Abstract:
The environmental stress
such as, salinity (soil or water) and drought
are serious obstacles for medical plants and
field crops in further areas of the world,
especially arid and semiarid regions. In
order to investigate salinity and drought
stress on T. daenensis and T. kotschyanus
germination indices, an experiment was
carried out. To create salinity stress, sodium
chloride (NaCl) at the levels of 0 (as
control), -3, -6 and -9 bar, and for drought
stress, polyetylenglycol 6000 (PEG 6000) in
osmotic levels at 0 (as control), -3, -6 and -9
bar were used. Effect of drought and salt
levels on investigated traits significant at
0.01. Result showed significance different
between evaluated indices. Increasing of
stress levels lead to reduction of
germination and root and shoot length. Salt
stress only in high levels reduced
germination rate. Therefore, T. daenensis
and T. kotschyanus have relative resistance
to salinity in germination stage. Decrease in
osmotic potential progressively inhibited
seed germination of the two thyme species.
In all salt treatments, maximum germination
percentage in T. kotschyanus related to West
Azerbaijan population and maximum
germination rate related to Gazvin
population. But in T. daenensis the highest
values (both rate and percentage
germination) were observed in Arak
population. The germination rate of T.
daenensis to the drought stress was more
than the T. kotschyanus germination rate
like the germination percentage. Comparing
the two stresses, it appears that drought has
more effect than salt in germination indices.
