Effect of environment and gibberellic acid (GA3) on earliness and yield of globe artichokes

Artichoke production in Croatia is concentrated on islands and in coastal area with main harvest in spring time. The aim of this paper was to research the influence of different concentrations of gibberellic acid (GA(3)) on earliness and yield of cv. Imperial Star. Research was conducted during two years on island (Jelsa, 42degrees59'N, 16degrees41'E) and in the coastal area (Opuzen, 42degrees50'N, 17degrees33'E). In both years planting was done on 28 September in Jelsa and 20 September in Opuzen. GA(3) in concentration of 0, 12.5, 25, 50, 75 and 100 ppm was applied on plants with 12 developed leaves. Growth of the head stalk, early and the total yields, and average head weight were evaluated during experiment. An elongation of head stalk was influenced by GA3 application on both locations and in both years. The highest stalks were recorded with application of 75 ppm GA(3). Harvest beginning was most influenced by year and location of growing, even though greatest early yield was achieved with 50 ppm GA(3). The total yield and average head weight varied depending on location and year of growth, but they were not affected by GA(3). Although the influence of GA(3) on growth and early yield was noticed, the effect depends on the climatic conditions after treatment and during growth period.