Compostos elicitores em alecrim: efeitos sobre a produção de biomassa, atividade antioxidante e síntese de óleo essencial e ácido carnósico

Abstract

Rosemary (Salvia rosmarinus Spenn.) is a medicinal plant with wide use in the pharmacological, cosmetic and food industries. Elicitor substances in plants are compounds that stimulate the production of bioactive metabolites and can additionally stimulate growth. The objective of this study was to evaluate the effect of foliar application of the elicitors salicylic acid (SA) and seaweed extract (SE) on rosemary. The experiment was conducted in a greenhouse, with a completely randomized design, consisting of five treatments [T1 = control, T2 = SA 1.0 mmol L-1, T3 = SA 2.0 mmol L-1, T4 = SE (Ascophyllum nodosum – 6 mL L-1) and T5 = SE (Solieria chordalis – 2 mL L-1)] and 10 replications. Responses to elicitation were evaluated using biometric parameters (plant height, number of branches, fresh mass and dry mass of shoots) and biochemical parameters (total carbohydrates, total phenolic compounds and antioxidant activity via DPPH). The concentration and yield of essential oil (EO) were determined, with identification of the compounds present in it; as well as foliar concentrations of antioxidants (carnosic acids and carnosol). There was no difference between treatments on biomass growth, with the exception of the number of branches, which was lower in plants treated with 1.0 mM AS and S. chordalis. The concentration of total polyphenols and antioxidant activity by DPPH did not change in relation to the control. Treatments with AS 1mM and S. chordalis resulted in increases of 46.04% and 35.7%, under OE respectively. The majority components in the OE were not changed by elicitation. Regarding the concentration of carnosic acid, there was an increase of 49.87% within 24 hours after application of plants treated with 2.0mM SA. 48 hours after the last application of the elicitors, there was no difference between the treatments. The carnosol concentration increased by 28.1% in plants treated with A. nodosum (24 hours after application of the elicitors), and by 27.2% and 23.85% in plants treated with A. nodosum and S. chordalis (48 hours after application of the elicitors). These results indicate that the elicitation of S. rosmarinus plants with AS and SE did not change the fresh and dry mass of the plants, promoted significant increases in essential oil biosynthesis and stimulated the oxidation of carnosic acid to its derivative, carnosol.