الفهرس 
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Abstract
The present study was carried out at the Genetics Department, Faculty of Agriculture, Kafrelsheikh University and Experimental Farm of the Rice Research and Training Center , Sakha Research Station, Kafr El-Sheikh Governorate, Agricultural Research Center and El-Sirw locations Damietta Governorate, Egypt, during the two successive rice growing seasons of 2018 and 2019. For forty-five genotypes of rice were chosen and tested under normal and salinity stress conditions including Egyptian and exotic genotypes - introduced varieties representing a diverse range of genetic materials, to examine the magnitude of yield response of diverse genotypes to salinity stress. Salinity is a main obstacle of rice (Oryza sativa L.) cultivation. The results of this study will be summarized under two main parts , Part (I) is concerned with field evaluation, which includes the mean above-ground biomass performances and genetic variability estimation of the 45 genotypes studied under normal and salinity stress conditions .Part (II) discusses the genetic diversity of germplasm collections as assessed by the screening of the 45 genotypes using SSR-markers.Selecting rice genotypes for salinity tolerance based on phenotypic characteristics alone is inefficient and less reliable, finally will delay progress in rice breeding program. The recent advantages of molecular markers such as simples sequence repeat (SSR) could be used to detect associated salt tolerance markers in rice. This study was conducted to detect genetic variation within some rice genotypes using SSR markers and to identify salt tolerance in the studied genotypes. Forty-five rice genotypes were evaluated for their Morpho-physiological characteristics. Using 21 SSR primers located on chromosome 8, only 18 SSR primers generated polymorphic patterns with a total of 76 alleles, whereas the other 3 primers were monomorphic. The number of alleles per locus ranged from 2 to 6 alleles with an average of 4.22 alleles per locus. The polymorphic information content (PIC) values varied from 0.30 (RM342) to 0.71 (RM6976) with an average PIC of 0.49. Out of the 18 polymorphic markers only 5 primers (RM 6976, RM7631, RM 5556, RM152 and RM342) perfectly distinguished rice genotypes. The best preforming genotypes under salinity stress were N22, IR63731-1-1-4-3-2, GZ 7112-1-2-1-4, FL478, TCCP266-1-3B-10-2-1, IR 65600-127-6-2, IR 68011-15-1-1 and IR 66160-5-2-3-2. Thus, SSR markers is effective to detect high polymorphisms and variations among the rice genotypes, which could facilitate improving salt tolerance of commercial Egyptian rice varieties exhibiting high yield potential. In addition, the selected genotypes might be integrated into breeding programs for salinity tolerance.