Salinity and drought stress effects on flower yield and Flavonol-O- glycosides in Chamomile (Matricaria chamomilla L.)

Flavonoids are polyphenolic compounds with strong antioxidant effects. Chamomile (Matricaria chamomilla L.) is used for a variety of herbal remedies, containing classes of biologically active compounds including flavonoids and essential oil. There have also been many reports, showing that flavonol-O-glycosides are quantitatively the most abundant flavonoids found in chamomile flowers. Tolerance of this plant on saline and drought conditions has not been well studied and documented. Therefore a greenhouse experiment was conducted using complete randomized design with four replications in order to evaluate the effects of salinity and drought stress on flower dry weight and falavonoids component of chamomile. Hydroponic solutions are used for salinity experiment at five levels of NaCl concentrations (0, 40, 80, 120, 190 mM). In order to examine drought stress, we used gravitational method and four treatments (FC soil moisture content, and 75, 90, 95 depletion percent of soil AWC) in a pot experiment. Then the flower dry weight and their flavonol-O-glycosides were measured. The Results showed that both salinity and drought reduced flower dry weight and flavonoids concentration, but drought reduction effects were more than salinity. Flowers dry weight significantly increased with increasing NaCl concentration up to 40 mM while decreased at higher salinity levels. There were no significant differences between salinity treatments up to 80 mM NaCl for flavonol-O-glycosides concentration. Regarding the dry flower yield, the highest content of flavonol-O-glycosides was observed in 40 mM NaCl treatments. Flower dry weight and Flavonol- O- glycosides decreased as drought levels increased.