In vitro germination of Adenium obesum under the effects of culture medium and light emitting diodes of different colors

Abstract

Adenium obesum seeds germinated and in vitro cultivated under lighting with different wavelengths of light from light emitting diodes (LEDs) (white LED—6400 K—λ = 525 nm; blue LED—λ = 430 nm; green LED—λ = 520 nm; orange LED—λ = 595 nm; purple LED—λ = 440 nm “2 blue LEDs + 1 red LED”; and red LED—λ = 670 nm) and control—absence of LED, combined with different culture media (MS and MRA). This work aimed to evaluate the influence of LED lighting conditions and culture media on seed germination, initial in vitro growth of A. obesum seedlings and production of photosynthetic pigments and soluble sugars. The study demonstrated a significant effect of red LED light combined with MRA medium and purple LED combined with MS medium, promoting the highest germination rates and the lowest mortality rates. The best initial in vitro development of A. obesum seedlings occurred under red LED in both culture media, which generated positive changes in the morphological variables analyzed. The highest pigment contents were obtained by combining white light with MS medium and green light with MRA medium. This is the first report to provide evidence of the stimulating effect of light quality on germination, early growth, production of photosynthetic pigments by A. obesum seedlings in vitro.