Cadmium mobility, uptake, and accumulation in spinach, kale, and amaranths vegetables as influenced by silicon fertilization

Abstract

Using silicon (Si) can reduce heavy metal stress in plants, which have been grown in soil contaminated with cadmium (Cd). This study aimed at evaluating the influence of Si on Cd uptake, mobility, and compartmentation in leafy vegetables: spinach, kale, and amaranths. The study was conducted in both greenhouse and field experiments, which included four treatments: Cd, Cd + Si, Si, and control. Data were collected on root, stem, and leaves Cd concentration, transfer index (TI), translocation factor (TF), and Cd uptake by leafy vegetables. The Cd concentration was higher in roots than in stems and leaves in all the treatments whereas its TI and TF were less than one with spinach having the highest TF. Generally, Cd transfer was highest in roots and least in leaves in all treatments and it increased with age of the vegetables. Spiking the soils with Cd in the greenhouse resulted in higher Cd concentration in leafy vegetable tissues than in the field experiment. With application of Si, there was a significant reduction in the concentration of Cd in plant tissues of between 20 and 40%, which further resulted in strong and positive relationships between the Cd concentration in the soil and plant tissues. Therefore, the study recommends against the production of leafy vegetables in Cd contaminated soils for human consumption. Nonetheless, under unavoidable circumstances, we recommend application of Si to alleviate the transfer of Cd to edible tissues of leafy vegetables.

KEYWORDS:

• Cadmium
• cadmium concentration
• heavy metals
• mobility index
• silicon
• translocation factor

Acknowledgment

The authors hereby acknowledge Kenyatta University for technical support for this study.

Disclosure statement

No potential conflict of interest was reported by the authors.