摘要：

Acclimatization, which involves the transfer of in vitro cultivated plants to ex vitro conditions, is a critical stage in micropropagation. The choice of an appropriate substrate can affect plant survival rates. The objective of this study was to evaluate the efficiency of different substrates on the acclimatization of in vitro propagated Miltonia flavescens. Plantlets obtained from in vitro culture were transferred to polypropylene pots containing five different substrates: coconut fiber powder, coconut fiber, Pinus sp. bark, coconut fiber powder blended with Pinus sp. bark and Plantmax®. The experimental unit consisted of one pot containing two plants, with ten repetitions, totalizing 20 plants per treatment. At 30, 60 and 90 days after transplanting the plants were evaluated for survival rates, and after 90 days, shoot and root lengths were evaluated. No significant difference was found among treatments after 30 days of cultivation. At 60 days after transplanting, a marked decrease in survival rate was recorded for all substrates. The highest rates were obtained with coconut fiber, with significant difference only in relation to coconut fiber powder and this performance was sustained at 90 days of cultivation. The highest vegetative growth was recorded for the substrate Pinus sp. bark.

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