The Content of Biologically Active Substances in <i>Crocosmia</i> × <i>crocosmiiflora</i> ‘Lucifer’ Tubers after Treatment with GA₃

This study was conducted to assess the influence of gibberellic acid (GA₃) on the content of biologically active substances in <i>Crocosmia</i> × <i>crocosmiiflora</i> ‘Lucifer’ tubers. These tubers are a promising source of potential antioxidants, and their extracts can be used in pharmaceutical industry, as well as in cosmetics products and antifungal and antibacterial substances. Four groups of biologically active substances were determined from tubers: saponins, phenolic acid, flavonoids and carotenoids. The antioxidant activity of the extracts from tubers increased proportionally to the GA₃ concentrations. GA₃ at concentrations of 200, 400 and 600 mg dm⁻³ increased the content of medicagenic acid by 42.9–57.1% and the content of polygalic acid by 50% without affecting the content of medicagenic acid 3-<i>O</i>-triglucoside. The GA₃ concentrations used in the experiment positively influenced the accumulation of caffeic acid, <i>p</i>-coumaric acid and gallic acid. The highest content of caffeic acid was noted in the tubers soaked in GA₃ concentrated at 400 and 600 mg dm⁻³. GA₃ at a concentration used in the study stimulated the accumulation of kaempferol by 15%, quercetin by 7–8.2%, quercetin 3-<i>O</i>-glucoside by 1.8% (when GA₃ was applied at a concentration of 200 mg·dm⁻³) and by 4.1% and 3.6% (when GA₃ was applied at concentrations of 400 and 600 mg·dm⁻³) and kaempferol 3-<i>O</i>-rhamnosylglucoside by 1.5–3.4%. The soaking of the tubers in GA₃ increased the content of β-carotene by 7.9%, 5.2% and 7.9%, respectively, without affecting the content of crocin. For soaking of <i>Crocosmia</i> tubers, it is recommended to use GA₃ at a concentration of 400–600 mg·dm⁻³.