Abstract

In recent decades, in vitro propagation has benefited from the use of light-emitting diodes (LEDs), whose spectral quality directly influences plant development. This study evaluated the effect of different light spectra on the in vitro germination of Cattleya crispa Lindl., an orchid species endemic to Brazil with high ecological importance. For 70 days, seeds were cultivated in MS medium under four lighting treatments: blue, red, white, and a blue+red LED combination, using fully sealed flasks. The variables analyzed were germination rate, number of oxidized protocorms, protocorms with leaf primordia, and fresh biomass of the seedlings. Red light resulted in the highest germination rate (86.55%), an effect possibly related to the activation of phytochromes and the induction of gibberellin biosynthesis, both essential for breaking seed dormancy. C. crispa seeds exhibited positive photoblastism, with greater sensitivity to red light. On the other hand, blue light favored the highest accumulation of fresh biomass (0.87 g per experimental unit) and the greatest formation of protocorms with leaf primordia, standing out in the initial growth of seedlings. The combination of blue and red LEDs promoted balanced morphogenesis, optimizing the formation of photosynthetic structures. Red light was also associated with higher oxidation levels, suggesting increased oxidative stress, whereas seeds cultivated under blue light exhibited lower oxidation rates, likely due to the activation of antioxidant mechanisms that protected the protocorms. It is concluded that blue light, either alone or combined with red light, provides better conditions for micropropagation, supporting the conservation and commercial production of C. crispa, an orchid species of great ecological and ornamental value.

Keywords

Cattleya crispa, in vitro germination, LEDs, phytochrome, protocorm