[Physiological and Molecular Study of The tolerance of Some local Potato varieties (Solanum tuberosum) to Salinity Stress]

The research work was conducted in Aby Jarash Farm, which belongs to the Faculty of Agriculture, Damascus University, during the two growing seasons (2009/2010 _ 2010/2011), in order to evaluate the response of three potato varieties (Sponta, Draga and Diamont) for NaCl-induced salinity stress. The experiment was laid according to Randomized Complete Block Design (RCBD) with tow replications. The varieties were cultivated in Lysemiters filed in sand and gravel (2:1 respectively), where one variety was allocated in one Lysimeter with tow replicates for both the treatments and control (Without salt). The treatment of salinity stress was applied after one month from planting date, via irrigation by different salt solutions (50, 100, 150 and 200 mM NaCl) from the time of application till the physiological maturity. The performance of the investigated varieties was assessed based on various morphological, physiological and biochemical parameters. Increased the concentration of salt (NaCl) caused a significant reduction in plant height, leaf dry weight and the relative water content (RWC%) and caused a significant increase in sodium ion level (Na+) in all the studied varieties. A remarkable increase in proline content was observed in all the investigated varieties. In general, the was a variability in salinity stress tolerance among the varieties. The variety Sponta was more tolerant followed by Draga and Diamont, which was the most susceptible one. The research work also aimed to determine the dendrogram among the investigated potato varieties using Simple Sequence Repeats technique (SSR), to establish a data base for the future genetic studies in the breeding and genetic improvement programs for potato. The results revealed based on (14) primers that there was a polymorphism by 92.85% , where the studied varieties were divided into two groups according to the tree cluster (Sponta and Draga) in the one group, (Diamont) in the secand group.