Optimal conditions for in vitro culture of Cattleya cernua, a small orchid native of Atlantic Forest and Cerrado

Abstract

Cattleya cernua is an epiphytic orchid native of the Atlantic Forest, Cerrado, Caatinga and Pampa. Aiming at the development of an in vitro conservation technology, plants were micropropagated through asymbiotic culture and the influence of different concentrations of sucrose (10, 30, 60 and 90 g L^-1) and macronutrients (25, 50 and 100% MS) on survival and development was evaluated. Plant survival ranged between 47 and 100%. The interaction between macronutrients and sucrose influenced plant development. The aerial system of the plants was higher in 100% MS medium combined with 30 or 60 g L^-1 of sucrose. The number of roots was higher with reduced macronutrients, combined with 30 or 60 g L^-1 of sucrose. The length of the largest root was also higher when macronutrients were reduced but combined with 10 or 30 g L^-1 of sucrose. The greatest mass was recorded when 30 g L^-1 of sucrose was added to the three salt concentrations. Chlorophyll did not differ between plants grown with 30 or 90 g L^-1 of sucrose. We recommend cultivating the plants in MS medium with 30 g L^-1 of sucrose for better development of the aerial system. C. cernua can be asymbiotically micropropagated, facilitating ex vitro conservation strategies.

Key words:
carbon source; conservation; in vitro culture; nutrients; orchid