الفهرس 
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Abstract
Barley, (Hordeum sp.) is a crop of worldwide importance, it is considered to be one of the most suitable crops that can be grown over a wide range of adverse conditions than other grain crops, it is grown in environments ranging from the deserts of the Middle East to the high elevations of the Himalayas and it represented the main crop grown on large scale in the rain fed areas of Egypt and Libya as well. Barley (Hordeum vulgare L.) is an important crop used as feed for animals, brewing malt, and human food. Its importance derives from the ability to grow and produce in marginal environments, which are often characterized by drought, low temperature and salinity.
The improvement of abiotic stress tolerance in barley depends largely on exploiting the available genetic variation in cultivated (Hordeum vulgare subsp. vulgare) and wild barley (H. vulgare subsp. Spontaneum). The genetic heterogeneity of wild populations has long been recognized as an important mechanism of adaptation to the environment; however, the commercial production of barley is based on a relatively narrow genetic base. Barley breeders have, accordingly, been interested in broadening the genetic base of the crop without disrupting the genetic architecture essential for quality. Hordeum vulgare subsp. spontaneum, the ancestor of cultivated barleys has been the subject of considerable genetic analysis for abiotic stress resistance traits, biotic stress resistance traits, and quality traits.
The objectives of this study were to locate and collect wild barley accessions of the Hordeum species from certain regions in north western coast of Egypt beginning of the Burg Al-Arab, passing through the Sidi Abdel Rahman, Foca, Marsa Matruh, Sidi Brani, Sallom, to establish database use for the purposes of breeding and improvement programs. In order to achieve such a purpose one hundred and eighty samples of barley representing six locations were collected from Burg Al-Arab (52Km from Alexandria) to El-Sallom (480Km from Alexandria) and were subjected to determine the wild barley species witch present in the study area, then wild barley were subjected to morphological measurements in order to identify their taxonomical position. In addition, six samples of soil were collected from different localities for soil analysis and ecological studies.
To establish a data base for both wild and cultivated barley cytological examination, isozyme electrophoresis and molecular genetic fingerprints (RAPD-PCR), phylogenetics relationships analysis; and finally soil stress experiment; were conducted. The results obtained could be summarized as follows:
Classification of wild Barley: Although the morphological characterization was not the ultimate goal of this study, it was carried out to be the base line to interrupt the taxonomy of wild barley. According to Vivi Tackholm (1974) and Loutfy Boulos (1999) references, the collected wild barley were related to H. spontaneum and H. marinum species.
Morphological studies: The results obtained from this investigation revealed that number of tillers per plant, spike length (cm) and the weight of 100– kernel (gm) traits displayed highly significant differences between the tested species in the six different localities, but there were insignificant difference in plant height (cm), and number of spikelet per spike. Moreover data obtained from the analysis of variance of different traits indicated that species Hordeum spontaneum and Hordeum marinum have considerable amounts of morphmetric variation (Quantitative morphological characters).
Soil Analysis and relative distribution: Soil analysis results indicated that soil salinity is the most important ecological factor affecting Hordeum species biology in north western coast of Egypt. Same feature was encountered for all samples pH (ranged between 7.73 and 7.98) these high pH values may be due to the near of this soil of the sea. The highest relative distribution of H.spontaneum found in El-Sallom which was the highest salinity locality (Na=7.5 milligram equivalent/Litter and EC=5376 p.p.m); and the highest relative distribution of H.marinum found in Marsa-Matrouh (Na=6.3 milligram equivalent/Litter and EC= 4416 p.p.m).
Cytological study: Chromosome number, chromosome analyses including long - short arm ratio and total fractional ratio (TF %) were done for each species (H.marinum, H.spontaneum and H.vulgare). The obtained results clearly showed that the chromosome number 2n=14, and this number was proven to be constant from one species to another, Chromosome complement of diploid H. marinum and H.spontaneum were consisted of five sub median and two median chromosome pairs, while H.vulgare consisted of three sub median and four median chromosome pairs. In addition the karyotype as an ideogram was drawn for all species. H. marinum was supposed to be the most advanced due to having the smallest TF% and H. vulgare possessing the largest TF% was considered as the most primitive one. Results indicated strongly that H. spontaneum is closely related to H.vulgare since they have the highest number of chromosome type similarity.
Biochemical study: Analysis of the leaves peroxidase isozymes revealed two bands for all the tested species, band 1and 2, however, band No. 3 were found only in all H. marinum samples collected from the different localities and it can be considered as a marker band for this species. The analysis of phylogenetic relationship was capable to classify the studied fourteen plant leaf samples into two big clusters, cluster No.1 contained eight plant samples and was divided into two sub-clusters, which were the two domesticated barley (Giza126, Giza2000) in the first sub-cluster, and the 6-different localities samples of Hordeum spontaneum were in second sub-cluster. Cluster No.2 contained the six plant samples for the 6-different localities of H. marinum. from these results we can conclude that there was high degree of similarity between the domesticated barley (H.vulgare) and the wild species H. spontaneum.
Molecular genetic study: The results demonstrated that RAPD analyses are useful for evaluation of genetic diversity between different wild and domesticated barley. Based on the RAPD analysis using five random primers, it was clear that the wild type of barley H. spontaneum from Marsa-Matrouh locality offers the possibility of obtaining an appropriate and successful hybrid with domesticated populations. Moreover in this study it was obvious that the dendrogram based on RAPD markers was fully in agreement with the dendrogram based on peroxidase isozymes.