3种螯合剂对铅胁迫下香樟幼苗生长及铅富集的影响

为了研究在添加不同螯合剂的情况下,植物对土壤Pb(铅)胁迫的生理生长反应及对Pb的富集转运情况,揭示其变化机制,筛选出较好的螯合剂及适宜的质量摩尔浓度,选择香樟幼苗为试验对象,在Pb质量分数为1045 mg·kg^-1土壤中分别添加柠檬酸、苹果酸和乙二胺四乙酸(EDTA)3种螯合剂,每种螯合剂分别设置了0、2、4、6、8 mmol·kg^-15个质量摩尔浓度,测量香樟幼苗的生长指标、生理指标以及Pb富集转运等指标并进行统计分析。结果表明:3种螯合剂对香樟幼苗生长生理及Pb的富集转运均有显著影响,随着3种螯合剂质量摩尔浓度的增加,Pb胁迫加重;同一质量摩尔浓度下,多数指标,经EDTA处理的分别与经柠檬酸和苹果酸处理的结果有显著差异,柠檬酸和苹果酸处理二者之间差异不显著;EDTA质量摩尔浓度不大于2 mmol·kg^-1,柠檬酸、苹果酸质量摩尔浓度不大于4 mmol·kg^-1,香樟生长状况及Pb吸收综合效果最好。综合分析得出:柠檬酸、苹果酸、EDTA都具有促进植物吸收土壤Pb的作用,3种螯合剂均能提高香樟幼苗的富集系数和转移系数;当土壤Pb质量分数为1045 mg·kg^-1、EDTA质量摩尔浓度为2 mmol·kg^-1、柠檬酸和苹果酸质量摩尔浓度为4 mmol·kg^-1时,香樟幼苗吸收土壤Pb的效果最佳。在达到同等效率的前提下,建议优先选用柠檬酸或苹果酸为宜。

Effect of Three Chelating Agents on Plant Growth and Lead Accumulation of Camphor Seedlings under Lead Stress

To study the response of the physiological growth and the enrichment and the transport of lead under different chelating agents, a camphor seedling experiment were designed to reveal the mechanism and screen out the appropriate chelating agents and concentrations. Three chelating agents including citric acid, malic acid and EDTA were added to the soil with the lead content of 1 045 mg·kg^-1. Five concentrations(0, 2, 4, 6 and 8 mmol·kg^-1) were set for each chelating agent. The growth index, physiological index and Pb enrichment and transportation index of seedlings were measured and analyzed. Three chelating agents had significant effects on the growth physiology and the accumulation and the transportation of Pb in camphor seedlings. With the increase of the concentration of three chelating agents, the stress of Pb was aggravated. At the same concentration, the most indices of EDTA treatment were significantly different from those of the citric acid and the malic acid treatment, but there was no significant difference between the citric acid and the malic acid treatment. When the concentration of the EDTA was not more than 2 mmol·kg^-1 and those of the citric acid and the malic acid was less than 4 mmol·kg^-1, the comprehensive effects of camphor growth and Pb absorption were the best. Comprehensive analysis showed that the citric acid, the malic acid and the EDTA all could promote plant to absorb soil Pb, and improve the seedlings’ enrichment coefficient and the transfer coefficient. When the soil Pb concentration were all 1 045 mg·kg^-1, the EDTA concentration was 2 mmol·kg^-1, the citric acid and the malic acid concentration was 4 mmol·kg^-1, and camphor seedlings had the best absorption on soil Pb. Therefore, the citric acid or the malic acid will be a priority under the same efficiency premise.