铅、镉对南荻种子萌发和幼苗生长的影响

Effects of Pb and Cd on the Seed Germination and Seedling Growth of Triarrhena lutarioriparia

以中国特有的非粮能源植物——南荻(Triarrhena lutarioriparia)为试验材料,采用水培法研究重金属铅(5、10、20、50、80 mg·L^(-1))、镉(0.5、1、5、10、20 mg·L^(-1))对南荻种子萌发和幼苗生长的影响,旨在为植物修复重金属污染土壤提供一定的依据。结果表明,南荻种子的发芽率、发芽势、发芽指数和活力指数均与铅、镉处理质量浓度呈极显著负相关(P<0.01),铅处理质量浓度(≤50 mg·L^(-1))显著增加异常发芽率(P<0.05)。铅对南荻根长抑制作用显著(P<0.05),当铅质量浓度达到10 mg·L^(-1)时,芽伸长开始受到抑制;镉胁迫对南荻种子根和芽的生长均表现为低浓度促进、高浓度抑制的作用,镉质量浓度为0.5、1 mg·L^(-1)时,南荻根长较对照分别增加18.8%、10.8%,当镉质量浓度≥5 mg·L^(-1)时,根长抑制率与芽长抑制率均显著增大(P<0.05)。铅、镉处理对南荻种子根长的抑制作用大于对芽长的抑制作用。回归分析表明,南荻铅胁迫下种子萌发和幼苗生长的临界浓度和极限浓度分别大于镉胁迫对应的浓度,说明南荻种子对铅的耐性强于镉。铅、镉对南荻种子的毒害作用不可逆。

In order to provide a reference for phytoremediation of heavy metal contaminated soil,the effects of Pb(5,10,20,50,80 mg·L-1)and Cd(0.5,1,5,10,20 mg·L-1)on the seed germination and seedling growth of T.lutarioriparia,a native non-food energy plant in China,were studied,using water culture method.The results showed that there were strongly negative correlations(P<0.01)between the concentrations of Pb and Cd and the germination rate,germination potential,germination index and vital index of T.lutarioriparia.Meanwhile,the seed abnormal germination was significantly promoted(P<0.05)by Pb stress(≤50 mg·L-1).While the inhibition rate of root length was notably increased(P<0.05)with the increase of the concentration of Pb,the shoot length was suppressed from the concentration of Pb reached 10 mg·L-1.Moreover,the results revealed that the length of root and shoot increased at lower Cd concentration,while decreased at higher concentration.Under the Cd concentrations of 0.5 and 1 mg·L-1,compared with the control the length of root increased by 18.8%,10.8%,respectively,while the shoot length showed no significant difference with control.Furthermore,the inhibition rates of root and shoot length was remarkably increased(P<0.05)once the concentration of Cd exceeded 5 mg·L-1.In addition,it could be found that the inhibiting effect of Pb and Cd on root growth was stronger than that on shoot growth.Regression analysis indicated that the critical concentration and limit concentration of seed germination and seedling growth of Pb stress were greater than those corresponding to Cd stress,which proved that T.lutarioriparia showed stronger tolearance to Pb than Cd.Lastly,the results also demonstrated that the toxic effects of Pb and Cd on the seed of T.lutarioriparia were irreversible.