Effects of post-emergence weedicides on yield, polyphenolic acids, flavonoids and antioxidant potential of artichoke leaves

Artichoke is well known for its various medicinal properties i.e., lipid-lowering and antioxidant activity. Antioxidant activity of artichoke is mainly caused by the presence of various biologically active compounds, especially polyphenols. These polyphenols are being affected by a variety of environmental and cultivation factors including the application weedicides. The current study was aimed at clarifying the effects of various commonly used post-emergence weedicides (Phenmedipham, Pyridate, Quizalofop-p-ethyl, Prosulfocarb, Carfentrazone-ethyl, Rimsulfuron, Aclonifen, and Clomazone) on the production of polyphenolic compounds, including the flavonoids and caffeoylquinic acids. Weedicides were applied during the cultivation of artichoke in two growth phases. Polyphenols were analyzed in leaf extracts of artichoke using the HPLC method. In addition, the antioxidant activity of the leaf samples was determined. Results revealed minimum production of dry matter in the treatment with aclonifen (2.61 t ha-1). While different weedicide showed variable effects after each week (1st, 2nd, 3rd, 4th) of application. Significant difference among the various treatments of weedicide during both growth phases i.e., concentration of polyphenolics is being remarkably affecting by treatments with various weedicide. A positive correlation CQA (caffeoylquinic acid) with flavonoids on one hand and with ORAC (Oxygen Radical Absorbance Capacity) on the other showed the synergism among these. Moreover, the antioxidant capacity of artichoke leaf extracts is influenced by the content of caffeoylquinic acids and flavonoid in addition to some other antioxidants (carotenoids, terpenoids etc.). Weedicide application can lead to a reduction in phenolic constituents of artichoke leaf samples; however, this negative impact is quickly compensated during further growth and development of plant under moderate climate conditions.