Matricaria is an important medicinal specie that is widely planted in salt-affected soils. The influence of salinity and drought tolerance on Matricaria has not been well documented in the literature. This investigation was undertaken to study the effects of NaCl and drought on germination and physiological, biochemical, and growth responses of two chamomile species. Seeds were germinated at five osmotic potential levels, 0, -0.175, -0.358,-0.541 and -0.716 MPa NaCl (equal to control, 5, 10, 15, and 20 dS/m ) for salinity and 0, -0.05, -0.1, -0.2 and -0.3 MPa polyethylene glycol (PEG6000) for drought. Then the growth of chamomile was studied at five salinity levels (0, 5, 10, 15 and 20 dS/m by NaCl in hydroponic solution media). In order to examine drought stress, gravitational method and four treatments (FC soil moisture content, and 75, 90 and 95 depletion percent of soil AWC) in a pot experiment were used. Shoot and root dry weight, shoot height , root depth , macro and micro element concentrations, NO 3 - , RWC, proline, flavonol-O-glycosides, chlorophyll a and b was determined. Seeds were not germinate at -0.8 MPa NaCl and -0.4 MPa of PEG. Germination reduction in solution of PEG was more significant than in NaCl. M. aurea and M. chamomilla were not grown at 20 and 25 dS/m NaCl, respectively. Plant growth significantly increased with increasing NaCl concentration up to 40 mM while decreased at higher salinity levels. The concentration of chloride and sodium ions was increased significantly in various parts of the plant with salinity .There were a decrease in K/Na and Ca/Na ratios in shoots and roots. Plants maintained considerably higher K/Na ratio in the shoots than those in the roots. Chamomile species are tolerant to moderately salt tolerant crop during growth. This might be associated with maintenance of high K/Na and Ca/Na ratios in shoots, accumulation of Na in roots, and proline accumulation in shoots This study showed that M chamomilla i more salt tolerant than M. aurea . The M. aurea species was more drought tolerant than M. chamomilla . Mineral nutrient concentrations decreased with drought severity. The Results showed that both salinity and drought reduced flower dry weight and flavonoids concentration, but the effect of drought was more pronounced 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.
