Effects Of Different Concentrations Of Cd On Physiological And Biochemical Characteritics In Corn And Soil Microbial And Enzyme Activity Under Drought Stress

With the development of industry and agriculture, there is a large number of heavy metal cadmium that enters into the soil and accumulates in the soil, so soil enzymes, microbe and respiration are affected. Corn roots can absorb cadmium in the soil and transferred to stems, leaves, seeds, and finally enter the body through the food chain, affecting people’s health. Droughts occur every year all over the country different degrees of inconsistency where drought, crop growth and development impact and cuts, and even never produced hit areas. The test under potted conditions, test materials dongdan80, using a split-plot experimental design, with different heavy metals Cd concentrations of soil solution and jointing-large bell, large bell-tasseling silking, tasseling spit silk-mature drought stress treatment, maize under drought stress at different growth stages with different concentrations of Cd on corn yield, physiological and biochemical indexes, each part of the cadmium content of corn, three kinds of soil microorganisms (bacteria, actinomycetes, fungi) total, soil enzyme activity and soil respiration effects. Of cadmium contaminated maize yield under drought conditions improve to provide a theoretical basis and technical support. The main results of this test are as follows:(1) In the corn throughout the growing season, the heavy metal cadmium treatment and treatment are different water gradients have a greater impact on the morphological index maize. Double stress and the effects of stress than under a single large. Especially jointing-large bell severe drought (A3), and high concentrations of Cd (≥50mg.kg-1) plant height and ear height impact is very significant. The large bell-tasseling silking stage of severe drought and cadmium concentrations≥50mg.kg-1treatment under maize yield than the control, there are significant differences.(2) Plant material absorbing light energy in photosynthesis is chlorophyll, and vegetation for light use are directly related. Corn whole growth period, cadmium concentrations≤15mg.kg-1leaf chlorophyll increased with the degree of drought decreased in jointing-large bell fell the most significant; cadmium concentrations≥50mg.kg-1chlorophyll content decreased, with control there are significant differences. Chlorophyll a period before the big bell decreased significantly after cadmium and drought stress had no effect on its basic. Three growth period net photosynthetic rate, transpiration rate, stomatal conductance in drought stress than cadmium concentrations≤5mg.kg-1under the control big deal, promote the role of photosynthetic characteristics; high concentrations of cadmium inhibition of photosynthesis.(3) Double stress treatment soluble protein in corn growth stages, with the increasing stress levels were increased, and more than a single stress. Proline at jointing-large bell double stress changes of relatively flat; after large bell, low concentrations of cadmium (≤1mg.kg-1) treatment with increased levels of drought proline lower than the control, corn small leaf cells the damage; handle its high concentration of cadmium increased significantly, with a significant difference from the control. Throughout the growth period with the enhancement of malondialdehyde stress levels rise, the corn plant membrane lipid peroxidation serious extent of injury; remove active oxygen plants protective enzyme system SOD, POD, CAT and other enzyme activity under the combined stress of cadmium and drought increased, thereby protecting the membrane system. SOD activity in the three growth stages between each treatment were significant differences; while POD, CAT jointing-large bell, large bell-tasseling silking significant difference, tasseling silking-maturity difference was not significant.(4) Cadmium and Water Deficit, the total number of three soil microbial activity in the soil, soil respiration were significant differences in the level. Treatment with different concentrations of Cd on soil converting enzyme inhibition, while soil respiration and soil enzyme Catalase, along with the increase of Cd concentration after the first promotion of suppression. Wherein when the Cd concentration≤5mg.kg-1total three microorganisms in soil and soil respiration can promote high concentrations (≥15mg.kg-1) of its inhibition; Cd concentrations≤1mg.kg-1soil catalase has promoted, with elevated concentrations of cadmium inhibition of its more obvious. Three total soil microorganisms, soil catalase activity, soil respiration at different growth stages of corn were positively correlated with soil moisture, while corn tasseling silking invertase activity in soil-soil moisture affected by maturity small, did not reach significant levels.(5) The distribution of cadmium content in various parts of the corn is like that, there is the most cadimium in root of maze, then is in leaf, after that is in stem, the least is in grain. and Water under cadmium stress increases with the level of stress each part of the cadmium content of corn increased. Moderate drought and severe droughts promote corn on cadmium uptake and transport.In summary, cadmium and drought combined pollution on the growth and development of corn to produce some toxic effects, and the extent of toxic cadmium combined stress is greater than a single stress and drought. So presumably both cadmium and drought stress on the performance of certain complex synergistic toxic effects.