Effects of Pb stress on C, N and P accumulation and allocation in Populus deltoids × P. nigra seedlings
铅胁迫对欧美杂交杨幼苗碳、氮和磷积累与分配的影响

Aims Little information has been available on the effects of soil Pb pollution on plant nutrition. Our objective was to characterize the responses of poplar (Populus deltoids × P. nigra) in C, N and P accumulation and N and P use efficiency under different Pb stresses in acidic purple soil and alkaline purple soil. Methods A controlled pot experiment using one-year old poplar was arranged with different treatments of four Pb concentrations (CK: 0, T1: 200, T2: 450 and T3: 2 000 mg·kg–1) in the field. Concentrations of C, N and P in plant components were measured over one growing season. We calculated C, N and P accumulation and N and P use efficiency. Important findings Accumulations of C, N and P in poplar declined with increased Pb supplies in both acidic purple soil and alkaline purple soil. Accumulations of C, N and P in alkaline purple soil were larger than in acidic purple soil. Distribution patterns of C, N and P in poplar were altered in both soils when supplied with different Pb concentrations. C, N and P accumulation in fine roots significantly increased with increased Pb supplies in acidic purple soil, but decreased in fallen leaves. In contrast, C, N and P accumulation in fine roots decreased with increased Pb supplies in alkaline purple soil, but increased in fallen leaves. In addition, P use efficiency of the poplar in both soils increased with increased Pb supplies, but the N use efficiency significantly decreased under treatments T2 and T3. Results indicated that the accumulation of C, N and P in poplar had been inhibited and nutrient use efficiency of the plant had been altered by Pb stress. Moreover, the effects of Pb stress on nutrient accumulation, distribution and utilization by poplar were much less in alkaline soil compared to acidic soil.