土壤铅-苯并[a]芘复合污染对小麦种子生长的影响研究

Effects of Combined Pollution of Lead and Benzo[a]pyrene on Seed Growth of Wheat in Soils

研究了土壤中低含量铅(Pb)-苯并[a]芘(B[a]P)复合污染对小麦种子萌发率、根伸长、芽伸长以及芽根比的影响,以期考察复合污染的生态效应并筛选具有指示土壤污染程度的指标.结果表明,小麦种子萌发率对Pb-B[a]P单一及复合污染均不敏感;Pb和B[a]P单一污染时小麦根伸长均受到一定程度的抑制作用;复合污染条件下Pb-B[a]P间发生明显的交互作用,一方面Pb和B[a]P对小麦根伸长具有协同刺激作用,另一方面Pb削弱B[a]P对小麦根伸长的抑制作用,联合作用以拮抗效应为主.B[a]P单一污染对小麦芽伸长有一定的抑制作用.复合污染条件下,小麦芽伸长与Pb含量间有极显著的正相关性(p<0.01),B[a]P及Pb-B[a]P间的交互作用对芽伸长的影响较弱,联合作用的结果均表现为拮抗效应.小麦芽根比的响应规律与芽的响应规律类似,但芽根比与Pb含量间的相关性更显著,更适合于指示土壤Pb污染程度.当Pb以乙酸铅形式投加时,根伸长受到的刺激作用被进一步增强,芽伸长受到的刺激作用被削弱,而芽根比受到的刺激作用则被消除.Pb投加形式对小麦种子生长有显著的影响.

Seed germination,root elongation,shoot elongation and ratio of shoot to root of wheat in soils polluted by lead（Pb） and benzo（a）pyrene（B[a]P） with medium-low concentrations were studied to reveal the ecological effects of combined pollution and screen the indicative markers.Results indicated that seed germination was not sensitive to single or combined pollution of Pb or B[a]P.Root elongation was inhibited by single pollution of Pb or B[a]P to different extents.Extensive interactions between Pb and B[a]P occurred to root elongation of wheat,including synergistic-stimulatory effect and antagonistic-inhibitory effect.The joint action was mainly antagonistic.Single pollution of B[a]P had an inhibitory effect on shoot elongation.Under combined pollution conditions,the shoot elongation of wheat correlated well with Pb contents（p 0.01）.B[a]P or the interactions between pollutants had little effect on shoot elongation of wheat.The joint action on shoot elongation was consistently antagonistic.The response pattern of the ratio of shoot to root was similar to the response pattern of shoot elongation.However,the former had better correlation than the latter,indicating it as a more suitable indicative marker for Pb pollution.If lead acetate was employed instead of lead nitrate,longer root elongation,shorter shoot elongation and no effect on ratio of shoot to root were found.Therefore,the forms of Pb salt had significant influence on seed growth of wheat in soils.