Brazilian Cerrado

Abstract

Aspasia variegata occurs naturally in the savanna of the Mato Grosso do Sul State, Brazil and it has been widely collected for its beautiful flowers. Additionally, its habitat has been greatly reduced and little or no investigation of its spread has been performed. Aiming to establish a protocol to obtain seedlings of the orchid A. variegata, different compositions of culture medium were tested to identify which one provided better in vitro growth and development and to assess the influence of these media in seedling acclimatisation. Thus, seeds obtained from mature capsules were inoculated in Knudson culture medium for 120 days until the protocorm stage. They were transferred to different culture media formulations, including MS and Knudson with half or full formulation, and 3.0 and 6.0g L-1 activated charcoal were added to them or not. After 180 days of protocorm inoculation, seedlings were evaluated for length of roots and shoots, number of roots and leaves, and chlorophyll contents. After that, seedlings were transferred to trays containing a mixture of Plantmax® and coconut fibre (1:1) for acclimatisation. Best results for the in vitro growth of A. variegata were obtained with the use of MS medium supplemented with 6.0g L-1 activated charcoal. Higher levels of chlorophyll were obtained, however, in treatments containing MS salts without activated charcoal presence, and lower levels in media containing Knudson salts with the presence of activated charcoal. The seedlings originated by higher chlorophyll levels during in vitro cultivation presented the highest survival rates and better development in the acclimatisation phase.