Harvest Frequency Affects Leaf Yield and Polyphenols in Artichoke (Cynara cardunculus L.).

Artichoke is a traditional vegetable crop of south European countries and is best suited to semiarid environment. Leaves of artichoke contain high percentage of polyphenols which are considered choleretic, antioxidative, hepatoprotective, and cholesterol reducing. Harvest frequency may influence leaf yield and polyphenols of artichoke.

Present research study was conducted to study the influence of harvest frequency on leaf yield and polyphenols of artichoke. Three harvest frequencies i.e. low (3 cuts), medium (5 cuts) and high (6 cuts) were randomized in quadruplicated RCBD. Data were collected using standard procedures and polyphenols were identified and quantified by HPLC (Brand and Weschta, 1991).

The lowest harvest frequency (LHF) led to highest dry matter yield of 11.05 t ha^-1 in 2006 and 6.89 t ha^-1 in 2007, which was statistically higher than that of other harvest frequencies during both years. The concentration of polyphenols in the leaves of artichoke differed for both the experimental years i.e. higher concentration of polyphenols (CQAs: 2.95 % DM and flavonoids: 1.12 % DM) was recorded in 2007 as compared to that of 2006 (CQAs: 1.17 % DM and flavonoids: 0.55 % DM).  The lowest number of harvests (LHF) led to the highest concentration of polyphenols in the leaves during both experimental years when compared with that of other harvest frequencies. Higher dry matter yield and concentration of polyphenols obtained in the low harvest frequency might be a result of the longer vegetative growth period of the crop. It is supposed that more UV light was intercepted by artichoke leaves, which induced photosynthetic activity and more photosynthates were produced and resulted in higher leaf yield as well as higher concentration of polyphenols.