الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Two field experiments were carried out during 2011/2012 and 2012/2013 seasons at Agricultural Experimental Station of Desert Research Center (DRC) Located in Ras-Sudr, South Sinai Governorate, Egypt. To study effect of proline foliar applications (control, 20, 40 and 60 ppm) on barley grain hull-less cultivars (Giza129, Giza130 and Giza 131) and barley grain-hulled cultivars (Giza 123, Giza 126 and Giza 2000) under saline conditions (4557 and 8934 ppm) at Ras Sudr. Also, a pot experiment was conducted in a wire house at Radioisotope Department, Nuclear Research Center, Dokki, Cairo, Egypt, during November 2012 to study the distribution and bioaccumulation of 14C- labeled proline into different biochemical components (60 ppm) in two barley cultivars (Giza 126 and Giza 123) under the same conditions of field experiment. Proline had a positive effect on growth, yield and biochemical components in barley cultivars. Giza123 was the best cultivar compared with Giza126. With respect of free amino acids, data showed that thirty three acids were detected in two barley cultivars. The most abundant amino acids noticed were asparagine, proline, alanine, cystine, γ-aminobutyric and lysine. Also, proline treatments led to decrease of malondialdehyde content and quaternary ammonium compounds (glycinebetaine and choline) in barley plants compared with the control. On contrary, the accumulation of quaternary ammonium compounds took the reverse effect with salinity. Proline treatments had a positive effect on antioxidant enzymes under two salinity levels. In this regard, superoxide dismutase and catalase patterns revealed the presence of about five bands for the two barley cultivars under low and high salinity as well as it was increased in band intensity at all samples under high salinity compared with low salinity. Electrophoretic behavior of soluble proteins showed the presence of 12-23 bands with 18-229 kDa. Bands of molecular masses 20, 25, 37, 56, 72 and 149 kDa in two barley cultivars were absent in all proline treatments under low salinity level and accumulated with all doses of proline and control under high salinity level and thus can be used as biomarker to salt tolerance. from the results of pot experiment data revealed that, after 30 days from cultivation, plants were sprayed with 14C- labeled proline. Samples were collected after 3, 6, 24, 48 and 96 hours in addition to 7 and 15 days to study the pathway of proline through distribution and bioaccumulation of 14C- labeled proline into different biochemical components in two barley cultivars under saline conditions. Results showed the maximum values of 14C- recovered in both cultivars were in samples collected after 3 h from 14C- proline application and decreased by time. In both experimental cultivars the highest values of 14C proline were recorded at 3h and decreased by time reaching the lowest values at 15 days under two salinity levels. After washing the plant tissues and separating 14C- proline contents, the plant tissues were used to determine the 14C- residue. In both cultivars the highest values of 14C- residues were recorded at 96 h and decreased by time reaching the lowest values at 15 days under two salinity levels. Also, data revealed that presence of 14C in all plant extracts used in the current study, but the distribution and bioaccumulation were different depending on the type of plant extract and the time of sampling. This proves that proline had clear role in the biosynthesis of many important biochemical components of the two barley cultivars under saline conditions. The highest amount of 14C was found in E1 extract in roots and shoots of two barley cultivars compared with the other plant extracts. We can benefit from current study in alleviate the adverse effects of saline stress on barley plants under Ras Sudr conditions, by activating the role of induced resistance using proline which had a positive effect on most of the biochemical components.