Ameliorative Effects Of Two Low-Cost Curing Agents On Growth Of Two Kinds Of Solanum Tuberosum L. Under Cadmium Stress

A pot experiment was conducted to study ameliorative effects of limestone and hydroxyapatite on soil pollution of Cd to growth of two kinds of Solanum tuberosum L.plants,Zhongshusanhao(fresh-eating type) and Daxiyang(processing type),in red soil.The results showed as follows:1.Cd-pollution in soils resulted in toxicity to growth of Solanum tuberosum L.. Application of both limestone and hydroxyapatite could alleviate toxicity of soil Cd to two kinds of Solanum tuberosum L.A proper application of limestone and hydroxyapatite could increase the heights,single plant yield,leaf chlorophyll contents, SOD activities,and decreased tuber MDA contents in Solanum tuberosum L.plants. Proper application of limestone and hydroxyapatite also increased vitamin C contents, starch contents,protein contents in the tubers,and decreased soluble sugar contents, reducing sugar contents in the tubers,increased tuber processing quality.The best application amounts of limestone,hydroxyapatite in the Cd-polluted soils were higher thanthose in the no-polluted soils.All indexes(growth,physio-biochemistry,quality, respectively) corresponding to the best application amounts of two curing agents had no obvious differences in two Solanum tuberosum L.varieties.Ameliorative effects of hydroxyapatite on soil Cd toxicity to Solanum tuberosum L.were better than those of limestone,and excessively using limestone could influence the growth of tubers to a certain extent.The application amounts of hydroxyapatite were higher than those of limestone,but it is uneconomical.2.If the single plant yield and tuber vitamin C contents were used as the index to evaluate the ameliorative effects of limestone and hydroxyapatite application in this experiment,the best application amount of limestone and hydroxyapatite were 1 g/kg and 4 g/kg to the unpolluted soil,2-4 g/kg and 10-30 g/kg to the soil polluted with Cd at 5 mg/kg,and 4-8 g/kg and 10-30 g/kg to the polluted with Cd at 10 mg/kg, respectively.3.Soil pH values were obviously increased with increasing in application amounts of limestone to the tested soils,but had no obvious changes when hydroxyapatite was applied..The concentrations of cadmium in Solanum tuberosum L. tubers was positive correlated to the concentrations of effective cadmium in soils,the contents of cadmium in Solanum tuberosum L.tubers was higher than the cadmium contents in the stems and leaves of Solanum tuberosum L.With increasing in the application amounts of these two curing agents,the contents of effective cadmium in soils decreased,the cadmium contents in the tissues of Solanum tuberosum L.plants also decreased.Due to application of the two curing agents,the soil effective Cd decreased and the ameliorative effects of limestone and hydroxyapatite application with increasing in soil Cd concentrations.Effects of limestone on decreasing effective soil cadmium were better than those of hydroxyapatite for the same kind of Solanum tuberosum L.Limestone fixed soil effective cadmium through increasing soil pH and changed soil characters,but hydroxyapatite adsorbed and fixed soil effective cadmium through its special crystal structure.