Polyphenolic Compound Variation in Globe Artichoke Cultivars as Affected by Fertilization and Biostimulants Application

Globe artichoke is an ancient herbaceous plant native to the Mediterranean Basin. Theedible part of the plant is limited to the fleshy leaves (bracts) and receptacle of a large immatureinflorescence (head) that has been shown to be a rich source of bioactive compounds. Nutritionaland pharmacological properties of artichoke heads and leaves are attributed mainly to polyphenoliccompounds and inulin present at high concentration. In this study, polyphenols were investigated intwo artichoke cultivars (Opal and Madrigal) in response to four nitrogen rates and foliar applicationsof biostimulating products under drip irrigation. Field experiments were carried out over twogrowing seasons (2015-2016, 2016-2017) in Policoro (MT), Southern Italy, on a deep clay soil insub-humid climate conditions. Phenolic compounds were isolated and characterized by meansof high-performance liquid chromatography with photodiode array detection and electrosprayionization/mass spectrometry (HPLC-DAD-MS/MS) analysis. In both cultivars, caffeoylquinic acidswere more abundant when a dose of 100 kg ha-1 of ammonium nitrate was provided, whereasapigenins were not affected by nitrogen fertilization. Luteolins increased in cv Opal and decreasedin cv Madrigal following N fertilization. The application of biostimulants (3 L ha-1) favored theaccumulation of polyphenols, in particular of caffeoylquinic acids and apigenin, in artichoke headsin both cultivars. The results obtained highlight some positive aspects related to the synergistic effectof nitrogen fertilization and biostimulant foliar application.