الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
The present work is conducted to study: 1) The salt tolerance of tomato varieties. 2) the sensitivity of some selected varieties of tomato which show wide range of salt tolerance to cobalt concentration. Also, toxicity symptoms due to high rate of cobalt application are considered. 3) The interaction between salinity and cobalt on the growth, content and uptake of Na, Cl, Co, Fe and Mn by the selected varieties. 4) The effect of different concentrations of cobalt and NaCl on transpiration rate of tomato plant. Experiment I is conducted to study the salt tolerance of tomato varieties edcawy, supermarmand, M/maker, pritchard and strain-B. Experiment 2 is conducted to study the sensitivity of tomato varieties edcawy and monymaker which show a wide range of salt tolerance to cobalt concentration. The plants are treated with cobalt at levels 0.0, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5 and 5 ppm. Experiment 3 is designed to study the interaction between salinity and cobalt on the growth, content and uptake of edcawy (salttolerant) and monymaker (salt-senstive). The plants are treated with NaCl at levels of 1.0 (control) 50, 100 and 200 mM. Cobalt is added in four levels 0, 0.1, 0.25 and 2.5 ppm. Experiment 4 is carried out to study effect of different concentrations of coblate and NaCl on transpiration rate of tomato plant.