镉胁迫对秋华柳根系活力及其Ca、Mg、Mn、Zn、Fe积累的影响

以秋华柳为试验材料,采用水培试验方式,设置CK(0 mg·L^-1 Cd²⁺)、T₁(2 mg·L^-1 Cd²⁺)、T₂(10 mg·L^-1Cd²⁺)、T₃(20 mg·L^-1Cd²⁺)、T₄(50 mg·L^-1Cd²⁺)5种镉处理浓度,通过对秋华柳根系活力,叶、韧皮部、木质部和根部的镉含量,以及Ca、Mg、Mn、Zn、Fe 5种常规金属元素含量的测定,研究了不同浓度镉胁迫下秋华柳根系活力及Ca、Mg、Mn、Zn、Fe 等金属元素含量的变化.结果表明:1)秋华柳根系活力随着镉处理浓度的增加而逐渐下降,当镉浓度≥10 mg·L^-1时,根系活力与对照相比显著下降.2)随着镉处理浓度的增加,秋华柳叶中Fe的积累受到显著抑制;韧皮部Mg、Mn、Fe的积累受到显著抑制;木质部Ca、Mg、Mn、Zn、Fe 等5种常规金属元素的积累无显著性差异;根部5种常规金属元素的吸收和积累受到显著抑制,表现出镉对其他金属元素积累的拮抗作用.其中,50 mg·L^-1的镉胁迫下,根部Zn的积累量降幅最大,受Cd的抑制最明显.3)各处理组Fe的转移系数与对照相比均无显著性差异;Ca、Mg、Mn、Zn的转移系数均高于对照,且在一定的镉处理水平上差异显著.4)镉胁迫下,秋华柳根部镉的积累量与Ca的积累量呈显著负相关,与其他4种常规金属元素的积累量呈极显著负相关,说明根部常规金属元素的变化可作为秋华柳受镉毒害程度的指示之一.

Effect of cadmium stress on root vigor and accumulation of elements Ca,Mg, Mn,Zn, Fe in Salix variegate.

In order to explore the effect of cadmium stress on root vigor and accumulation of five kinds of conventional metal elements in Salix variegata, a hydroponic experiment with different cadmium treatments were conducted. The cadmium treatments included 0 mg·L^-1 (CK), 2 mg·L^-1 (T₁), 10 mg·L^-1 (T₂), 20 mg·L^-1 (T₃) and 50 mg·L^-1 (T₄). The root vigor and distribution of cadmium and five kinds of conventional metal elements (including Ca, Mg, Mn, Zn and Fe) in S. variegata were tested. The results showed that: 1) The root vigor of S. variegata decreased with increasing cadmium stress gradually. Compared to control, the root vigor decreased significantly in treatments with the cadmium concentration reaching and exceeding 10 mg·L^-1. 2) With increasing the cadmium concentration, the abilities of S. variegata to absorb and accumulate Fe in leaves were inhibited significantly; the abilities to absorb and accumulate Mg, Mn and Fe in phloem were inhi-bited significantly; the abilities to absorb and accumulate Ca, Mg, Mn, Zn and Fe in xylem had no significant differences; and the abilities to absorb and accumulate Ca, Mg, Mn, Zn and Fe in root were inhibited significantly. It could be concluded that cadmium had antagonistic effect on the accumulation of the other metal elements, especially Zn in plant root. 3) With increasing concentrations of cadmium, the translocation factors of Ca, Mg, Mn and Zn increased significantly when compared to control, while there was no significant influence on Fe. 4) Under cadmium stress, there was a significantly negative correlation between the accumulations of cadmium and Ca in S. variegate root, and a very significantly negative correlation between the accumulations of cadmium and the other four kinds of conventional metal elements, indicating that the change of conventional metal elements in S. variegate root could be one of the indices of the degree of cadmium stress.