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ABSTRACT. The effects of different light quality treatments on in vitro growth and multiplication of sugarcane (RB867515) were investigated. The plantlets were cultivated on MS medium containing 1.3 μM 6-benzylaminopurine (BAP), and exposed to five light treatments: three combinations of blue/red LED (70:30, 50:50, 30:70), white-LED and fluorescent lamps, during 24 days. Among the LED light treatments, blue/red combination in 50:50 proportions proved to have the best results for stem length, fresh mass, leaf number and shoot multiplication. Higher content of photosynthetic pigments was also obtained with LEDs. Results suggested that the light quality emitted by LEDs was suitable for plant growth and development and it may be used as alternative and economic light source for micropropagation of sugarcane variety under analysis.Keywords: in vitro propagation, light wavelength, Saccharum spp.Efeito da qualidade espectral da luz no cultivo in vitro de cana-de-açúcar RESUMO. Foram investigados os efeitos de diferentes tratamentos de qualidade da luz sobre o crescimento e multiplicação in vitro de cana-de-açúcar (RB867515). As plantas foram cultivadas em meio MS contendo 1,3 μM de 6-benzilaminopurina (BAP) e expostas a cinco tratamentos de luz: três combinações de LED azul/vermelho (70:30, 50:50, 30:70), LED branco e lâmpadas fluorescentes, durante 24 dias. Entre os tratamentos de luz de LED, a combinação azul/vermelho na proporção 50:50 apresentou os melhores resultados para altura, massa fresca, número de folhas e multiplicação de brotos. Maior teor de pigmentos fotossintéticos também foi obtido com a utilização de LEDs. Os resultados sugerem que a qualidade da luz emitida pelos LEDs foi adequada para o crescimento e desenvolvimento das plantas e pode ser utilizada como fonte de luz alternativa e econômica para a micropropagação da variedade de cana-deaçúcar estudada.Palavras-chave: propagação in vitro, comprimento de onda da luz, Saccharum spp.

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The influence of two aromatic cytokinins (CKs), 6-benzylaminopurine (BAP) and meta-topolin (mT), on in vitro propagation and redox metabolism of sugarcane (Saccharum spp., variety RB98710) was investigated. Plants were cultured in Murashige and Skoog (MS) medium supplemented with mT (5 µmol.L-1) or BAP (5 or 6.66 µmol.L-1) for 40 days. The use of mT provided an increase in the multiplication rate and stem length of plants and shoots when compared to BAP. Shoots generated from the mT treatment presented low malondialdehyde (MDA) content and superoxide dismutase (SOD) activity, although they had higher hydrogen peroxide (H2O2) content. Thus, the H2O2 did not act as a stress marker, but it is related to plant growth and development processes.