Effect Of Zinc Application On Growth,the Accumulation And Distribution Of Cadmium In Winter Wheat And The Speciation Of Cadmium In Soil

Cadmium(Cd)is a heavy metal element with high toxicity and strong migration ability.It could enter the human body through the food chain to endanger human health.Zinc(Zn)is an essential nutrient for plant growth and can participate in the synthesis of various proteins.Zn competes with Cd in the uptake of plants.Therefore,Zn could inhibit the uptake of Cd by plants.In this study,wheat was used as experimental material.Nutrient liquid culture,pot culture and root box culture were conducted to explore the effects of zinc application on the distribution of Cd in soil and the uptake,transport and accumulation of Cd in wheat.The main conclusions were that:1.Cd inhibited the growth of wheat,resulting in the decrease of wheat biomass and the blockage of root growth.In hydroponic experiment,adding 8 and 15 ?mol L-1 of Zn nutrient solution could significantly increase the biomass of wheat roots and shoots.Zn application increased the root length and surface area of wheat,and Zn alleviated the stress of Cd on wheat root growth.2.Zn application could reduce the absorption and accumulation of Cd in wheat.In hydroponic experiment,Zn application significantly reduced the Cd concentration in roots and shoots and the accumulation of cadmium in roots.In pot experiment,Zn spraying on leaves significantly reduced the concentration and accumulation of Cd in wheat grains.In root box experiment,10 and 50 10mg·kg-1 of Zn application significantly reduced the concentration and accumulation of Cd in wheat roots at filling stage.At the same time,the accumulation and concentration of Cd in spikes were decreased,and reached a significant level at mg·kg-1 of Zn application.3.Spraying different concentrations of Zn could significantly reduce the translocation factor from glume to grain(TFgiume-grain),and the translocation factor from stem to glume(TFstem-glume)was significantly reduced when spraying 0.1 w/v ZnSO4·7H2O?4.In nutrient solution culture experiment,Zn application could significantly reduce the concentration of Cd in wheat subcellular fractions,and increase the proportion of soluble fractions Cd in root and shoot.Zn decreased the concentration of Cd extracted by ethanol and d-H2O extractable in shoots and roots,increased the concentration of Cd extracted by NaCl and acetic acid in roots,and decreased the concentration of Cd extracted by NaCl in shoots.Zn application reduced the proportion of Cd extracted by d-H2O and ethanol in wheats.Zn increased the proportion of Cd extracted by NaCl in roots and the proportion of Cd extracted by acetic acid in shoots5.In the root-box experiment,the exchangeable Cd concentration in rhizosphere soil was increased.And the effectiveness of Cd in rhizosphere soil was increased at 50 mg·kg-1 of Zn application.The concentration of carbonate-bound Cd in rhizosphere soil and non-rhizosphere soil were decreased,while Zn increased the concentration of organic-bound Cd in rhizosphere soil and decreased the concentration of organic-bound Cd in non-rhizosphere soil.Zn application significantly increased the concentration of residual Cd in non-rhizosphere soil.