The objective of this work was to evaluate the effect of colchicine, when applied at different times on O. flexuosum protocorm differentiation. Peracetic acid was previously tested at 0, 3, 6 and 9 mL L-1 concentrations for 10 days, in order to verify the efficacy on the culture medium sterilization and the possible phytotoxic effects on protocorms. After determining the concentration, 6 mL L-1 of peracetic acid were added in MS medium with 0.05% colchicine and DMSO 1%. The protocorms were agitated during 0, 24, 48, 72, 96 and 120 hours. The experimental delineation used was the completely randomized blocks, with 6 treatments, 10 repetitions and 5 protocorms per repetition. Thirty days after the treatment began, protocorm survival rates were assessed; after 180 days, the following were assessed: number of buds, aerial part height, number of roots, the length of the largest root and plantlet fresh mass. The data were submitted to regression analysis. Peracetic acid in the concentration of 6 mL L-1 can be used as a substitute for the colchicine solution filtration process. The increase in colchicine exposure time caused a rise in the number of dead protocorms.
Orchidaceae; polyploidy; phytotoxicity; sterilization
