Foliar application of gibberellic acid improves yield and head phenolic compounds in globe artichoke

Abstract

Applications of gibberellic acid (GA3) during the vegetative stage is used routinely in artichoke production systems in semi-arid regions to induce vernalization and improve yield. The objective of this two-year field study was to evaluate the effect of exogenous GA3 (20 mg l−1) application date (4th and 8th leaf stages) and frequency (two and three times) on morphological and physiological traits, yield and head quality of globe artichoke (Cynara cardunculus L. cv. Green Globe Improved) under a warm and semi-arid environment. Foliar application of GA3 at the 4-leaf stage increased plant height across growing seasons. However, no significant differences between application dates were noticed in plant width, gas exchange and leaf area index when measured at the harvesting period. GA3 application frequency (two or three) did not affect yield and head quality. Interestingly, foliar application of GA3 at 8-leaf stage increased yield by 13%, chlorogenic acid by 19%, cynarin by 30% and total N by 20% compared to the application at 4-leaf stage. In both years, GA3 applied at 8-leaf stage delayed the harvesting by 10 days when compared to plants that received GA3 application at 4-leaf stage. Considering the increase in yield and head quality without negative effects in canopy morphology or leaf physiology two applications of GA3 at the 8-leaf stage appears an effective crop management strategy for globe artichoke grown under warm climates.