Influencia de dos tipos de fertilización sobre la flora adventicia, la producción y el contenido en flavonoides en un cultivo de Achillea millefolium L. en Galicia (NW de España)

In recent years, yarrow cultivation ( Achillea millefolium L.) has been increasing in several Europeancountries, in view of increasing demand from the herbal medicine and cosmetics industries. However, little is known about optimal cultivation practices for this crop, such as fertilization and weed control. Weed control is of particular interest, since buyers generally require the crop to be free of herbicide residues. In the present study we investigated the effects of fertilizer use (mineral fertilizer, organic fertilizer, or no fertilizer) on weed flora and the yield and flavonoid contents in a first-year yarrow crop in northwest Spain. Weeds were controlled by manual hoeing three times over the 10-month cultivation period. Our results indicate that neither mineral nor organic fertilization were beneficial: both types of fertilization increased weed cover and weed species diversity, and significantly reduced yarrow yield. In the non-fertilized plots, by contrast, weed cover was maintained at acceptable levels by the manual hoeing. Furthermore, fertilization did not appear to improve flavonoid contents, except for a small effect on apolar flavonoid contents in stems with mineral fertilization. These results suggest that fertilization is not beneficial for first-year yarrow crops in our region, though this conclusion may not be generalizable to other regions.In recent years, yarrow cultivation ( Achillea millefolium L.) has been increasing in several Europeancountries, in view of increasing demand from the herbal medicine and cosmetics industries. However, little is known about optimal cultivation practices for this crop, such as fertilization and weed control. Weed control is of particular interest, since buyers generally require the crop to be free of herbicide residues. In the present study we investigated the effects of fertilizer use (mineral fertilizer, organic fertilizer, or no fertilizer) on weed flora and the yield and flavonoid contents in a first-year yarrow crop in northwest Spain. Weeds were controlled by manual hoeing three times over the 10-month cultivation period. Our results indicate that neither mineral nor organic fertilization were beneficial: both types of fertilization increased weed cover and weed species diversity, and significantly reduced yarrow yield. In the non-fertilized plots, by contrast, weed cover was maintained at acceptable levels by the manual hoeing. Furthermore, fertilization did not appear to improve flavonoid contents, except for a small effect on apolar flavonoid contents in stems with mineral fertilization. These results suggest that fertilization is not beneficial for first-year yarrow crops in our region, though this conclusion may not be generalizable to other regions.