EFFECTS OF LED-ILLUMINATION AND LIGHT INTENSITY ON THE ACCLIMATIZATION OF IN VITRO PLANTLETS TO EX VITRO CONDITIONS

Abstract

The aim of this study was to evaluate the suitability of ready-made light emitting diodes (LED) in the acclimatization process of in vitro regenerated plants from somatic embryos to ex vitro. At which the fluorescent tubes (FL) represented the reference. The plantlets were cultured for six weeks under two ready-made LED systems with different wavelength combinations: BloomPower white lamps (LED (BP)) at 300, 90, or 50 µmol m-2 s-1 and tubes of Valoya at 90 µmol m-2 s-1 together with fluorescent tubes (FL) at 90 µmol m-2 s-1 as reference. To verify the physiological state of the adapted plants six of each treatment were potted and cultured for further 60 days under former light conditions. Over all light conditions only 28.7% of the investigated plants with embryogenic origin could be well adapted. Most of them acclimatized under LED (BP) 300 and FL 90. Thereby LED (BP) 300 showed the highest biomass accompanied by shortest shoot and internode length, strong plants but with red colored leaves. Even after adaptation potted plants showed the same pattern. Indirect measurement of flavonols via Dualex indicated high stress level. The results indicated that the acclimatization of plants regenerated from somatic embryos is very susceptible against environmental alteration but 90 µmol m-2 s-1 seemed to be sufficient for proper plant development. The lower growth parameters resulted in the different wavelength compositions of the LED tubes as compared to fluorescent tubes and have to be optimized.