Resumo

MURILLO-TALAVERA, Martha M. et al. Led light quality and in vitro development of Oncidium tigrinum and Laelia autumnalis (orchidaceae). Agrociencia [online]. 2016, vol.50, n.8, pp.1065-1080. ISSN 2521-9766.

Quality, intensity and duration of light affect plant development because they promote different physiological responses. The aim of this study was to evaluate the influence of different lighting spectra on in vitro development of Oncidium tigrinum La Llave and Lex. and Laelia autumnalis (Lex.) Lindl. Three-month-old seedlings were grown in a Murashige and Skoog medium without plant hormones plus thiamine (0.4 mg L-1), inositol (100 mg L-1), saccharose (30 g L-1), and agar (6 g L-1) with pH of 5.7. The experimental design was completely randomized and the experimental unit consisted of 30 seedlings. Treatments were red and blue LEDs in a 3:1, 2:2, and 1:3 ratios, white LEDs and fluorescent white light (control), with six repetitions per treatment. Wave lengths were: 590-670 nm for red, 430-480 nm for blue, and 400-700 nm for white; photosynthetically active radiation was adjusted to 31±2 µmol m-2 s-1. The dependent variables were seedling and root length, number of leaves and roots, fresh and dry matter, and a, b and total chlorophyll content. An ANOVA was performed with this data and means were compared with a Tukey test (p(0.05). Results showed that white LED lighting was similar to fluorescent lighting in terms of in vitro seedlings development of L. autumnalis. Seedlings showed twice as much a, b, and total chlorophyll and up to 2 % more biomass accumulation compared with the other treatments. For O. tigrinum, white LED light induced the development of vigorous bright green plants with no photooxidation damage. LEDs lights were confirmed as an effective alternative for in vitro seedling growth and development of O. tigrinum and L. autumnalis.

Palavras-chave : Laelia autumnalis; Oncidium tigrinum; in vitro development; in vitro directed radiation; LEDs.

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