The Impacts Of Different Forms Of Calcium On Physiological Characters Of Brassica Chinensis L. Under The Acid Rain Stress

With the rapid development of industry,acid rain has become a global environmental problem and China has become one of the acid rain areas around the world.The acid rain caused serious effects on food production in China.Brassica Chinensis L.,one of the important economic crops in northeast China,is also one of vegetable sensitive to be influenced by acid rain.At present,researches force on the impact of different degree of acid rain on the growth and physiological characters of Brassica Chinensis L..And these related research found that the addition of calcium and reduce the influence of acid rain on Brassica Chinensis L.in the areas where affected by acid rain.However,it is still unclear how the additional of calcium affect the forms of calcium in Brassica Chinensis L.,and how the different forms of calcium in Brassica Chinensis L.influence on physiological characters under the acid rain stress.To achieve these aims,the contents and composition of different forms of calcium in Brassica Chinensis L.under the acid rain stress were analysis in this study.Combining with the generalized linear model（GLM）and the Akaike information criterion（AIC）test,the effects of different forms of calcium in Brassica Chinensis L.on the growth and physiological indexes were evaluated,and suitable suggestion for planting Brassica Chinensis L.in areas where influenced by acid rain were provided.The results showed that with the increasing degree of acid rain stress,the concentration of C₂O₄-Ca in Brassica Chinensis L.increased obviously at beginning stage of plant influenced by acid rain.However,the other four forms of calcium increased generally in the middle stage of plant influenced by acid rain.Unlike the variation of different forms of calcium,the height of Brassica Chinensis L.increased obviously in the beginning and middle stage of acid rain stress,and the weight,chlorophyll content and soluble sugar of Brassica Chinensis L.increased continuously with the increasing of acid rain stress time.Acid rain stress caused the relationship between different forms of calcium in Brassica Chinensis L.also changed obviously.In the beginning of acid rain influenced on Brassica Chinensis L.,the composition of different forms of calcium in plants were also obvious different with those have none influenced from acid rain stress.And the C₂O₄-Ca increased was the major factor that caused total calcium increased.And there may existed some transformation process between Ca（NO₃）₂/CaCl₂ and dissolved-Ca,i.e.part of dissolved-Ca changed to Ca（NO₃）₂/CaCl_2.With the increasing time of acid rain stress,the transformation of different forms of calcium in Brassica Chinensis L.became more obviously,and the correlation coefficients between different forms of calcium were obvious increased.In the end of acid rain stress,the Brassica Chinensis L.gradually adapt to the environment,and the transformation between different forms of calcium became weaken,with the correlation coefficients between different forms of calcium decreased obviously.In this stage,the increase of different forms of calcium in Brassica Chinensis L.may mainly cause by the direct input of calcium from soils.Acid rain also led the impact of different forms of calcium on different physiological characters of Brassica Chinensis L.changed.Before influenced by acid rain stress,dissolved-Ca,pectinate-Ca and PO₄-Ca were the major factors that influence the physiological characters of Brassica Chinensis L.With the time increasing,acid rain stress increased the impact of dissolved-Ca and C₂O₄-Ca on physiological characters of Brassica Chinensis L..In the end of acid rain stress,the impact of the pectinate-Ca and PO₄-Ca on physiological characters of Brassica Chinensis L.obviously increased,and these two forms of Ca became the major forms of calcium influenced on physiological characters of Brassica Chinensis L..In summary,the results in this study could also provide some suggestions on how to add calcium fertilizer during the cultivation of Brassica Chinensis L.in northeast China.In the areas where not influenced by acid rain,dissolved-Ca,pectinate-Ca and PO₄-Ca were the major forms of calcium that influenced the Brassica Chinensis L.growth,more fertilizer of these three forms of calcium could increase the production of Brassica Chinensis L..However,in the area where influenced by acid rain,the physiological characters of Brassica Chinensis L.could be adjusted by pectinate-Ca and PO₄-Ca,and more these two forms of calcium could remain the production of Brassica Chinensis L.under the acid rain stress.