镧对镉胁迫下大蒜幼苗生长及镉积累的影响

采用土培实验研究了镧(La²⁺)对镉(Cd)胁迫下大蒜幼苗生长及Cd积累的影响。结果表明：低浓度Cd（＜5 mg·kg^-1）对大蒜生长有微弱的促进作用而高浓度Cd对其有明显抑制作用。外施系列浓度La²⁺对高浓度Cd胁迫下大蒜幼苗生长具有明显的缓解效应，单株鲜重、干重、根长及地上部分高度均具有明显或不同程度的增加。测定结果表明，Cd主要积累在大蒜根部而向地上部分转运的较少，外施系列浓度La²⁺对高浓度Cd胁迫下大蒜幼苗根系对Cd积累具有显著的抑制效应，同时也抑制Cd向地上部分转运。从外施La²⁺对高浓度Cd胁迫下大蒜幼苗生长及大蒜对Cd积累情况来看，La²⁺的适宜缓解效应浓度是在Cd浓度为20 mg·kg^-1时，La²⁺浓度为10～15 mg·kg^-1；在Cd浓度为40 mg·kg^-1，La²⁺浓度为5 mg·kg^-1。

Effect of La2+ on the Growth of Allium sativum L. and Cadmium Accumulation under Cd Stress

The effects of La²⁺ on the growth of Allium sativum L. and Cadmium(Cd) accumulation under Cd stress were studied in the present paper by soil cultivation experiments. The results showed that the seedlings growth of A. sativum L. could be promoted a little under low concentration of Cd（＜5 mg·kg^-1）, while the seedlings growth could be obviously inhibited under high concentration of Cd. When La²⁺(concentration range from 5 to 20 mg·kg^-1) was exerted on A. sativum L. seedlings under high concentration Cd stress one time, the growth of seedlings was obviously reconditioned, Their average fresh or dry weight and the average length of roots, overground height significantly increased to some certain degree. Assay results also showed the roots of A. sativum L. absorbed large amounts of Cd, the Cd accumulated mainly in the roots and small amounts of Cd were translocated to the leaves. Accumulation of Cd of seedlings roots and translocation of Cd to overground part were obviously inhibited when La²⁺ was exerted on A. sativum L. seedlings. According to the growth of A. sativum L. and Cd accumulation of seedlings under high concentration Cd stress when La²⁺ was exerted on seedlings, valid concentration of La²⁺ was respectively 10～15 mg·kg^-1 or 5 mg·kg^-1 when Cd stress concentration was 20 or 40 mg·kg^-1.