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Abstract Summary Many heavy metals can find their way to the soil in high rates and so they act as permanent sources of heavy metals pollution forall the types of life either through the soil or on the earth plant itself. This study aims to investigate the effects due to some of those heavy elements that may act as soil pollutants ( Zn, Co and Cr ) , applied at high rates on soil and plant. The effects were considered with respect to cotton, carrot, sorghum, wheat, clover and bean, also heavy metals movement and transformations in soils were evaluated through theses experiments as follows: Exp ( I ): Germination experiment: This experiment was conducted using a sand culture technique where the germinated seeds were to increasing applications of tested heavy metals, the obtained results showed the following: Zinc applications did not adversely affected the germination percentage of bean seeds even at its highest rate (500 mg.kg-l) , while the germination of clover, cotton and carrot was reduced with Zn rates as low as 50 mg.kg-1. Germination of both sorghum and wheat seeds was adversely affected with Zn applications at a rate of 100 mg.kg !. Cobalt applications adversely affected seeds germination in the order I) Bean 20 mg.kg l Zn or more III) Clover, cotton and carrot 1O’mg.kg! Zn or more Chromium application did not adversely affect bean germination even at its highest rate of applications. On the other hand the germination percentage of all the anther tested seeds (sorghum, wheat, clover, cotton and carrot) was diminished even with the lowest rate of Cr application (lO mg.kg-I ) Experiment (II) : Plant growth and utilization of elements: This experiment was conducted under green house conditions, using soils representing the alluvial clay, calcareous and sandy soils. Growth, dry matter yield and concentration ( content) as well as total uptake of Zn, Co and Cr by sorghum and carrot plants grown on the above mentioned soils supplied with increasing rates of these elements were evaluated . The obtained results showed the following: Dry matter yield: ** Dry matter yield of sorghum gained from the tested three soils respond to Zinc application in quiet different trends as follows: * In alluvial clayey soil, sorghum plants slightly and progressively responded to Zn applications up to the highest rate (400 mg. kg-1 ) . Where the maximum increase (28 %) occurred. * With respect to the calcareous soil, though the maximum increase (18 %) was yielded with Zn application at the highest rate, an increase of (17%) occurred with the application rate of 200 mg. Zn.kg-1 soil only. * * The sandy soil showed a maximum response (140/0) corresponding to rate of Zn application ( 100 mg.kgr l) ** Dry matter yield of carrot, positively responded to Zn application up to limits that different from one soil to another as follows: I) Alluvial clay soil up to 100 mg Zn.kg-I II) Calcareous soil up to 150 mg Zn .kg-I III) Sandy soil up to the highest rate (400 mg. kg-I ) Further increases in the rate of application, adversely affected the dry matter yield of carrot in both alluvial and calcareous soils. • • Cobalt application enhanced dry matter yield of sorghum and carrot grown on the tested soils, where the positive effect lasted till a certain level of application according to the following pattern: Sorghum Alluvial clay soil : up to 50 mg.kg-l Calcareous and sandy soil : up to 30 mg.kg-I Carrot up to 30 mg. kg-I up to 40 mg.kg-I With higher rates of application, the dry matter yield was adversely affected. 4 •• Except to Chromium application at the lowest rate (5 mg.kg-1) to carrot grown on the tested soils, all the treatments of Cr with both plants adversely affected the dry matter yield of plants . This true with respect to the tested three soils. Elemental content: Concerning the elemental concentration (content) in plants, the values of Zn, Co and Cr progressively increased in both sorghum and carrot grown on the tested soils with increasing the rate of elemental application. However, there was only one exception with carrot grown on calcareous soil as affected by Co application where its content was maximized with application rate of 40 mg.kg-l Co. Further rates reduced the Co concentration in carrot. Total Uptake: As for total uptake of the tested elements, , results showed that Zn and Cr applications at any rate and to any soil ( except the highest Cr rate i.e. 25 mg.kg”! in case of the sandy soil) progressively increased the total uptake of both elements either in sorghum or in carrot, (particularly in sorghum shoots in case of Zn) . Cobalt application up to certain level increased the total uptake of the element. The higher rates of application yielded an inverse affect. The maximum application rates 100 mg.kg” 1 that positively affected the total Co uptake could be shown as follows: Soil : Sandy calcareous Sorghum 100 40 4:arrot 100 30 Alluvial clay 50 mg.kg! 100 mg.kg-I Translocation in plant: Concerning the rate of elements translocation to upper plant parts (%) results showed more than one trend as follows: Zinc applications to the tested soils enhanced the translocation rate ?f z:n . This was true in case of carrot up to the highest rate of application and up to the third one (l SO mg.kg! ) in case of sorghum . Chromium application at the lowest rate reduced the rate of Cr translocation i.e. the element tended to accumulated in plant roots. This was for both sorghum and carrot grown on all the tested soils. With respect to Cobalt application, the results differed according to the type of soil and type of plant with an almost constant rate of Co translocation in case of the alluvial clay soil. Fe in plant as affected by elemental applications: Results of total Fe uptake as affected by the involved treatments showed the following trends: Zinc as well as Cobalt application at relatively lower rates tended to increase Fe uptake but with higher application rate of both elements, an inverse trend was obvious. However, there was one exception for carrot growth the alluvial soil where Fe uptake was always reduced with Co application at any rate. Chromium application drastically reduced Fe uptake in the alluvial clay soil and to a lower extent in the sandy soil but did not affect it in case of the calcareous soil. P in plant as affected by elemental applications: Phosphate uptake responded to elemental applications in the following trend: Zinc applications up to 1SOmg.kg-I tented to increase P uptake, but with higher rates of Zn application, the reverse was true. Cobalt application adversely affected P uptake in sorghum while Co induced P uptake of carrot when it was applied a relatively low rates ( up to 30 or 40 mg.kg-I ) Chromium application negatively affected P uptake under the different treatments tested. |