In vitro mineral nutrition of Curcuma longa L. affects production of volatile compounds in rhizomes after transfer to the greenhouse
2018
El-Hawaz, Rabia F. | Grace, Mary H. | Janbey, Alan | Lila, Mary Ann | Adelberg, Jeffrey W.
BACKGROUND: Turmeric is a rich source of bioactive compounds useful in both medicine and cuisine. Mineral concentrations effects (PO₄³⁻, Ca²⁺, Mg²⁺, and KNO₃) were tested during in vitro rhizome development on the ex vitro content of volatile constituents in rhizomes after 6 months in the greenhouse. A response surface method (D-optimal criteria) was repeated in both high and low-input fertilizer treatments. Control plants were grown on Murashige and Skoog (MS) medium, acclimatized in the greenhouse and grown in the field. The volatile constituents were investigated by GC-MS. RESULTS: The total content of volatiles was affected by fertilizer treatments, and in vitro treatment with Ca²⁺ and KNO₃; but PO₄³⁻ and Mg²⁺ had no significant effect. The content was higher in the high-input fertilizer treatments (49.7 ± 9 mg/g DM) with 4 mM Ca²⁺, 60 mM KNO₃ and 5 mM NH₄⁺, than the low-input fertilizer (26.6 ± 9 mg/g DM), and the MS control (15.28 ± 2.7 mg/g DM; 3 mM Ca²⁺, 20 mM K⁺, 39 mM NO₃⁻, 20 mM NH₄⁺, 1.25 mM PO₄³⁻, and 1.5 mM Mg²⁺). The interaction of Ca²⁺ with KNO₃ affected curcumenol isomer I and II, germacrone, isocurcumenol, and β-elemenone content. Increasing in vitro phosphate concentration to 6.25 mM increased ex vitro neocurdione and methenolone contents. CONCLUSION: These results show that minerals in the in vitro bioreactor medium during rhizome development affected biosynthesis of turmeric volatile components after transfer to the greenhouse six months later. The multi-factor design identified 1) nutrient regulation of specific components within unique phytochemical profile for Curcuma longa L. clone 35–1 and 2) the varied phytochemical profiles were maintained with integrity during the greenhouse growth in high fertility conditions.
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