The influence of NaCl-induced stress on the growth and volatile profile of Curcuma longa L. leaves
Herein, for the first time, the influence of salt-induced stress on the vegetative growth and the volatile profile of Curcuma longa L. leaves was investigated. C. longa was grown in a quarter-strength Hoagland?s solution to which NaCl was added to give four final concentrations: 0 (control), 25, 50 or 75 mM NaCl. In the case of the plants grown in the 25 mM NaCl medium, leaf biomass production was the same as in the control experiment, but it decreased significantly at higher salinities (50 mM and 75 mM NaCl). The volatile constituents of the leaves were isolated by hydrodistillation and analyzed by GC and GC/MS. The essential-oil yield (calculated on the basis of dry weight) was 2.0% for the control plants, and increased at low-to-medium NaCl concentrations (2.5% and 2.8% for the 25 and 50 mM NaCl media, respectively). Contrary to that, the essential-oil yield decreased (1.6%) in the case of plants grown in the 75 mM NaCl medium. The major volatile constituents of C. longa leaves were identified as: ?-phellandrene (38.3-42.4%; more than one third of the total oil), terpinene-4-ol (5.6-10.5%), geraniol (5.6-7.9%), p-cymene (5.2-9.6%), ?-thujene (4.5-7.3%), ?-sesquiphellandrene (4.8-6.8%), ?-myrcene (2.6-3.8%) and ?-bisabolol (1.5-2.7%).