Exploring the remediation potential of Hydrangea macrophylla (Thunb.) Ser. in cadmium-contaminated soil by comparing cultivars and seedling age

Abstract

The current situation regarding soil cadmium pollution in China is far from optimistic, necessitating the exploration of more viable Cd pollution-remediating plants. Several studies have shown that ornamental plants have excellent potential for application in soil pollution remediation. However, research on the Cd tolerance capacity of Hydrangea remains scarce, and the effects of plant age on heavy metal tolerance has not been thoroughly investigated. In this study, greenhouse pot experiments were conducted with artificially prepared Cd-polluted soil at various concentrations (0–240 mg·kg−1). Two cultivars of H.macrophylla, “Endless Summer” (H.'ES') and “Classic Rood” (H.'CR'), were cultivated in different Cd-contaminated soil levels for 60 d, after which the growth response, physiological changes, mineral element absorption, and Cd concentration of different plant parts were measured. The effect of plant age on the heavy metal absorption capacity of H. macrophylla was also explored. The results showed that under Cd stress, the antioxidant activity and penetration-regulating substance content of H. macrophylla increased, and the absorption of Mg, Mn, and Zn changed. Under all Cd treatments, Cd concentrations in the roots were higher than those in the shoots of the cultivars, with a bioconcentration factor of > 1 and a translocation factor of < 1. The tolerance to Cd of the H.'CR' was stronger than that of the H.'ES'. The Cd tolerance of H. macrophylla increased with seedling age. This study indicated that H. macrophylla is a suitable candidate for Cd phytostabilization and the remediation of Cd-polluted soils to limit harm caused by Cd flow in the ecosystem.