Crescimento in vitro e estabelecimento ex vitro de Shomburgkia crispa Lindl. e Cattleya walkeriana Gardner em sistemas modificados de micropropagação

Abstract

The production of native orchids is one of the factors that can contribute to the reduction of extractivism. This work sought to contribute to the enhancement and preservation of the native flora of orchids, through in vitro cultivation techniques and acclimatization in a screened nursery. To achieve the proposed objective, two independent experiments were carried out: I- with the aim of evaluating the influence of two sealing systems and eight light sources on in vitro growth and ex vitro establishment of Shomburgkia crispa Lindl. For the beginning of the experimental period, plants with 120 days of in vitro culture were subcultured in MS culture medium, with four plants per culture flask being inoculated. Then, half of the bottles were closed in a conventional sealing system (SVC) and the other half in a gas exchange sealing system (SVTG). The cultures were then placed under the light sources: 100% white LED; 100% blue LED; 100% red LED; LED 50% white + 25% red + 25% blue; 50% red LED + 50% blue LED; LED 25% red + 75% blue; 75% red LED + 25% blue LED and as a white fluorescent lamp control. After the experimental period (in vitro cultivation = 120 days and ex vitro cultivation = 180 days), the plants were evaluated for the number of leaves, number of roots, plant height, diameter of the pseudobulb, number of shoots, length of the largest root , length of the largest leaf and fresh mass. The use of the gas exchange sealing system in conjunction with light sources in the combination of blue and red wavelengths, in different proportions, favors the in vitro cultivation of S. crispa. For ex vitro establishment, plants grown in vitro in a system that allows gas exchange together with the LED 50% white + 25% red + 25% blue, positively influences the acclimatization of the plants; II - carried out in order to evaluate the effect of the formulation of the culture medium, the sealing system of the flasks and the irradiance provided by 3000K LED lamps on in vitro growth, survival and ex vitro establishment of Cattleya walkeriana Gardner. As culture medium, the following media were used: MS (control); MS supplemented with 150 g L-1 of banana pulp; MS with 300 g L-1 of banana pulp; MS with 150 g L-1 of banana peel; and MS with 300 g L-1 of banana peel. After inoculation of the plants in an aseptic environment, half of the flasks were sealed in SVC and the other half in SVTG, and placed under two irradiances provided by 3000K LED lamps: 86 μmol m-2 s -1 or 128 µmol m-2 s -1 . The characteristics evaluated were the same as in experiment I, including the number of pseudobulbs. The use of the medium plus banana pulp in up to 150 g L-1 together with the irradiance of 128 µmol m-2 s-1 and SVC provided the highest values for the in vitro growth of the plants. For ex vitro cultivation, the MS medium, together with the irradiance 86 μmol m-2 s-1 , provided the greatest survival and establishment of plants of this species. With the results obtained in both experiments, it was verified that the supplementation of the culture medium with banana pulp, different sealing systems of the flasks and light conditions can benefit the production, contributing to the valorization and preservation of the studied species.