LIGHT QUALITY IN THE IN VITRO INTRODUCTION OF Corymbia HYBRID CLONES

ABSTRACT Micropropagation via axillary bud proliferation is recommended for rejuvenation or reinvigoration of selected clones, as well as for improving clonal seedlings rooting. The success of a micropropagation protocol depends on the in vitro introduction, since following phases, multiplication, elongation, and rooting can only take place once the aseptic crop with vegetative vigor has been established. This study aims to assess the effect of light on the in vitro introduction of hybrid clones of Corymbia torelliana x C. citriodora e Corymbia citriodora x C. torelliana by the micropropagation technique through proliferation by axillary buds. The mini-stumps, suppliers of explants for in vitro introduction, were conducted in semi-hydroclonal mini-clonal hedge. Nodal segments from three Corymbia torelliana x C. citriodora (TC01, TC02 e TC03) clones and one Corymbia citriodora x C. torelliana (CT01) clone were collected, disinfested and inoculated in JADS culture medium, in order to compare the effects of light quality from a dark/fluorescent lamp, a fluorescent lamp, and white and red/blue LEDs. At 30 days after inoculation, the following characteristics were evaluated: average contamination percentage, oxidation, non-reactive explants, shoot length and average number of shoots per explant greater than 0.5 cm. Gathered data showed that the use of red/blue LED light source obtained the best results in all assessed characteristics in the in vitro introduction.