Effects of Hg and Pb Stress on Seed Germination of Trifolium repens L.

摘要

Trifolium repens L.served as the experimental subject to investigate the effects of varying concentrations of Hg andPb stress on seed germination,thereby providing a theoretical foundation for further research on the remediation of heavy-metal-contaminated soil utilizing this species.The findings indicated that the germination energy,germination percentage and germinationindex under 10 mg·L^-1 Hg treatment were significantly elevated compared to the CK group （P<0.05）,with a remarkable germination percentage reaching 97%.Conversely,the germination energy,germination percentage,germination index,vigor index,radicle length,and fresh weight under 200 mg·L^-1 Hg treatment were substantially lower than those of the CK group （P<0.05）.At 100 mg·L^-1 Pb treatment,the radicle length of Trifolium repens L.was significantly higher than that of the CK group,whereas the 500 mg·L^-1 Pb treatment resulted in a notable reduction in seed germination energy,germination percentage,germination index,and vigor indexcompared to the CK group （P<0.05）.Under Hg and Pb stress,the activities of superoxide dismutase （SOD） and peroxidase （POD） initially increased before declining,while catalase （CAT） activity rose with increasing heavy metal concentrations.Ultrastructure observations of the radicle revealed that 200 mg·L^-1 Hg inflicted considerable damage to the radicle of Trifolium repens L.,and 500 mg·L^-1 Pb also harmed root cells,resulting in the dissolution of nucleoli within the nuclear membrane.The results demonstrated that low concentrations of heavy metal also promoted the germination of Trifolium repens L.,while both 200 mg·L^-1 Hg and500 mg·L^-1 Pb significantly inhibited its germination.

关键词

Trifolium repens L. / heavy metal / seed germination / seedling growth