The effect of salt stress on germination, growth and concentration of glycyrrhizic acid in liquorice (Glycyrrhiza glabra)

The root of liquorice contains a large amount of glycyrrhizic acid which are known to have various food, industrial, cosmetic and pharmaceutical applications. Regarding to spreading of salinity in arid and semi-arid regions, to assay the tolerance levels of salinity in germination and vegetative stages and the effect of salt stress on the concentration of glycyrrhizic acid in liquorice plant, an experiment performed based on a randomized complete design with at least three replications. Salt stress applied at four levels including 0, 100, 200 and 300 mM NaCl. Our results at the germination stage showed that NaCl at 100 mM level caused a significant decrease in germination rate and percentage and the length of primary root and hypocotyl were diminished. While 200 and 300 mM levels of NaCl inhibited the germination. The results at vegetative stage showed that high salinity levels decrease the root/shoot dry weight ratio, plant yield, protein content and the K/Na, Ca/Na, Mg/Na ratios of shoot and root while the concentration of 300 mM NaCl caused a significant increase in root dry weight and shoot malondialdehyde and total phenol content in comparison with control. Also, the high concentrations of salinity increased the concentration of glycyrrhizic acid in roots. According to measured results at germination and vegetative stages of liquorice plant, it can be concluded that salt tolerance is a developmental stage specific phenomenon. Also, that cultivation of liquorice in saline soils potentially could increase glycyrrhizic acid accumulation in liquorice roots.