Different levels of irradiance and plant regulators modify the leaf structure and essential oil production of Lippia origanoides H.B.K (Verbenaceae)

The quality and quantity of secondary metabolites produced by plants can be influenced by biotic and abiotic factors, since the biochemical and physiological processes that coordinate the synthesis of these compounds are influenced by these. Plant regulators can also interfere with plant growth and terpene biosynthesis in aromatic species, which is why they are widely used in agriculture. Lippia origanoides H.B.K is an aromatic shrub that has glandular trichomes on the leaf, which secrete and accumulate essential oil used in the production of culinary seasonings and in the cosmetic and pharmaceutical industry. The objective of this research was to evaluate the effects of plant regulators associated with different levels of light availability in L. origanoides exposed to levels of 100, 50, 35 and 25% of irradiance. The increase in irradiance in plants treated with plant regulator caused changes in the structure and leaf dry biomass, density of glandular trichomes and essential oil content in the 100% full sun treatment. The treatments did not influence the chemical profile of the essential oil, which presented thymol as the major component. However, the application of bioregulators in full sun increased the production of essential oil demonstrating an excellent option for increasing the production.