镉和温度预暴露对小麦吸收镉的影响

Uptake of Cadmium by Wheat(Triticum aestivum) as Affected by Pre-Exposure to Cadmium and Temperature

土壤中重金属Cd污染是一个累积过程,污染历史会影响植物对土壤中Cd的吸收.近年来,随着全球气候的变暖,温度对Cd的生物有效性的影响日益引起关注.通过模拟土壤溶液,研究了Cd的浓度、温度和预暴露时间对小麦吸收Cd的影响.小麦在浓度为0.01和0.1μmol·L-1的Cd中经过不同时间的预暴露后进行6h的短期吸收实验.结果发现,经1d预暴露后,小麦根部吸收Cd的量有增加趋势,这说明Cd对小麦产生了刺激作用,小麦地上部分的含Cd量也有所增加但不显著.经5d预暴露后,小麦对Cd产生了抗性,这使得小麦根部降低了对Cd的吸收量;并且当Cd为0.1μmol·L-1时,根部Cd吸收量的降低最为明显;由于Cd从根部向地上部迁移是一个复杂的生理过程,预暴露对地上部分Cd含量的影响没有根具有规律性;经过37℃高温胁迫4h后,小麦根部及地上部分的Cd含量减少高达40%;预暴露和高温共同作用后,其减少量更多,这说明预暴露和高温共同作用能够减少小麦对Cd的吸收量.

As global temperature rising and soil Cd pollution growing,more attention has been paid to studying the influences of temperature and pollution history on Cd bioavailability.In this paper,the simulated soil solution was applied in the short term（6h） uptake experiment to study the effects of factors on the Cd bioavailability to wheat.The time and Cd concentration of pre-exposure and exposure in Cd solution,and temperature of solution were considered responsible for the uptakes of Cd in wheat.The results indicated that the uptake of Cd increased with the increasing solution Cd concentration.Cadmium was mainly accumulated in the roots,and the translocation coefficients of Cd from root to shoot were only 10%.5d pre-exposure of the seedlings to 0.01μmol·L-1 Cd did not significantly affect the uptake of Cd in the roots.However,the uptake of Cd was significantly lower than the control after their pre-exposure to 0.1μmol·L-1 Cd,except exposing to 5.0μmol·L-1 Cd.When the wheat seedlings were exposed to 1.0 or 5.0μmol·L-1 Cd,the root Cd concentrations via pre-expose to 0.01 or 0.1μmol·L-1 Cd for one day were significantly higher than that of the controls.The pre-exposure to Cd did not regulate the uptake in the shoot as that in the root due to the movement of Cd from root to shoot is a complicated process.The heat stress at 37℃ for 4h could decrease the uptake of Cd in the roots and the shoots of wheat.