A laboratory experiment was conducted during 2002-003. The purpose was
to develop an effective and rapid screening tool to assess the genetic variability
for the response of some local barley varieties to polyethylene glycol- induced
osmotic stres
s at early growth stage. Also this will help to evaluate the relevance
of pre-exposure of barley seedlings to sub-lethal (induction) levels of osmotic
stress. This might enhance the capacity of seedlings to tolerate the lethal levels
of stress.
A hydroponic culture experiment was conducted under the green house
conditions, at the general commission of scientific agricultural research, and
the faculty of agriculture, Damascus university, during the year 2002-003.
The objectives of this in
vestigation concentrated on the influence of four
salinity levels (0-50-100-150 mM NaCl) on some physiological parameters of
eight sorghum genotypes. The experiment was designed in a RCB design with
three replications.
Different experiments were conducted under laboratory conditions, at the
Faculty of Agriculture – Damascus University, in order to develop a suitable
and efficient screening tool, which can be applied to assess the genetic
variability among 20 sor
ghum genotypes (Izraa series) for high salt stress
tolerance.
We were able to develop a screening technique involves pre- exposing
sorghum seedlings to a sub – lethal level of salinity stress (induction stress) (150
mM NaCl) for 16 hrs which can induce the genotypes to prepare defensive
means, which may differ according to the genetic potentiality of each genotype.
These protective responses may help the genotype to endure the lethal level of
salinity stress (400 mM NaCl) for 48 hrs. At a later stage, the seedlings were
transferred to distilled water for 72 hrs and the rate of recovery growth was
taken as a criterion to select the highly salt tolerant genotypes by using Zdistribution
analysis.
Results revealed that genotypes such as: Izraa 10, Izraa 15, and Izraa 18
could be classified as salt tolerant genotypes which showed higher recovery
growth and the least growth reduction over the control. Whereas a genotype
such as Izraa 22 was grouped as salt sensitive one where the percent growth
reduction over the control was greater, indicating that this genotype has low
recovery growth ability.
Our results suggest that the proposed screening technique is rapid, effective,
and match the natural screening.
