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.