稻田冬季杂草稻槎菜的镉积累特性研究

摘要

In order to screen more cadmium hyperaccumulators for cadmium contaminated paddy field remedia-tion,the pot and plot experiments were conducted to study the cadmium accumulation characteristics and ecophysio-logical characteristics of winter weed Lapsana apogonoides in paddy field.The preliminary and further experiments showed that the root biomass,shoot biomass,whole plant biomass and resistance coefficient of L.apogonoides de-creased first and increased later and decreased again with the increase of cadmium concentration in soil,and there was no significant toxic characteristic in any treatment.With the increase of soil cadmium concentration,the cadmi-um contents in root and shoot of L.apogonoides increased.When the soil cadmium concentration was 75 mg /kg,the cadmium contents in shoots of preliminary and further experiments were 1 19.50,1 10.1 1 mg /kg,respectively,which reached the critical value of cadmium hyperaccumulator(100 mg /kg).The root bioconcentration factor(BCF)and shoot BCF were greater than 1 ,and translocation factor(TF)exceeded 1 when the soil cadmium treatment was grea-ter than 0 mg /kg.The cadmium accumulation amounts in root,shoot and whole plant of L.apogonoides increased with the increase of soil cadmium concentration,and had highly significant linear regression relationship with soil cadmium concentration.The further experiment showed the chlorophyll content decreased first and increased later and decreased again with the increase of cadmium concentration in soil,SOD activity increased first and decreased later,and POD activity decreased first and increased later,which were related to the special physiological mechanism of L.apogonoides.In plot experiment,the cadmium accumulation amount in shoot of L.apogonoides was 1.10 -1.13 mg /m2 at soil cadmium level of 2.04 -2.89 mg /kg.Therefore,L.apogonoides was a cadmium hyperaccumulator which could be used to remedy the cadmium contaminated paddy field in winter.%为进一步筛选出更多的适合稻田镉污染修复的镉超富集植物材料，通过盆栽试验和小区试验，对稻田冬季杂草稻槎菜的镉积累特性及其生理生态特性进行了研究。初步试验和验证试验表明，随土壤镉浓度的增加，稻槎菜根系生物量、地上部分生物量、整株生物量及抗性系数呈先降后升再降的趋势，但未表现出明显的毒害特征。稻槎菜根系及地上部分镉含量均随土壤镉浓度的增加而增加。在土壤镉含量为75 mg ／kg 时，初步试验和验证试验的稻槎菜地上部分镉含量分别为119．50，110．11 mg ／kg，均达到镉超富集植物的临界值（100 mg ／kg）。在土壤镉浓度大于0 mg ／kg的处理条件下，稻槎菜根系及地上部分富集系数（BCF）均大于1，转运系数（TF）也均大于1。稻槎菜根系、地上部分及整株镉积累量均随土壤镉浓度的增加而增加，并与土壤镉浓度存在极显著线性回归关系。验证试验表明，随土壤镉浓度的增加，稻槎菜叶绿素含量呈先降后增再降的趋势，SOD 活性呈先增后降的趋势，POD 活性呈先降后增的趋势，这与稻槎菜的特殊生理机制有关。小区试验研究表明，在土壤镉浓度为2．04～2．89 mg ／kg 时，稻槎菜地上部分镉积累量为1．10～1．13 mg ／m2。因此，稻槎菜是一种镉超富集植物，可用于镉污染稻田的冬季修复。