Light and natural ventilation systems optimize the growth and production of volatile compounds in micropropagated Mentha piperita L. plantlets

Abstract

Mentha piperita L. is a medicinal, aromatic, and flavoring species whose essential oil is rich in volatile compounds, including menthol, menthofuran, pulegone, and menthone. The aim of the present study was to assess the effect of light intensity, different wavelengths, and natural ventilation on the development and production of volatile compounds. Nodal segments were cultured in MS medium under the following photon flux densities: 20, 57, 78, 102, and 139 μmol m −2 s −1 , and white, blue, and red wavelengths (50%R/50%B, 30%R/70%B, and 70%R/30%B). In addition, nodal segments with one pair of leaves were cultured in MS medium in vials with one (NVS1), two (NVS2), or four (NVS4) porous membranes. Growth, leaf, stem, root, total dry weight, photosynthetic pigments, and volatile chemical composition were assessed 30 d later. Plantlets grown under 20 μmol m −2 s −1 were etiolated, and they accumulated higher photosynthetic pigments, α-pinene, β-pinene, and menthol levels. The following light intensities enhanced leaf and total dry weight production: 78, 102, and 139 μmol m −2 s −1 . Light intensity did not affect menthofuran and pulegone levels. White and blue light (50%R/50%B, and 30%R/70%B) enhanced leaf and root dry weight accumulation. Red light (50%R/50%B and 70%R/30%B) increased menthofuran production. Plantlets showed longer shoot length and higher leaf, stem, and root dry weight when they were grown in NVS4 in vitro . Porous membranes triggered menthofuran productionin culture systems in vitro under different light intensities and qualities.

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