异质Pb胁迫对超富集植物金丝草根系生长及生物量分配的影响

以Pb超富集植物金丝草（Pogonatherumcrinitum）为试验材料，设置不同Pb浓度的土壤异质胁迫室内模拟试验，定量测定不同Pb胁迫浓度和斑块中金丝草的根长、体积、表面积、平均直径等形态指标，以及根系和地上部分的生物量，比较不同异质Pb胁迫下金丝草根系形态指标及生物量分配的差异。结果表明，异质Pb胁迫对金丝草根长、根体积、表面积影响较明显，但对根平均直径的影响较小；随Pb胁迫浓度的增加，金丝草在Pb胁迫斑块和无Pb斑块的根长、根体积和表面积均呈逐渐增大的趋势，但无Ph斑块均大于Pb胁迫斑块；无Pb左室、Pb胁迫右室及整株根冠比均随Pb胁迫浓度的增加表现为先增大后减小的变化规律，表明轻度Pb胁迫条件下金丝草根系生物量分配较多，但随Pb胁迫浓度的增大，地上部的生物量所占比例逐渐增大。

Effects of Heterogeneous Pb Stress on Root Growth and Biomass Allocation of Pogonatherum crinitum

Heavy metals usually distribute heterogeneously in the real environment. A controlled glasshouse experiment was conducted to ex- plore the effects of heterogeneous Pb stress on root growth and biomass allocation of Pogonatherttm crinitum, a Pb hyperaccumulator first found by our research group. There were 6 heterogeneous Pb stress treatments with 5 replicates. The root length, root volume, root surface area, average root diameter and plant biomass were examined. Root length, root volume and root surface area but not root diameter were sig- nificantly influenced by Pb stress. The root length, root volume and surface area of Pogonatherum crinitum increased gradually with Pb con- centrations in both Pb stress and no lab patches, with greater increases in the later than in the former. The root-shoot ratio initially increased and then decreased as Pb concentrations increased, indicating that Pogonatherum crinitttm allocated more biomass to the roots under low Pb stress, but more to the shoots under high Pb stress.