不同磷效率小麦品种对镉、铅吸收和积累的差异分析

Differential Analysis in the Uptake and Accumulation of Cadmium and Lead by Wheat Varieties with Different Phosphorus Efficiencies

【目的】明确不同磷效率小麦品种对磷(P)、镉(Cd)和铅(Pb)吸收、转运和积累的差异及其相互关系。【方法】室内培养下,开展不同物质的量浓度的P、Cd、Pb单因素试验,分析不同磷效率小麦品种对P、Cd和Pb的吸收、转运特性及其相互关系;大田环境条件下,在Cd、Pb中度污染区进行随机区组试验,验证不同磷效率小麦品种对P、Cd和Pb的积累差异。【结果】磷高效小麦品种(HP)根系的平均含P量为7.69 mg/g,显著低于磷低效品种(LP)的8.36 mg/g(P<0.05),而HP品种地上部的平均含P量为9.73 mg/g,显著高于LP的8.19 mg/g(P<0.05),同时HP品种的P转运系数为1.45,显著高于LP品种的1.19(P<0.05)。不同磷效率小麦根系和地上部对Cd和Pb吸收动力学特征都符合米氏方程(R^(2)>0.94),其最大吸收速率(V_(max))和米氏常数(K;)在HP和LP品种间存在显著差异(P<0.05)。HP品种根系对Cd、Pb的V_(max)分别为23.9μg/(g·d)和411μg/(g·d),极显著低于LP品种的80.0μg/(g·d)和835μg/(g·d)(P<0.01),而HP品种地上部对Cd、Pb的V_(max)最大,LP品种的V_(max)最小,并且K_(m)在HP和LP品种间的差异与V_(max)相一致。相关性分析表明,Cd和Pb转运系数与根系含磷量均呈极显著负相关(r分别为-0.638和-0.714,P<0.01),而Cd转运系数与P转运系数呈极显著正相关(r=0.671,P<0.01),Pb转运系数与P转运系数无显著相关性(r=0.391,P>0.05),说明根系含P量的增加有助于降低Cd、Pb向地上部的转运,同时,P转运的增加不能有效增加Pb向地上部的转运,却能显著促进Cd的转运。【结论】磷低效品种根系对P、Cd和Pb的吸收量大,但转运量小;而磷高效品种对P、Cd和Pb的吸收量少,但转运量大,表明Cd、Pb安全利用类土壤更适宜种植磷低效小麦品种。

【Objective】Soil contamination by cadmium (Cd) and lead (Pb) is a great environmental concern for food safety,and breeding cultivars that can reduce their uptake is one way to grow crops in Cd-and Pb-contaminated soils.In this paper,we experimentally studied how wheat lines with different phosphorus (P) uptake affect their uptake,translocation and accumulation of P,Cd and Pb in the crops.【Method】The experiment consisted of a lab part and a field part.The lab part considered one factor–wheat varieties,and the field part was arranged randomly in soil that had been moderately contaminated by Cd and Pb.In both parts,we measured Cd and Pb uptake and their subsequent translocation.【Result】The average P content in the roots of lines with high P (HP) use efficiency was 7.69 mg/g,significantly lower than that in the lines with low P (LP) use efficiency,which was 8.36 mg/g (P<0.05).The average P content in the shoots of HP varieties was 9.73 mg/g,significantly higher than the 8.19 mg/g in the LP cultivars (P<0.05).The transport coefficient of P in HP varieties was 1.45,significantly higher than the 1.19 of the LP varieties (P<0.05).The kinetic uptake of Cd and Pb by roots and their translocation to shoots followed MichaelisMenten equation (R^(2)>0.94),with the maximum absorption rates (V_(max)) and the Michaelis constants (K_(m)) differing significantly between varieties (P<0.05).The V;of the roots of HP varieties was 23.9 and 411μg/(g·d),respectively,for Cd and Pb,in comparison with 80.0 and 835μg/(g·d)(P<0.01) for the LP lines.In contrast,V_(max)for Cd and Pb in the shoots of the HP varieties was much higher than that for the LP varieties.The difference in K;between the HP and LP varieties was consistent with their difference in V_(max).Correlation analysis showed that the transport coefficients of both Cd and Pb were negatively correlated with root P content (r=-0.638 and-0.714,respectively) at significant level.The transport coefficient of Cd was positively correlated with P transport coefficient (r=0.671,P<0.01).The Pb transport coefficient was also positively correlated with P transport coefficient though not at significant level (r=0.391,P>0.05).The increase in root P content helps reduce the translocation of Cd and Pb;an increase in translocation coefficient of P did not show a noticeable impact on Pb translocation,but significantly boosted Cd transport from roots to the shoots.【Conclusion】The roots of LP varieties showed high uptake but low translocation of P,Cd and Pb,as opposed the HP varieties which showed a low uptake but high translocation.This suggests that LP varieties are more suitable for growing in soils contaminated by Cd and/or Pb.