Morphological and biochemical changes during growth and development of artichoke buds

In two artichoke cultivars, 'Violetto di Provenza' ('VP') and 'Terom' ('T'), changes in some morphological and biochemical parameters during bud development were studied. Artichokes were field grown in Margherita di Savoia (Foggia province, Southern Italy). For 'VP', owing its large calendar of production (from October to May), two periods of harvesting (winter and spring) were investigated, while for 'T' only the spring harvesting was considered. Starting from buds of about 60 g, seven pickings were performed at 6 or 4 day intervals for winter and spring harvest, respectively. Morphological parameters as average weight, bud diameter, length of inflorescence (pappus) and percentage of inner violet bracts were evaluated. In all physiological stages, phenolic and sugar content of hearts were determined by HPLC. Amongst phenolics, chlorogenic acid, dicaffeoylquinic acids and the flavonoid apigenin-7-glucoside were detected. Glucose, fructose, sucrose and inulin content were also ascertained. Chlorogenic and dicaffcoylquinic acid content decreased during the bud growth, more markedly in the spring harvesting for 'VP', while apigenin-7-glucoside remained almost constant. Amongst sugars, glucose and sucrose showed an increasing trend, whereas fructose maintained the initial low values. In 'VP' the inulin content increased from 3000 to 8000 and from 3000 to 5700 mg 100g(-1) f.w. in the winter and spring harvesting, respectively while in 'T' it ranged from 2000 mg 100g(-1) f.w. in the youngest to 3000 mg 100g(-1)f.w. in the oldest physiological stage.