2018 ASHS Annual Conference

Globe artichoke (Cynara cardunculus var. scolymus) is emerging as a new specialty crop in Florida because of its high potential production value. However, suitable cultivars and production guidelines have not been established. Two field experiments were conducted under a subtropical climate in West Central Florida. To overcome chilling requirements of artichoke, plants were treated with gibberellic acid at 49 g·ha^–1 three times during the vegetative growth stage. First, we evaluated six cultivars and identified that marketable yield was highest in the order: ‘Imperial Star’ (7.25 t·ha^–1) > ‘Opal’ (4.30 t·ha^–1) > ‘Green Globe’ (3.85 t·ha^–1) > ‘Colorado Red Star’ (0.99 t·ha^–1) > ‘Purple Romagna’ (0.64 t·ha^–1) > Madrigal’ (0 t·ha^–1). Marketable yield of ‘Imperial Star’ was significantly higher than that of three lowest-yielding cultivars. The yield variation was due mainly to bud number per plant, with ‘Imperial Star’ producing the highest number of buds (3.9/plant) among all cultivars. Using ‘Imperial Star’, factorial combinations of five nitrogen (N) fertilization rates (106, 157, 206, 257, and 307 kg·ha^–1) and three in-row plant distances (76, 91, and 107 cm) were tested. Overall, N rates had stronger significant effects than plant spacing. For all in-row plant distances, plant width and leaf N concentration increased linearly with N rates. Marketable yield also increased linearly with N rates (1.73 to 5.13 t·ha^–1), averaging across in-row plant distances. Although area-based yield was unaffected by plant spacing, yield on a plant basis increased with increasing plant spacing. In addition, the linear trends of measured variables became generally stronger with increasing plant spacing, indicating more intense plant competition at narrow plant spacing. In the two trials, seedlings were transplanted on Oct. 2 to 16, 2017, and harvests were performed 8 to 12 times between Jan. 31 and Mar. 22, 2018, when market prices of artichoke are generally highest because of the low domestic supply. These results suggest that ‘Imperial Star’ is the most suitable cultivar to the subtropical growing conditions of Florida. Marketable yield of this cultivar can be maximized by adopting high N fertilization rates. Importantly, the enhanced earliness may support viable artichoke production in Florida.