In vitro mineral nutrition of \u3ci\u3eCurcuma longa\u3c/i\u3e L. affects production of volatile compounds in rhizomes after transfer to the greenhouse

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 KNO3affected 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

Maximum growth responses for multiplication, fresh biomass and rhizome dry mass were observed in different fed-batch techniques, mineral concentrations and plant densities.

<p>Minerals concentration in milimolar. NSF stands for Nutrients Sucrose Fed-batch; SF stands for Sucrose Fed-batch.</p><p>Maximum growth responses for multiplication, fresh biomass and rhizome dry mass were observed in different fed-batch techniques, mineral concentrations and plant densities.</p

The interaction of plant density and mineral concentrations affected turmeric multiplication ratio.

<p>The response surface plots (with residual data points) shows multiplication ratio of <i>Curcuma longa</i> L. as effected by the interaction of initial plant density (buds/vessel) × Ca concnentraion when other factors were fixed in the nutrient sucrose fed-batch technique, with 6.25 mM P and (a) 20 mM KNO₃ and (b) 60 mM KNO₃.</p

Sucrose supplemented (g/vessel) to maintain growth over 22 weeks in treatment conditions.

<p>The response surface plot (with residual data points) shows the effect of P × KNO₃ on the amount of sucrose (g/vessel) required to restore sucrose set point 5% m/v. Other factors were fixed in the nutrient sucrose fed-batch technique, 3 mM Ca, 3.56 mM Mg, and 18 buds/vessel.</p

Water supplemented (ml/vessel) to maintain growth over 22 weeks in treatment condition.

<p>The response surface plot (with residual data points) shows the effect of P × KNO₃ on the amount of water (ml/vessel) required to restore medium volume set point of 200 ml per vessel. Other factors were fixed in the sucrose fed-batch technique, with 3 mM Ca, 1.5 mM Mg, and 18 buds/vessel.</p

Additional file 1: of In vitro mineral nutrition of Curcuma longa L. affects production of volatile compounds in rhizomes after transfer to the greenhouse

Turmeric volatile constituents data. (XLSX 26 kb

Turmeric multiplication ratio over 22 weeks in treatment conditions.

<p>The response surface plot (with residual data points) shows multiplication ratio of <i>Curcuma longa</i> L. as effected by the initial plant density (buds/vessel) and P concentration. Other factors were fixed in the nutrient sucrose fed-batch technique, with 3 mM Ca, and 20 mM KNO₃.</p

Turmeric fresh biomass (g/vessel) over 22 weeks in treatment conditions.

<p>The response surface plot (plus residual data points) shows <i>Curcuma longa</i> L. fresh biomass (g/vessel) was affected by P × KNO₃ interaction. Other factors in the nutrient sucrose fed-batch technique were fixed with 18 buds/vessel, 3 mM Ca, and 3 mM Mg.</p

Turmeric rhizome dry biomass (g/vessel) over 22 weeks in treatment conditions.

<p>The response surface plot (with residual data points) shows rhizome dry biomass of <i>Curcuma longa</i> L. was affected by plant density (buds/vessel) and P concentration. Other factors are fixed in the sucrose fed-batch technique, with 9 mM Ca, 4.5 mM Mg, and 36 mM KNO₃.</p