Asymbiotic culture of Cattleya intermedia Graham (Orchidaceae): the influence of macronutrient salts and sucrose concentrations on survival and development of plantlets

Abstract

Cattleya intermediais an Atlantic Forest species endemic to Brazil that is classed as vulnerable on the list of threatened species. In this study, C. intermedia plantlets were micropropagated in an asymbiotic culture and the influence of different concentrations of sucrose (15, 30, 45 and 60 g L-1, plus a zero sucrose medium) and macronutrient salts (complete Murashige and Skoog (MS) medium and half MS medium (with half-strength macronutrients)) on survival and development of the plantlets was evaluated. In all treatments 100% plantlet survival was achieved. The integrated analysis of height of aerial part, number of leaves per plantlet, fresh mass, number of roots per plantlet and length of the longest root showed that the plantlets exhibited greatest development at the half-strength macronutrient concentrations with 45 or 60 g L-1 of sucrose, as well as at the complete macronutrient concentration with 60 g L-1 of sucrose. Plantlets acclimatized and reintroduced to an environment in which the species occurs naturally exhibited 98.6% survival. The results obtained in this study allowed the establishment of optimal conditions for asymbiotic micropropagation, which is a requisite for future studies focused on conservation of C. intermedia.