Mentha spicata L. grown with nitrate: Ammonium proportions in different light environments

Mentha spicata L. is an aromatic and medicinal plant, known as mint and used in the pharmaceutical and cosmetic industry and in phytotherapy. Although the cultivation of medicinal plants is traditional, there are several questions about which practices are most appropriate in the management of these plants, especially regarding nutrition and availability of light. The objective of this work was to evaluate the growth, phytomass production and physiological aspects of M. spicata cultivated in proportions of nitrate (NO3-) and ammonium (NH4+) and light environments. The research was carried out in a greenhouse at the Universidade Federal do Reconcavo da Bahia, Cruz das Almas, BA, Brazil. The experimental design used was completely randomized, in a 5 x 3 factorial scheme, with five proportions of NO3-:NH4+ (0: 100; 25:75; 50:50; 75:25; 100: 0) and three light environments (ChromatiNet (R) meshes red, black and in full sun), with seven repetitions. There was a significant interaction between the proportions of ammonium and nitrate with the light environments for most of the evaluated parameters. It is concluded that M. spicata plants grown under balanced proportions of nitrate and ammonium in a light environment favorably favored the initial growth and physiological indications of this species.