不同土壤类型马铃薯对镉的富集转运差异研究

Difference of Cadmium Enrichment and Transportation of Potato in Different Types of Soils

喀斯特碳酸盐岩地区具有典型的重金属镉(Cadmium)地质高背景特征,为探明区域地带性土壤黄壤和岩成土壤石灰性土上种植马铃薯对Cd胁迫的响应,利用黄壤和石灰性土进行盆栽试验,土壤Cd浓度梯度设置为0.3,0.6,1.2,2.4和4.8 mg/kg,研究Cd胁迫下马铃薯不同生长时期各部位Cd含量的变化,采用富集和转运系数分析Cd在土壤-马铃薯系统中的迁移转化特性。结果表明,随着土壤Cd浓度增加,马铃薯植株各部位Cd含量上升,表现为根>茎>叶>块茎;随着马铃薯生长期加长,植株对Cd的富集能力逐渐增强,富集系数表现为成熟期>淀粉积累期>块茎膨大期>苗期>花期;马铃薯植株Cd富集系数平均为6.90(黄壤)和3.66(石灰性土),块茎Cd富集系数为0.95(黄壤)和0.36(石灰性土);各生长期Cd转运系数表现出根-茎>根-叶>根-块茎,在黄壤和石灰性土上植株转运系数均值为0.89和0.66,块茎转运系数均值为0.11和0.17,总体表现为黄壤上马铃薯的富集和转运系数大于石灰性土。在Cd胁迫下,马铃薯植株比块茎(可食部分)有相对较强的富集和转运能力,除黄壤马铃薯成熟期富集系数外,两种土壤上块茎的富集系数和转运系数均小于1,整体表现出高富集、低转运的特点。

A karst carbonate rock-distributed region is characterized by high geological background of cadmium(Cd).Pot experiments were conducted to study the response of potato under Cd stress in yellow soil(zonal soil)and calcareous soil(lithogenic soil).Cd concentration of soils was set as 0.3,0.6,1.2,2.4 and 4.8 mg/kg,and the change of Cd content in different potato plant parts and in different growth stages were determined.Enrichment and transportation coefficients were used to analyze the migration and transformation characteristics of Cd in soil-potato system.Cd content of potato plant increased with the rising of soil Cd concentration,and ranked as:roots>stems>leaves>tubers.Cd enrichment coefficient of potato was presented as:maturity>starch accumulation>tuber bulking>seedling>flowering,and Cd enrichment capacity increased as the growth of potato.The mean Cd enrichment coefficient of potato plant was 6.90(yellow soil)and 3.66(calcareous soil),and the mean Cd enrichment coefficient of potato tubers was 0.95(yellow soil)and 0.36(calcareous soil).Cd transportation coefficient was:root-stem>root-leaf>root-tuber.The mean Cd transportation coefficient of potato plant was 0.89(yellow soil)and 0.66(calcareous soil),and the mean transportation coefficient of tubers was 0.11(yellow soil)and 0.17(calcareous soil).Overall,the enrichment and transportation capacities was stronger in yellow soil than that in calcareous soil.Under Cd stress,plant showed much higher Cd enrichment and transportation capacities than those of tubers(edible part).Cd enrichment and transportation coefficients of potato tubers were all less than 1,except for enrichment coefficient of maturity time in yellow soil,indicating higher enrichment and lower transportation characteristics.