Effect of soil characteristics on cadmium absorption and plant growth of Theobroma cacao L. seedlings

BACKGROUND: Cadmium uptake by cacao plants can affect plant growth, consumer health and commercialisation. To develop mitigation strategies, it is essential to identify the soil characteristics that could influence this absorption. To determine the relationships between cadmium absorption and the soil characteristics of cacao areas, the responses at concentrations of 0, 2, 5, 10 and 20 μg g⁻¹ of cadmium in three soils of these areas and an andisol were evaluated, using 120‐day‐old seedlings of four cultivars of Theobroma cacao L. RESULTS: In the present study, several relationships were found between chemical and physical soil characteristics and available cadmium, such as real and bulk densities, as well as contents of iron, sand, magnesium, potassium, sodium and copper. Additionally, moderate to strong correlations between potassium (r² = −0.56) and real density (r² = 0.42), with foliar cadmium, were found. Moreover, a differential deleterious effect on cacao growth in variables such as biomass was corroborated in cadmium concentrations from 5 μg g⁻¹ in soils. There were no statistical differences between cultivars with respect to cadmium uptake or plant growth. Finally, a multiple linear regression model is proposed to estimate the foliar cadmium content (r² = 0.878). CONCLUSION: Some soil characteristics such as density, as well as sand, clay, aluminium, potassium and iron contents, should be considered before establishing cacao crops to avoid cadmium accumulation. The correlation between potassium with foliar cadmium indicated that potassium could be significant in cadmium uptake mitigation strategies. The high correlation between available cadmium and foliar cadmium indicates that the quantification methodology developed using ethylenediaminetetraacetic acid extractant may be a useful diagnostic tool. © 2021 Society of Chemical Industry.