YIELD AND HARVEST TIME OF GLOBE ARTICHOKE IN RELATION TO NITROGEN AND PHOSPHORUS FERTILIZATION

Few and insufficient attempts have been made until now to study globe artichoke crop response to nitrogen and phosphorus fertilization. In particular, to our knowledge no information is available for recently developed seed-grown cultivars. The aim of this paper was to study the effects of nitrogen and phosphorus fertilization on yield and harvest time of globe artichoke in order to evaluate the possibility of its rationalizing and improvement. Field experiments were conducted in two growing seasons at Siracusa - south Italy (36°58’ N, 15°11’ E, 15 m a.s.l.). The following experimental treatments were compared: a) two P₂O₅ fertilization rates, 50 and 200 kg P₂O₅ ha^-1; b) four N fertilization rates, 0, 150, 300 and 450 kg N ha^-1; two cultivars ‘Violetto di Sicilia’, vegetatively propagated, and ‘Orlando F1’, seed propagated. The results of this study showed that yield significantly increased with increasing nitrogen rate from 0 to 300 kg ha^-1 and did not vary with 450 kg N ha^-1. The results suggest that optimum nitrogen application rate was 300 kg ha^-1 and that 200 kg P₂O₅ ha^-1 improved the yield response of globe artichoke to nitrogen fertilization. The yield response to phosphorus varied with cultivars. In fact, irrespective of nitrogen rate, head yield of ‘Violetto di Sicilia’ was improved by 200 kg P₂O₅ ha^-1, while yield of ‘Orlando F₁’ was improved by 50 kg P₂O₅ ha^-1.