Organo-mineral fertilization effects on biomass and essential oil of lavender (Lavandula dentata L.)

Large-scale production of aromatic plants is subject to phytotechnical challenges, such as management, irrigation, nutrition, and soil fertility, as well as exogenous issues that may affect the chemical composition of secondary metabolites. The aim of this study was to evaluate the effect of organo-mineral fertilizer on the biomass and essential oil of lavender (Lavandula dentata L.). A randomized block experimental design was used in a split-plot arrangement, consisting of five rates of organo-mineral fertilizer, and an additional treatment with only mineral fertilizer. The organo-mineral fertilizer was used at the same recommended rate as the mineral fertilizer. The organo-mineral fertilizer was formulated with 10% total nitrogen, 10% P2O5, 10% total potassium, and 8% organic carbon, and was applied at the following rates: 100%, 80%, 60%, 40%, and 20%. Flowers, leaves, and stems were harvested three times. Plant biomass, and the concentration, yield, and chemical composition of the essential oils were evaluated. Results showed that the highest flower yield was obtained at 145 days after planting through use of the 100% rate of the organo-mineral fertilizer. The 60% rate of the organo-mineral fertilizer produced more than 320 g plant−1 of fresh biomass. The major compounds were 1,8-cineole, camphor, and fenchone, and these compounds together represented more than 80% of the chemical composition. The organo-mineral fertilizer can ensure greater yield through slow release of nutrients around the root system, especially at the flowering stage. We conclude that associating organo-mineral fertilization with the appropriate harvest season has a noticeable impact on the chemical composition of lavender essential oil.