Accumulation and Distribution Characteristics of Cd in the Soil-<i>Lilium</i> System and the Remediation Mechanism by Soil Amendments

This study investigated the accumulation and distribution of cadmium (Cd) in the Soil-<i>Lilium</i> system and researched the effects and mechanisms of applying oyster shell powder (OSP) and organic fertilizer (OF) on reducing Cd accumulation and enhancing <i>Lilium</i> yield. The results showed that the total Cd content in soils across different planting regions was below 0.3 mg·kg⁻¹, while the Cd content in <i>Lilium</i> bulbs ranged from 0.44 mg·kg⁻¹ to 1.35 mg·kg⁻¹, indicating a consistent trend of Cd accumulation in <i>Lilium</i> bulbs. Cd contents were highest in the leaves and lowest in the bulbs, suggesting a strong translocation of Cd from the roots to the aerial parts. Both OSP and OF treatments improved <i>Lilium</i> growth and reduced Cd accumulation in the bulbs. OF significantly increased bulb yield by 62.5%, while OSP effectively reduced Cd content in the bulbs to 0.30 mg·kg⁻¹, below the regulatory safety threshold. OSP mitigated Cd accumulation by decreasing the availability of Cd in the soil and by competing with Cd for root uptake via its abundant Ca²⁺ ions. OF reduced Cd accumulation in the bulb by enhancing Cd sequestration in the fibrous roots and promoting its translocation away from the bulb. This study provides new insights into Cd dynamics in the Soil-<i>Lilium</i> system and offers practical strategies for producing <i>Lilium</i> safely.