الفهرس 
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Abstract
Salinity is one of the main reasons in the deterioration of arable lands. Irrigation, fertilizers and other modern agricultural practices have increased salinity and sodicity so much that the ability of many soils to grow crops has been severely reduced and sometimes eliminated. This work was carried out, in the National Institute of Laser Enhanced Sciences, (NILES), Cairo University during 2002-2003 season .In the present work. Wheat plants, Triticum asetivum, were grown in soil having different salinity levels. Mixed amounts of NaCl, Ca Cl2, and Mg SO4 with 1 : 1 : 0.5 ratios were added to the soil at concentrations of 2000, 4000, and 6000 ppm. Na, Mg and Ca concentration in different parts of the plant (leaves, roots and grains) as well as soil at different growth stages (50, 90 and 150 days from sowing) were determined in a control group which has been grown without any treatment, and in other groups treated by Si in the form of sodium meta silicate (Na2 Si O3.5H2O). These treatments were added to the soil and foliary (with two concentration 500,1000 ppm SiO2 for both methods) to reduce salinity hazards. Salinity effects on the plant growth, yield, and some certain physiological responses (total sugars, total free amino acids, total soluble phenols and plant pigments) during different plant growth stages (50, 90 and 150 days after sowing) were also reported. LIBS is used as a fast, accurate and simple technique for qualitative and quantitative elemental analysis. Laser induced breakdown spectra are obtained from different fresh plant parts (leaves, roots and grains) as well as from the soil control and treated samples. After maturation, (150 days after sowing), plant spikes were collected, grains were grinded then pressed into tablets to be analyzed. Nd: YAG pulsed laser source (100 mJ / pulse, Δt = 7 ns at λ= 1064 nm), is used for producing plasma onto each sample. Echelle spectrometer coupled to an ICCD camera as a detector was used for plasma emission spectral analysis. The obtained results have been confirmed using the standard conventional analytical techniques Inductively Coupled Plasma (ICP) as well as wet chemistry.