A Sunflower and Dolomitic Lime Experiment to Modify Cadmium Concentration in Cacao

Cadmium (Cd) is a toxic heavy metal naturally present in soils and is readily absorbed by edible plants, including cacao, the main ingredient of chocolate foods. High Cd levels in cacao beans pose a public health risk, leading to stringent regulations, particularly in the European Union, which adversely affect small-scale cacao farmers. This study aimed to evaluate the effects of sunflower (Helianthus annuus) and dolomitic lime on Cd levels in one-month-old cacao plants (Theobroma cacao) and the soils they grew in. A greenhouse experiment was conducted, where sunflower and cacao were grown together under two levels of soil Cd exposure, with dolomitic lime added to some treatments. The results indicated that dolomitic lime significantly reduced (P < 0.05) Cd concentrations in cacao, while sunflower presence increased Cd accumulation in cacao, possibly due to the acidic conditions created by sunflower roots. A negative correlation was observed between soil pH and Cd levels in soil. These findings suggest that dolomitic lime may be a viable strategy to mitigate Cd uptake in cacao under low to moderate soil Cd contamination.