Abstract
The present study was performed to investigate the effects of different light periods including 8, 16 and 24 h d−1 light in combination with two levels of light intensity, 100 and 200 μmol m−2 s−1 besides daily light integral (DLI; the product of light intensity and light period) on the growth and essential oil composition of Japanese mint plants (Mentha arvensis L. var. piperascens), a traditional aromatic and medicinal plant. The results revealed that growth was greatest in plants grown at 24 h d−1 light period combined with 200 μmol m−2 s−1 of photosynthetic photon flux (PPF). There was no menthofuran detected in plants under either of the applied treatments. The l-menthone and l-menthol concentrations were highest in plants treated by 16 h d−1 light period combined with 200 μmol m−2 s−1 PPF. The highest content of these compounds was produced by plants grown under DLI of 8.64 mol m−2 d−1 and more. Results revealed that light period exerts the most important effect on altering the growth and essential oil production of Japanese mint compared to light intensity and DLI.
