Pfaffia glomerata (Spreng.) Pedersen is an extensively used plant in popular medicine due to its phytotherapic characteristics. Due to low photosynthetic capacity of plants cultivated in vitro, an extra source of carbohydrates is required to supply their metabolic demands. The growth rate of roots and shoots of P. glomerata are different during the in vitro cultivation. The objectives of this study were to evaluate the effect of sucrose levels and the duration of in vitro growth on ex vitro acclimatization of P. glomerata seedlings. Treatments consisted of a bifactorial combination (5x2) of five sucrose levels (15, 30, 45, 60 and 75g L-1) and two periods of in vitro cultivation (25 and 32 days after inoculation). In the in vitro cultivation, the experimental unit consisted of a test tube containing 10mL of MS medium and a nodal segment, from in vitro cultivated plants, of 1,0cm in length without leaves. The acclimatization scheme consisted of ex vitro cultivation by four successive phases: (i) opening of the test tube and subsequent cultivation in growth room for three days; (ii) seedlings subcultivation to Plantmax substrate and cultivation in growth room for 21 days; (iii) seedlings transfer to partially shady natural environment for 24 days; and (iv) seedling subcultivation to soil under field condition. The greatest plant growth by increasing the sucrose availability (levels among 45 and 60g L-1) during the in vitro growth contributed to acclimatization. Regardless of duration of the in vitro growth, the seedlings obtained and efficient acclimatization. The acclimatization procedure was 100% efficient on seedling production of P. glomerata.
micropropagation; carbohydrate; seedling production; autotrophy; heterotrophy
