Effects Of Different Agriculture Measures On Alleviating The Toxicity Of Cadmium, Lead And Chromium To Wheat

With the development of society economy and the severity of the agricultural environment pollution, heavy metal pollution and control in wheat have received more and more attention. In this paper, seven agriculture measures(nitrogen, phosphorus, potassium, hen dung, calcium carbonate, fly ash, maize stalk) and three heavy metals(Cd, Pb, Cr) were studied.The experiments had been done by pot culture and plot comparison using the wheat breed of (Triticum aestivum L.) Aikang 58. Effects of different agriculture measures on the growth physiology, contents of Cd, Pb and Cr in autumn seeds as well as yield properties were studied. At the same time, the physiological mechanism of alleviating the heavy metal toxicity by different agriculture measures to wheat was investigated in detail and mulriple renovation as well as plot comparison experiments were also done. The main results were as follows:1. It was indicated that low concentration of Cd could stimulate the growth of wheat. The indices were enhanced firstly and then diminished under the higher Cd concentration.The growth of wheat was inhibited by both Pb and Cr stress. Detailedly, compared to the controls, the lengthes of shoot and root, dry weights of shoot and root, root activity and chlorophyll content decreased by contraries of the activities increasing of peroxidase(POD) and superoxide dismutase(SOD) isoenzymes as well as malondialdehyde(MDA) content as the concentrations of Pb and Cr increased. The root was more strongly inhibited by Cd, Pb and Cr than shoot.2. By in-door and out-door pot experiments, the growth of wheat seedling was significantly promoted by adding hen dung, maize stalk, fly ash and calcium carbonate in the 0.6 mg/kg Cd polluted soil. The effects of the four matters to reduce grain Cd content followed by the order of hen dung>maize stalk>fly ash>calcium carbonate. Detailedly, 2.0 g/kg hen dung, 3.0 g/kg～4.0 g/kg maize stalk, 50 g/kg～100 g/kg fly ash and 1.0 g/kg calcium carbonate could effectively alleviate the 0.6 mg/kg Cd toxicity. At the same time, 2.0～3.0 g/kg hen dung, 4.0 g/kg～6.0 g/kg maize stalk, 0.5 g/kg phosphorus and 100 g/kg fly ash could effectively alleviate the 30 mg/kg Cd toxicity.3. All the measures could effectively reduce the grain Pb content when the concentration of Pb was 350 mg/kg, but relatively speaking, the effects of maize stalk, fly ash and nitrogen were better. Generally comparing the seven measures, 3.0 g/kg～6.0 g/kg maize stalk, 50 g/kg fly ash and 0.2～0.5 g/kg nitrogen could effectively alleviate the 350 mg/kg Pb toxicity. At the same time, 2.0～3.0 g/kg hen dung, 3.0 g/kg～4.0 g/kg maize stalk and 50 g/kg～100 g/kg fly ash could effectively alleviate the 600 mg/kg Pb toxicity.4. All the measures except potassium could effectively reduce the grain Cr content when the concentration of Cr was 250 mg/kg. Considering the physiological indices of wheat seedling, the grain Cr content as well as yield properties, the effects of 2.0 g/kg hen dung, 0.5 g/kg calcium carbonate and 3.0 g/kg～6.0 g/kg maize stalk could effectively alleviate the 250 mg/kg Cr toxicity. At the same time, 3.0 g/kg hen dung, 1.0 g/kg calcium carbonate, 100 g/kg fly ash and 6.0 g/kg～8.0 g/kg maize stalk could effectively alleviate the 400 mg/kg Cr toxicity.5. By plot comparison experiments, the three measures could effectively reduce the content of the six heavy metals in wheat grain, and their effects followed by the order of hen dung>maize stalk>fly ash. Compared to the controls, the content of the six heavy metals in wheat grain were significantly reduced by 22.08, 21.03, 18.74 percent. Detailedly, hen dung was better in reducing grain As,Cu,Pb,Zn contents, maize stalk was better in reducing grain Cr,Cu,Pb,Zn contents and fly ash was better in reducing grain As,Cd,Pb,Zn contents.The three measures could increase wheat yields in some degree, hen dung and maize stalk were better.6. In the mulriple renovation of Cd, Pb, Cr experiments, the optimal treatments were A1B1C2, A2B1C2, and A1B1C2 when the concentration of Cd, Pb, Cr were 20 mg/kg, 500 mg/kg, and 300 mg/kg respectively. In other words, the combine of 3.0 g/kg hen dung, 50 g/kg fly ash, 6.0 g/kg maize stalk could effectively alleviate the Cd toxicity, the combine of 5.0 g/kg hen dung, 50 g/kg fly ash, 6.0 g/kg maize stalk could effectively alleviate the Pb toxicity, the combine of 50 g/kg fly ash, 1.0 g/kg calcium carbonate, 6.0 g/kg maize stalk could effectively alleviate the Cr toxicity.