Seed viability test of orchids native to the Brazilian Savanna

An essential factor for the formation of a native orchid seed bank is the identification of the viability of stored seeds. This study aimed to determine a methodology for optimizing the tetrazolium test, in the identification of the viability of stored seeds of two Orchidaceae medicinal species native to the Brazilian Savanna. Seeds of Miltonia flavescens Lindl. and Schomburgkia crispa Lindl. were submitted to three pre-conditioning conditions: no soaking (control), sucrose solution or distilled water. The seeds were then submitted to a tetrazolium solution, with three types of conditioning: oven, water bath or ambient temperature. The M. flavescens seeds showed a germination of 86.91 %, with a higher percentage of viable seeds (62.32 %) when submitted to pre-conditioning with sucrose + oven conditioning. For S. crispa, the germination was 97.78 %, with a higher percentage of viable seeds for the control treatment + ambient temperature (89.49 %). These results suggest that specific protocols should be used to conduct the tetrazolium test in Orchidaceae. Moreover, when performed on a sample basis, the tetrazolium test should only be used to indicate the seed viability.