Improvement of biomass and essential oil production of Lippia alba (Mill) NE Brown with green manures in succession

The objective of this work was to evaluate the biomass production, yield and composition of essential oil from Lippia alba (Mill) N.E. Brown, cultivated in succession with green manures. The experiment was conducted in the field with five treatments: T-1 sunn hemp (Crotalaria juncea L.); T-2 velvet-bean (Mucuna aterrima Holland); T-3 cowpea (Vigna unguiculata L. Walp); T-4 spontaneous plants; and T-5 control. Lippia alba essential oils were chemically characterized by gas-chromatography with mass spectrometry detector (GC/MS) at two harvest moments (120 and 262 days after transplantation). The application of green manures, mainly velvet-bean, increased biomass and essential oil production, mainly in the second harvest (total oil yield of 62.43 L ha(-1)). The main volatile compounds identified in the essential oil (beta-myrcene, germacrene D, limonene, and carvone) didn't suffer significant changes in function of the treatment applied. However, all the compounds mentioned report a higher yield in L alba plants cultivated with velvet-bean (except germacrene D). Compared to control treatment, beta-myrcene, limonene, and carvone increased 1.3%, 4.2%, and 6.6% with velvet-bean. The use of velvet-bean as green manure is a cheap resource that causes a positive effect in the cultivation of L alba plants and may reduce the use of chemical fertilizers, being an eco-friendly strategy for the cultivation of medicinal plants.