Pb胁迫对红椿（Toona ciliata Roem）生长发育及Pb富集特性的影响

采用盆栽试验研究了酸性紫色土、钙质紫色土和冲积土上生长的一年生红椿实生苗暴露在不同浓度Pb胁迫（0、200、450mg·kg-1和2000mg·kg-1）条件下的叶长、叶面积、生物量、各器官Pb含量特征和富集程度,并分析了红椿对Pb污染的耐性和转移效率。3种土壤下红椿都能生长,但相同浓度Pb胁迫下其在钙质紫色土中生长状况最佳,在冲积土中生长状况最差。随Pb浓度增大红椿叶片生长受到明显抑制,当土壤中Pb浓度在2000mg·kg-1时,其叶长和叶面积与对照差异极显著（P〈0.01）;Pb胁迫使得红椿根茎比发生明显的变化,还加大其叶的凋落程度,同时整株生物量随着Pb胁迫浓度的增大呈极显著降低趋势（P〈0.01）,但在土壤Pb浓度最大时其生物量仍达到对照的81.47%以上。红椿体内Pb含量与土壤Pb浓度成正相关（P〈0.01）,其6个器官中细根Pb含量最高,粗根次之,而地上部分的Pb含量较低且差异不大。红椿耐性指数值在0.67~1.06之间,表现为随Pb胁迫浓度增大,其耐性呈下降趋势。红椿富集系数与转移系数都较小且小于0.3。这些结果表明,红椿能在Pb污染较严重的土壤中较好的生存,可作为Pb污染区域潜在的土壤修复树种。

Effects of Pb Stress on the Growth, Development and Pb Enrichment Properties of Toona ciliata Roem Saplings

To character the growth and Pb enrichment properties of Toona ciliata under Pb polluted soils, leaf length, leaf area, biomass, and Pb concentration in organs of one-year-old T. ciliota samplings were investigated under different Pb treatments（0 mg·kg-1, 200mg·kg-1, 450 mg·kg-1 and 2 000 mg-kg-1） in acid purple soil, alkaline purple soil and alluvial soil in western Sichuan, China. T. ciliate showed good growth characteristics in three soil types, especially in alkaline purple soils. Increased Pb stress obviously inhibited leaf growth regardless of soil substrate. The highest Pb stress （2 000 mg·kg-1） significantly （P〈0.01 ） reduced leaf length and area in comparison with control. Pb stress obviously changed the root/shoot ratio of the samplings and increased leaf litters. The total biomass was decreased significantly（P〈0.01 ） with the increase of Pb stress but the biomass in the highest Pb stress only decreased to 81.47% of the biomass in control. Pb concentration in T. ciliate samplings was positively（P〈0.01 ） related to Pb concentration in soil. Compared with other organs, fine roots displayed the high- est Pb concentration. Few obvious variations of Pb concentration were observed among leaf, shoot, petiole and litter. The Pb tolerance indices of T. ciliate samplings were from 0.67 to 1.06 depending on Pb stress and soil substrates. The tolerance index decreased with the increase of Pb stress. The enrichment and transfer efficiencies were lower than 0.3. The results revealed that T. ciliate could have a good growth in the soils with severe Pb pollution, wieh could be a potential tree specie for Pb phytoremediation in western Sichuan.