Exogenous salicylic acid modifies gas exchange and biomass production of Mentha x piperita L.

Peppermint (Mentha × piperita L.) is a medicinal plant that produces an essential oil used as an additive in food and pharmaceutical formulations. Salicylic acid is a phenolic compound widely distributed throughout the plant kingdom, being able to modify plant physiological and metabolic responses. The objective of this study was to evaluate the effects of the application of salicylic acid on the production of biomass, pigments, as well as gas exchange of peppermint plants. For this purpose, a completely randomized design composed of four replications was applied. Pigment evaluations were carried out in a 4×4 factorial scheme, consisting of the application treatments: 0 (control), 75, 150, and 225 mg L-1 of salicylic acid and four harvest periods. Gas exchange and physiological growth rates were evaluated in a 4×3 factorial scheme. Data were submitted to analysis of variance and regression. The application of salicylic acid increased CO2 assimilation and use, stomatal conductance, water use efficiency, and transpiration, which in turn, resulted in increased height, and dry stem and root mass production. It is concluded that the application of salicylic acid influences the primary metabolism, increasing gas exchange and biomass production of peppermint plants.