Effects Of Cadmium, Lead Stress On Wheat Growth Physiological In Different Textures Of Soil

With the rapid development of the economy, environmental problems become more apparently, and the problems of heavy metal pollution in wheat fields have attracted more and more attention. The effects of Cd and Pb stress in three soils (sandy soil, loam and clay) on the morphology and physiology of wheat were researched systematically in the screenhouse pot experiment, and the differences of the chemical form of Cd and Pb in three textures soil were discussed deeply. The main conclusions were as follows:1. There were three mainly chemical forms of Cd and Pb in three textures soil, including the exchange form, the iron manganese oxide combination pattern and the residual form, and there was the highest correlation between the contents of Cd and Pb of the exchange form in soil and the content of Cd and Pb in wheat. The contents of Cd and Pb of the exchange form in sandy soil were higher than in loam and clay soil. Meanwhile, the contents of Cd and Pb of these combination forms in three textures soil were more in booting and filling stage and less before sowing and in mature stage. There was a higher correlation between the exchange form and other combination forms in sandy soil than in loam and clay.2. With the treatments of different concentrations of Cd and Pb, the soil enzyme activity was much higher in loam, less in clay, and the lowest in sandy soil. The invertase activity with the Cd and Pb stress had no significant difference between different growth stages, but the urease activity had obvious differences. The results indicated that the urease was much sensitive to the Cd and Pb pollution.3. The order of the wheat root activity in different stages was as seedling stage > green returned stage > filling stage > booting stage with the Cd and Pb stress in three textures soil. The growth of wheat was well in sandy soil with the Cd stress, while in sandy soil and clay soil with the Pb stress. All the morphological and physiological indexes of the wheat showed obvious stress effects at Cd≥60mg/kg or Pb≥600mg/kg, for example that the plant height, the root length and the tillering number were less than the control, and the root activity and the chlorophyll content reduced significantly.4. The order of the contents of heavy metals in different organs of wheat was as roots> leaves > stems > grains with the Cd and Pb stress. There was a positive correlation between the contents of Cd and Pb in different organs of wheat and the heavy metals stress concentration. The wheat in booting stage absorbed much more heavy metal. The Cd and Pb contents in different organ of wheat in sandy soil were much higher. And the Cd content in wheat plant in clay was the lowest with the Cd stress, while the Pb content in wheat plant in clay soil and loam was changing with the growth stages with the Pd stress. Addationally, there was the highest correlation between the total contents of Cd and Pb in wheat plant and in the root.