JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2021, Vol. 45 ›› Issue (3): 61-70.doi: 10.12302/j.issn.1000-2006.202103020

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A comparative study on lead tolerance and accumulation of seven poplar species

SHI Wenguang1(), LI Jing2, ZHANG Yuhong1,3, LEI Jingpin1, LUO Zhibin1,*()   

  1. 1. State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Silviculture of National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
    2. College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China
    3. Berry Oncology Technology Co., Ltd., Beijing 100102, China
  • Received:2021-03-09 Revised:2021-04-06 Online:2021-05-30 Published:2021-05-31
  • Contact: LUO Zhibin E-mail:swg0911@126.com;luozbbill@163.com

Abstract:

【Objective】In this study, we aimed to find the promising poplar species for the remediation of lead (Pb)-contaminated soil by comparing the lead (Pb) resistance and accumulation of different poplar species. 【Method】Seven fast-growing poplar species were exposed to 8 mmol/L Pb(NO3)2 for 6 weeks to analyze their capacities for Pb tolerance and accumulation. 【Result】The net photosynthetic rate, stomatal conductance and transpiration rate were significantly reduced in the leaves of Pb-exposed poplar plants compared to those under the controlled condition. Thus, the axial and radial growth of poplar plants were inhibited by Pb exposure. The photosynthesis and growth of Populus nigra, P. × popularis and P. cathayana were more sensitive, and those of P. deltoides were less sensitive to Pb exposure than the other poplar species. The biomass of Pb-treated poplar plants was declined in comparison with that of poplar plants under the controlled condition. The greatest reduction in root biomass was found in P. × euramericana (50.31%); the significant decreases in wood biomass were found in P. nigra (31.99%) and P. × popularis (22.26%); the significant decreases in bark biomass were found in P. × euramericana (12.67%) and P. × popularis (19.54%); the greatest reduction in leaf biomass was found in P. × canescens (35.44%). The total biomass of the seven poplar species decreased significantly under Pb stress. The largest decrease was found in P. × canescens (29.03%), and the smallest reduction was found in P. nigra (12.02%). Correspondingly, the tolerance index of the seven poplar species was decreased in the order: P. nigra (88.09%) > P. alba × P. glandulosa (82.98%) ≈ P. deltoides (80.70%) > P. × euramericana (79.86%) > P. cathayana (76.79%) > P. × popularis (72.78%) ≈ P. × canescens (70.35%). Significant differences in absorption and transport of Pb were found among poplar species. P. deltoides displayed the highest Pb concentration in the roots (2 906.10 mg/kg). P. × canescens showed the highest concentrations of Pb in the wood (46.55 mg/kg), bark (44.39 mg/kg) and leaves (325.90 mg/kg). The total Pb amount in the roots (4.20 mg/plant) and whole plant (5.06 mg/plant) of P. deltoides and those in the aerial part (1.21 mg/plant) of P. × canescens were the largest among the seven poplar species. P. deltoides showed the highest bio-concentration factor of roots (6.70) and P. × canescens displayed the highest bio-concentration factor of the aboveground tissue (0.43). Meanwhile, P. × canescens displayed the highest translocation factor (0.16), and P. nigra showed the lowest translocation factor (0.02). 【Conclusion】Significant differences in Pb tolerance and accumulation were found among the seven poplar species. Among which, P. nigra and P. deltoides displayed the strongest abilities for Pb tolerance and absorption, respectively, and thus both species may have great potentials for phytostabilization and ecological restoration of Pb-polluted soil. P. × canescens showed the strongest ability to transport Pb to the aboveground tissues, and thus it may have a great potential for phytoextraction of Pb in contaminated soil.

Key words: Populus spp., phytoremediation, Pb stress, photosynthesis, biomass, Pb accumulation, soil heavy metal pollution

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