Abstract

The aim of the study was to evaluate the effect of the arbuscular mycorrhizal fungi (AMF), Acaulospora morrowiae, Rhizophagus clarus and Scutellospora calospora on the growth and essential oil production of Mentha × piperita L. var. citrata plants. The experiment was conducted in a greenhouse with a 5 × 2 factorial design with five mycorrhizal treatments (uninoculated control, Acaulospora morrowiae, Rhizophagus clarus and Scutellospora calospora, and mixture of inocula) and two P levels (60 and 120 mg P dm^-3 soil) with six replicates. Plants were harvested after 75 days of growth for evaluation of dry biomass, mycorrhizal colonization of roots, number of spores in soil, nutrient content of leaves, and composition, content and yield of essential oil. The mycorrhizal treatments influenced all the characteristics evaluated, except the number of spores in soil. AMF colonization was most evident at the lowest dose of phosphate fertilizer applied, except for R. clarus, and in all treatments mycorrhizal colonization was above 45%. Colonization also influenced the nutrient content of the leaves of M. piperita var citrata and increased leaf dry biomass. The content and yield of essential oils were higher in plants colonized by AMF fungi with the 60 mg P fertilization dose, except those colonized by R. clarus which had higher essential oil production only with the 120 mg dm^-3 P treatment. The two major components in the essential oils for the plants in all the treatments were linalool and linalyl acetate.

Key words: Acaulospora, Rhizophagus, Scutellospora, linalool, linalyl acetate, phosphorus fertilization.