Effects Of Different PH And Organic Acids On Crops Seedlings Under The Stress Of Heavy Metals

Low molecular organic acids are commonly present and become an important factor in affecting transformation and transfer of heavy metals in environment. Solution culture experiments were conducted to study the effects of four organic acids(citric acid,oxalic acid,tartaric acid,malic acid ) on toxicity of wheat (Yangmai 12) and maize (Denghai11) seedlings caused by the stress of heavy metals (cadmium,copper,nickel) under two pH levels (pH4.0 and pH6.0). The results were summarized as follows:(1) Biomass of crop seedlings were severely affected by heavy metals and application of organic acids could relieve the toxicity. Except the biomass of wheat and maize seedlings were severely decreased with malic acid application under the stress of Cd,, the four organic acids led to increase of plant biomass under the stress of three heavy metals at two different pH levels, and moreover, the effects of the organic acids had significant difference. As far as the root/shoot radio was concerned, effects of different organic acids on the biomass of aerial parts under heavy metals stress was different from that of underground parts. For example, with Cd stress at pH4.0, citric acid tended to reduce the toxicity to shoots, while oxalic acid and tartaric acid were obviously favorable to reduce the toxicity to roots. Citric acid and malic acid separately reduced the Cd toxicity to the biomass of the roots and the shoots at pH6.0.(2) Organic acids had relatively great effects to growth of the roots under the stress of heavy metals. All organic acids under the stress of Cd had positive effects on the length...