Plants of Achillea millefolium L. grown under colored shading nets have altered secondary metabolism

Resumo

Here we evaluate the effect of quality and quantity of light on growth and secondary metabolism of Achillea millefolium L. plants. Plants were cultivated under either full light or colored shading nets (blue, red or black). Analyzes were performed after eight weeks of shading and two and four weeks after the removal of the nets. Plants grown under nets presented lower dry weight of leaves and flowers. In addition, the synthesis of phenols and flavonoids decreased in leaves and flowers of shaded plants. On the other hand, the blue net increased the content of essential oil yield in leaves. The concentration of the majority of the compounds analyzed in the essential oil increased when using the black net. Farnesol and chamazulene were the most plenteous compounds in the oil of leaves and flowers in all conditions. Overall, these results indicate that different compounds respond differently to specific light lengths in A. millefolium plants. Thus, the photoselective treatments should be directed to the production of the target metabolite.