Effect of Salinity and Drought Stresses on Seed Germination of Thymus satureioides

Abstract

Salinity stress and drought stress are the major environmental constraint for promoting medicinal plants in the arid lands of Morocco. To extendthe cultivation of Thymus satureioides in Tafilalet zone, Morocco, we investigate (in 2020) the effects of salinity and drought stresses on seed germination traits of T. satureioides. Salinity treatments included six concentrations of NaCl (0, 1, 2.5, 5, 7 and 10 g/l) and drought stress; five osmotic potentials of PolyEtylenGlycol 4000 (0, -0.1, -0.3, -0.6 and -0.9 MPa). Results showed that T. Satureioides tolerated salinity till the concentration of 2.5g/l of NaCl, which was statistically not different from control. Then, a highly significant reduction in germination percentage was recorded with the increasing salt concentration, only 38% seed germination was recorded for 5 g/l and a complete inhibition was started from 7 g/l and 10 g/l of NaCl. Decreasing osmotic potentials inhibited progressively and significantly seed germination, the germination percentage for -0.1 MPa, -0.3 MPa, and -0.6 MPa were 85.3%, 65.3%, 6.6% respectively. The two stresses (Drought and salinity) had negative impacts on seed germination, but the drought effect was accentuated than salinity in reducing germination.