Exogenous utilization of jasmonic acid and methyl jasmonate stimulates growth and biochemical composition of lavender (Lavandula angustifolia) plant

Background
Lavender (Lavandula angustifolia) as an economic herb is used in traditional medicine, perfume, flavoring, and cosmetics. It is classified in the mint family (Lamiaceae) and commonly used as a landscape plant. Monoterpenes and sesquiterpenes are the most common chemical components found in essential oils. Because of these compounds, it is used for antifungal, antibacterial, and antioxidant activities. Secondary metabolite compounds, that is, jasmonic acid (JA) and methyl jasmonate (MeJA), significantly influence secondary metabolism regulation by stimulating the accumulation of phenols, flavonoids, and alkaloids.
Objective
The research aimed to estimate the effect of both JA and MeJA on growth parameters, chemical composition, particularly secondary metabolism, and the composition of volatile oils of L. angustifolia Mill plants.
Materials and methods
In the experiment, JA concentrations of 0, 1, 5, and 10 mM and MeJA concentrations of 0, 0.25, 0.50, and 1.0 mM were used as foliar spray applications on L. angustifolia. The investigation was performed as a randomized complete block design in three replicates. The parameters collected were different growth parameters, essential oil components using gas chromatography–mass spectrometry, the number of glands and secretory trichome diameter by scanning electron microscope, as well as chemical constituents.
Results and conclusion
The results showed that growth parameters were increased gradually with the increasing of JA and MeJA concentrations. The effects of JA and MeJA at high concentrations were more effective on all the growth parameters, biochemical components, and the number of glands and diameter of secretory trichomes than other concentrations and control plants in both seasons. JA application significantly increased chlorophyll a and b, carotenoids, and N and protein content of lavender plants. MeJA gave the highest values of total sugar, free amino acids, and phenols. Therefore, the results suggested that 10 mM of JA and 1.0 mM of MeJA significantly stimulate lavender plant growth and chemical compounds and volatile oil components, especially linalool and camphor, increasing its value and raising its quality in the perfume and cosmetics industries and various chemical industry applications.