فهرست مطالب رقیه نظریان سیرزار

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.

Salinity is a major environmental factor limiting plant growth in natural ecosystems. Glycyrrhiza glabra is an important Fabaceae (perennial plant) that its root and rhizome extracts are used in food, health, medical and pharmaceutical industries. To assess the effect of methyl jasmonate (MeJA) and salinity on licorice, an experiment was conducted as factorial based on completely randomized design with three replications. Accordingly, plants were exposed to the concentrations of 0, 100, 200 and 300 mM NaCl for five weeks, 24 h after foliar application of 0, 50 and 100 µM MeJA. In our experimental condition, a significant decrease in shoot dry weight, shoot and root fresh weights, plant height, leaf relative water content (RWC), Ca concentration of shoot and root and root Mg concentration were observed at 300 mM NaCl, while total chlorophyll, chl a and chl b concentrations and carotenoids were not affected significantly by salinity. Also, NaCl at 300 mM caused a significant increase in proline and total soluble sugar contents, Na+/K+ ratio and dry weight of roots. Results showed that exogenous application of MeJA at 50 µM level improved plant tolerance to salinity up to 200 mM NaCl and increased growth parameters, photosynthetic pigments, soluble sugar and proline content of shoot and root in comparison with control. Moreover, the application of MeJA caused a significant increase in Mg concentration of the shoot and root of control plants.