Effects of gibberellic acid and sowing date on harvest time and yields of seed-grown globe artichoke (Cynara scolymus L.)

A 2 year research project was carried out in Sicily (south Italy), in order to study tlie effects of gibberellic acid (GA3) (0, 1, 2 or 3 plant applications at 60 ppm) and sowing date (from 1 July to 10 August) on the timing of production and head yield of globe artichoke variety Orlando, a new seed-grown hybrid. Regardiess of sowing date, untreated plants of Orlando produced heads the next spring, confirming that in the Mediterranean environment seed-grown varieties bave to overcome the winter season or part of it to meet their cold requirement for flower initiation. GA3 application replaced this cold requirement, allowing autumnal production. GA3 effectiveness, however, was more evident in early sowings than in later ones. In fact, a combination of early sowings (1 and 10 July) and GA3 application (2 or 3 times) resulted in a pattern of head production of Orlando similar to that of Violetto di Sicilia (VS), a typical early vegetatively propagated variety. In addition, the total cumulative yield at the end of cycle was significantly higher in Orlando than in VS.