Reasons Of Elevation Of Winter Wheat Growth And Znic Uptake By Calcium Chloride And Magnesium Chloride On Calcareous Soil

Factors as high calcium (Ca) carbonate content and high pH of calcareous soil restrict theabsorption of zinc (Zn) by wheat in northern China. Based on the previous research whichfound that excessive application of magnesium chloride (MgCl2) or calcium chloride (CaCl2)significantly increased grain Zn concentration of winter wheat, the combined application ofnitrogen (N) and MgCl2experiment was designed to investigate the effects of MgCl2onwinter wheat growth, the uptake and utilization of magnesium (Mg) and Zn under different Nlevels; MgCl2(0,0.3,0.6,0.9and1.2g Mg/kg) and MgSO4rates (0,0.3,0.6,0.9and1.2gMg/kg) experiments were also designed to compare effects of MgCl2and MgSO4on winterwheat growth and uptake and utilization of Mg and Zn, and to explore the relevant reasons.Furthermore, a CaCl2(0,0.3,0.6,0.9and1.2g Ca/kg) rate experiment was carried out toinvestigate effects of CaCl2application on winter wheat growth, the uptake and utilization ofCa and Zn, so as to verify the reason why the application of MgCl2or CaCl2improved grainZn concentration of winter wheat. The main obtained results are as follows:Application of MgCl2(0.6g Mg/kg) to N did not significantly influence the grain yield,but further promoted aboveground Zn uptake by winter wheat. Application of MgCl2significantly improved grain Zn concentration by25.9%and31.2%at the0and0.2g N/kg,respectively.Appropriate MgCl2or MgSO4application significantly increased the abovegroundbiomass and grain yield of winter wheat, and at the meantime, significantly increased totalMg uptake, and the Mg concentration in straw and glume. However, MgCl2and MgSO4haddifferent influence upon Zn uptake by wheat. Application of MgCl2significantly decreasedthe soil pH at harvest, and promoted Zn uptake by winter wheat and its transportation to grain,with grain Zn concentration significantly increased from30.1mg kg-1at control to44.3mgkg-1at0.6g Mg kg-1MgCl2treatment. But the application of MgSO4showed no obviouseffects on soil pH or Zn concentration in wheat parts.Appropriate CaCl2application in calcareous soil was also found significantly increasedthe aboveground biomass and grain yield of winter wheat, and total Ca uptake wassignificantly increased by38.6%to91.4%with the increase of CaCl2rates. Being similar with the results of MgCl2rate experiment, application of CaCl2significantly decreased thesoil pH at harvest, and promoted Zn uptake by winter wheat and its transportation to grain.Grain Zn concentration was significantly increased to42.0mg kg-1at0.9g Ca kg-1treatment.Appropriate MgCl2, MgSO4or CaCl2application in calcareous soil was all foundsignificantly increased the aboveground biomass and grain yield of winter wheat, andpromoted the uptake of Mg or Ca by winter wheat. And that the application of MgCl2coulddecrease the soil pH, and improve grain Zn concentration, but the application of MgSO4showed no obvious effects on soil pH or Zn absorption and utilization by winter wheat, whichproved that the possiable reason for the influence on Zn absorption and utilization was thedifference between Cl-and SO42-. The CaCl2rate experiment also proved that theimprovement of grain Zn concentration was due to the chlorine ion, which decreased soil pH,activated Zn in soil, and promoted Zn uptake by winter wheat and its transportation to grain.These results provide useful information for understanding the mechanism of Zn activationand exploring ways to promote the absorption and utilization of Zn by crops on calcareoussoil in dryland.