Evaluation the Response of Some Wheat Genotypes at Seedling Stage to Water Stress

This study was carried out at the Faculty of Agriculture, Damascus University, and ACSAD during the year 2001 – 2002 in order to assess the genetic variability of twenty wheat genotypes for osmotic stress tolerance by using PEG-6000 as a water stress induced tool. This trial aimed to develop a semi-natural rapid and effective screening technique in which the optimum induction as well as lethal levels of osmotic stress are well defined . The results revealed that the treatments –0.4 MPa and –1.5 MPa were the optimum induction and lethal levels of osmotic stress, respectively.

Development of an efficient screening tool to assess the genetic variability for NaCl – induced salinity stress among Sorghum (Sorghumbicolor [L.]Moench) genotypes at early growth stages (seedling)

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 sorghum 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.