Copper Toxicity Mechanism, Calcium And Iron To Alleviate Copper Toxicity In The Crop Seedling

The growth and development of plants are seriously damaged by increasing of copper in environment. The experiments were carried out with wheat (yangmai 12),maize(denghai 11), we have studied the effects of copper to physiological-biochemical in roots and leaves of young wheat and yang maize by hydroponic culture, and in the same time we studied detoxification of calcium to the copper toxicity under the same hydroponic culture; We also studied the absorption characters of different copper forms on young wheat and maize plant under Fe deficiency and Fe sufficient treatments, besides we studied effects on iron uptake by young plant of wheat and maize under different concentration coppers and different copper forms. The results were summarized as follows:(1) The growth and development of crop seedlings were restrained in different degrees with the increasing concentration of copper. Decrease of biomass and suffocation of roots growth were the apparent phenomenon of damage of crop seedlings by copper. with the increasing concentration of copper, the biomass of wheat and maize were decreased; the roots of crop seedlings were damaged seriously under the copper treatments: with the increasing concentration of copper, the length,the surface area and the volume of roots of wheat and maize seedlings were all shortened. And the copper also gave effects on the effects of physiological-biochemical in the crop seedlings, the relative permeability of cell membrane and malondialdehyde (MDA) contents in wheat and maize leaves and roots were promoted with increasing copper concentration; the root activity and the chlorophyll contents were decreased under higher copper concentration; the contents of Cu of wheat and maize leaves and roots were promoted with increasing copper concentration. And the change of membrane potential of crop roots was also affected by copper, the depolarization patterns of membrane potential were enhanced with increasing copper concentration, and the happen of membrane potential time was shortened with increasing copper concentration.(2)Addition of calcium into nutrient solution could alleviate the copper toxicity to young wheat plants. Calcium could enhance the biomass of crop seedlings, and increase the length,the surface area and the volume of roots of crop seedlings, and in the same time, calcium could reduce the copper toxicity by changing the physiological-biochemical of wheat and maize: calcium could decrease the assimilation of copper by wheat and maize, reduce the relative permeability of cell membrane and the contents of MDA in wheat and maize leaves and roots of wheat and maize, improve the root activity and the contents of the chlorophyll of wheat and maize.(3)Copper contents in wheat and maize seedlings were added with increasing copper concentration under Fe deficiency treatment; and the contents of copper in roots were notably higher than shoots of wheat and maize. Inorganic copper was the easiest absorbed by young plant of wheat and maize, and most of Cu contents were transferred to shoots. EDTA-Cu was the most difficulty assimilated by crop seedlings, and the transfer of copper to shoots was the least. The gross of assimilation of copper by organic complex coppers was higher, and most of copper was accumulated in roots of wheat and maize, the transfer proportion to shoots was lower. Between five different organic complex coppers treatments, the assimilation of copper by wheat and maize was the lowest under EDTA-Cu treatment, but the relative contents of copper by transferred to shoots were the highest.(4)Copper contents in crop seedlings were increased with increasing copper concentration under Fe sufficient treatment, and the contents of iron in roots were notably higher than shoots under any concentration of copper; the accumulation of iron in crop seedlings was affected by the forms of copper, iron was easier absorbed by yang plants under organic complex coppers treatments than under inorganic copper treatment, moreover, the accumulation of iron in roots was higher than in shoots under organic complex coppers treatments or under inorganic copper treatment.(5)Increasing Fe can visibly decrease copper contents in the plant, and more copper contents stayed in the roots, less were transferred to shoots, so organic complex coppers can decrease copper toxicity to young maize plant. Organic complex coppers gave accelerating effects on copper contents by crop seedlings assimilated, and the assimilated copper was mostly accumulated in roots, result showed that organic complex copper was not propitious to transfer copper to shoots.