الفهرس 
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Abstract
This work aimed to study the effect of different Zn concentrations (4, 8, 12 and 16 mM Zn) on the different organs (roots, stems, leaves and pods, in addition to the root nodules) of five broad bean genotypes (Assiut 95/2, Assiut 85/37, Assiut 125, Assiut 84 and Assiut asasy). Dry weight, tissue water content, root/shoot dry weight ratio and contents of photosynthetic pigments were estimated as growth parameters and the contents of carbohydrates, proteins, total free amino acids and proline were also estimated, as well as the contents of some elements (Ca, Mg, K, Zn, Fe, Al, S, P, Cl, Si and Cu). The obtained results could be summarized in the following points:
In genotype Assiut 95/2 the data of dry matter yield showed that the nodules, roots, stems and leaves were stimulated by Zn treatment whatever the concentration used is. However, there are marked differences in Zn concentration that caused the highest stimulation. The highest stimulation in the dry matter yield was observed at 8 mM Zn treatment in nodules and stems, at 12 mM Zn in leaves and at 16 mM Zn in roots. The crop yield increased progressively as the Zn increased in the soil, which was more pronounced at the highest level used. At the level of 16 mM Zn the percent increase in crop yield was 45.34% over the control.
In genotype Assiut 85/37 the five tested plant organs showed high increase in the dry matter yield in response to the different tested Zn concentrations. 8 mM Zn resulted in the highest increase in the dry matter of nodules of this genotype while 12 mM Zn was the optimum
concentration for the roots, stems, leaves and pods. The increase in the crop yield at 12 mM Zn treatment reached about 33% over the control.
The dry matter yield of the genotype Assiut 125 was surprising because while the nodules, roots and stems were stimulated markedly and progressively by Zn treatment, leaves were not, especially at the highest doses of the element. This genotype doubled its crop yield at the level of 4 mM Zn and it increased the crop yield production by 64.6% and 42.48% at the levels of 8 and 12 mM Zn. It maintained the crop yield around the control value at the highest concentration of Zn.