镉对不同生长期籽粒苋植物螯合肽的影响

植物螯合肽（PCs）由于其含有大量的巯基，能够螯合重金属离子，对重金属的积累和解毒起着重要作用.以镉（Cd）富集型植物籽粒苋K472为研究对象，采用土培法，设置6个Cd处理水平为：0（CK）、10（T1）、25（T2）、50（T3）、100（T4）和200 mg·kg^-1（T5），分析Cd胁迫下营养生长初期、中期和后期的K472植物螯合肽的变化特征，探究植物螯合肽对Cd的螯合解毒机制.结果表明，各生长阶段的K472的株高、根长、生物量随着Cd胁迫含量的升高而下降显著，其降幅随着K472生长发育逐渐降低.而营养生长中期的K472对Cd的富集能力最强，最大Cd富集量为6695.35 mg，最大富集系数为6.3.此外，随着Cd胁迫含量的增加，不同生长阶段的K472根、茎和叶内Cd含量与PCs含量呈显著正相关.其中，根系及茎部中对Cd胁迫响应最强的植物螯合肽为PC3，叶片中对Cd胁迫响应最强的植物螯合肽为PC2.实际应用中，在营养生长中期采收籽粒苋K472可获得更高的修复效率.

Effect of Cadmium Stress on Phytochelatins in Amaranthus hypochondriacus L. During Different Growth Periods

Phytochelatins (PCs) can chelate heavy metal ions due to their large number of thiols and play an important role in heavy metal accumulation and detoxification. A. hypochondriacus K472, a cadmium (Cd) enriched plant, was selected as the research object. Six Cd treatment concentrations, namely 0 (CK), 10 (T1), 25 (T2), 50 (T3), 100 (T4), and 200 mg ·kg^-1 (T5), were used to analyze the variation of PCs in different growth stages under different degrees of Cd stress and to explore the mechanism by which PCs chelate and detoxify Cd. The results showed that the plant height, root length, and biomass of K472 decreased significantly with increasing Cd concentration, and the range of decrease gradually became less pronounced with the growth and development of K472. K472 exhibited the maximum ability to enrich Cd during the middle vegetative growth period. The maximum concentration was 6695.35 mg, and the maximum bioconcentration factor was 6.3. In addition, with increasing Cd concentration, the Cd content of K472 roots, stems, and leaves was positively correlated with the concentration of PCs. PC3 had the strongest response to Cd stress in roots and stems, whereas PC2 responded to stress in leaves. For practical applications, harvesting K472 in the middle of vegetative growth is an optimal strategy for the remediation of Cd-contaminated soil.