In vitro culture of Mentha viridis: quality and intensity of light on growth and production of volatiles

Mentha viridis (Lamiaceae) has a great potential for economic exploration due to its essential oil production, which is widely used in chemical and pharmaceutical industries. The aim of this work was to study the effect of light spectra, in the presence and absence of growth regulators (BAP), and light intensity on M. viridis growth and production of volatile compounds under in vitro conditions. Nodal segments from prior established in vitro cultured plants were placed on solidified MS medium in the presence and absence of BAP under different light-emitting diodes (LED): blue; red; blue:red at proportions of (2.5:1) and (1:2.5); and fluorescent light. The explants were also exposed to a photosynthetic photon flux density (PFD) of 28, 51, 64, 76 and 113 μmol m(-2) s(-1) using a cool fluorescent light. After 30/40 days of culture, growth and production of volatiles of the plants was verified by Head-Space - GC/MS. Blue and red LED combinations promoted the growth of plantlets significantly. The presence of BAP negatively affected plantlet growth. PFD affected plantlet growth and morphological characteristics of M. viridis. The rise in light intensity promoted a higher accumulation of dry matter of leaves and total plant. The production of volatile compounds was affected both in quality and quantity by light conditions applied in this experiment. Therefore, the manipulation of spectrum and light intensity in in vitro culture environment, might be a strategy for the production of compounds of interest to industries.