Higher yields and improvement of the quality of products is also attributable to an appropriate contribution of nutriments. Marketable yield, yield components, quality and phenolic compounds of globe artichoke (‘Opal’ and ‘Madrigal’) heads were investigated in response to four nitrogen rates (0 to 50, 100, and 150 kg/ha) in combination with two foliar applications of biostimulating products (0 to 3 L/ha). Field experiments were conducted over two seasons (2009-2010 and 2010-2011) at the experimental station of the CNR-Institute of Plant Genetics, in Policoro (MT), southern Italy, on a deep clay soil in sub-humid climate conditions. Yields and head weight significantly increased with nitrogen rate, whereas no significant effect was recorded by the use of biostimulating products. Regardless of the cultivar, the highest caffeoylquinic acid and luteolin content occurred at a dose of 100 kg/ha of N, while the total apigenin seems to be more synthesized in the absence of fertilization. The application of biostimulating products favoured the accumulation of polyphenols in artichoke heads. Based on these results, we estimated the nitrogen rate and biostimulating nutrition to obtain high marketable yields, superior size and nutritional head quality of artichokes in southern Italy.
