THE EFFECTS OF SOME ENVIRONMENTAL STRESSES ON THE STIMULATION OF GERMINATION OF HYSSOP (HYSSOPUS OFFICINALIS)

Hyssop, one of the most important medicinal plants, is a perennial woody plant which belongs to the family Lamiaceae. To determine the effects of salinity and drought stress on its germination, two separate experiments were conducted using 4 levels of salinity and 4 levels of water stress (drought), induced by NaCl and polyethylene glycol (PEG 6000) respectively. Salinity caused a significant (P<0.01) reduction in rate of germination and radicle length 10 d after sowing, but not in germination percentage. The rate of germination increased up to -0.3 MPa and then decreased. The rate and percentage of germination and length of radicles were also significantly different in response to drought levels. This study indicated that salinity stress induced between -0.3 and -0.6 MPa could stimulate germination and hence, perhaps, improve seedling establishment.