Weed composition in conventionally and organically grown medical and aromatic plants

This study aimed to compare weed flora in conventionally and organically grown medicinal and aromatic plants (MAPs): basil, pot marigold, dill, and peppermint; in terms of weed composition and weed abundance. A total of 28 weed species (25 and 15 species in conventional and organic crops, respectively) were identified.The presence and abundance of certain weed species were affected by MAP species and farming system. Higher weed diversity and weediness, and lower floristic similarity were found in conventionally grown crops. Also, the analysed MAPs differed in weediness by individual weed species. Correspondence analysis pointed to conventional and organic MAPs with the most frequent and most abundant weed species. Setaria pumila and Portulaca oleracea were the most frequent species in conventional; and Amaranthus retroflexus, Datura stramonium, and Sorghum halepense in organic crops. In both conventional and organic farming systems, therophytes were the most dominant life forms indicating a strong anthropogenic influence. The results should contribute to establishing weed control measures that are adequate for the two farming systems.