Study On Growth Physiological Response And Enrichment Of Populus Simonii × P.nigra And P.euramericana ’N3016’ × P.ussuriensis To Lead-Zinc Stress

In order to investigate the tolerance of different species of poplars to Pb²⁺,Zn²⁺ stresses,and to Provide phytoremediation materials for remediation of Pb²⁺ and Zn²⁺ pollution in soil.the annual P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis were studied by and potted cutting seedling.To explore the effect of growth traits,biomass,osmotic regulation substances response,antioxidant enzyme activity,correlation analysis,and the enrichment and transfer of P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis on the stress of Pb²⁺ and Zn²⁺.The results are as follows:（1）The seedling height and ground diameter of P.simonii × P.nigra and P.euramericana‘N3016’ × P.ussuriensis were not significantly increased and the biomass accumulation reached a significant increase compared with the control at low concentrations of single stress(Pb²⁺<100 mg·L-1 and Zn²⁺<200 mg·L-1),and the largest biomass of roots,stems and leaves of P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis were at the concentrations of Pb²⁺<100 mg·L-1,the highest biomass of the roots,stems and leaves of P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis were at the concentrations of Zn²⁺<200 mg·L-1.When the single concentrations stress of Pb²⁺ above 100 mg·L-1 and the concentrations of Zn²⁺ higher than 200 mg·L-1,with the increase of Pb²⁺ and Zn²⁺ stress concentration,the growth and biomass of P.simonii × P.nigra and P.euramericana ’N3016’ ×P.ussuriensis were inhibited more seriously.The combined stress of Pb²⁺ and Zn²⁺ showed a co-inhibitory effect on the growth traits of P.simonii × P.nigra and P.euramericana ’N3016’ ×P.ussuriensis,The correlation between the height of P.simonii × P.nigra seedlings with Pb²⁺and Pb²⁺/Zn²⁺ stress was extremely significant(R2Pb²⁺=0.759**.R2Pb²⁺+Zn²⁺=0.810**),ground diameter and biomass with Zn²⁺stress was significant（R2地径=-0.666*,R2 生物量=-0.666*）,while the growth traits of P.euramericana ’N3016’ × P.ussuriensis were not significantly correlated.（2）The contents of chlorophyll a and total chlorophyll of P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis showed a trend of first increase and then decrease with the increase of Pb²⁺ and Zn²⁺ stress concentrations,and the change trend of chlorophyll b was not obvious,and the photosynthesis inhibition degree under single stress was lower than compound stress.Pb²⁺ and Zn²⁺ stress had the effect of "low Promotion and high inhibition" on the content of soluble sugar,soluble Protein,and the enzyme activities of SOD,POD and CAT in P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis,the contents of Proline and malondialdehyde increased with the increase of Pb²⁺ and Zn²⁺ stress concentration.Pro of P.simonii × P.nigra and P.euramericana ’N3016’×P.ussuriensis increased 65.79%～361.84%and 25.91%～157.56%under Pb²⁺ stress,39.47%～300.99%and 49.72%～219.19%under Zn²⁺stress,108.55%～399.67%and 38.52%～197.48%under compound stress.MDA increased by 12.91%～52.98%and 12.89%～79.44%under Pb²⁺ stress,-12.58%～53.97%and 4.18%～81.18%under Zn²⁺stress,and 10.93%～53.97%and 16.72%～89.20%under compound stress.The correlation between the soluble Protein,soluble sugar,Proline,MDA,SOD and Pb²⁺ and Zn²⁺ stress of P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis was extremely significant.（3）The accumulation of Pb²⁺ in organs of P.simouii × P.nigra and P.euramericana’N3016’ × P.ussuriensis was as follows:root>stem>leaf.The accumulation of Pb²⁺ in roots of P.simonii × P.nigra was 6.38～21.11 times of stem and 7.59～70.88 times of leaf,and 10.25～17.87 times of stem and 11.56～38.83 times of leaf in the root of P.euramericana’N3016’ × P.ussuriensis.The accumulation of Pb²⁺ in organs of P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis under compound stress was less than that under Pb²⁺stress,and Zn²⁺ hindered the accumulation of Pb²⁺ in roots.The distribution of Zn²⁺ in organs of P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis was as follows:leaf>root>stem.Under compound stress,the concentration of Zn²⁺ in P.simouii × P.nigra leaves decreased by 233.95～884.74 mg·kg-1 compared with the corresponding Zn²⁺ stress,and that in P.euramericana ’N3016’ × P.ussuriensis decreased by 252.59～617.78 mg·kg-1.Pb²⁺ inhibited the enrichment of Zn²⁺ in roots,stems and leaves of P.simouii × P.nigra and P.euramericana’N3016’ × P.ussuriensis.The transfer capacity of Pb²⁺ and Zn²⁺ under single stress was stronger than that of compound stress.Pb²⁺ and Zn²⁺ showed antagonistic effects in the transfer Process of organs of P.simonii × P.nigra and P.euramericana ’N3016’ × P.ussuriensis.