Cadmium-induced changes in leaf nutrient concentrations in sugarcane

Cadmium (Cd) is a toxic element for higher plants and it has been suggested that sugarcane (Saccharum spp.) can be used as a phytoextractor for this metal. Nutrient management represents an alternative for coping with Cd toxicity, although the importance of mineral nutrition on Cd stress tolerance has been scarcely investigated. The present study examined the effect of two levels of Cd (0 and 1 mM), in a nutrient solution used for irrigation, on leaf nutrient concentrations in sugarcane cultivar CP 72-2086 grown hydroponically under greenhouse conditions. After 50 days of treatment with Cd supplied at intervals of five days, the concentrations of N, P, K, Ca, Mg, Fe, Zn, Mn, B and Cd in sugarcane leaves were determined. Only N concentrations were negatively affected by the addition of Cd in nutrient solution, and were 50.3% lower compared to that observed in control plants. In contrast, concentrations of P, Mg, Zn and B were significantly higher in leaves of Cd-treated plants by approximately 34, 29, 37 and 40%, respectively, in comparison to control plants. Cadmium treatment had no significant effects on leaf concentrations of K, Ca, Fe and Mn, and this heavy metal was only detected in Cd-treated plants, with an average leaf concentration of 7.97 mg kg -1 dry matter. The results indicate that cultivar CP 72-2086 is tolerant to Cd concentrations of 1 mM under the conditions tested, and with the exception of N, all other nutrients were not negatively affected by this metal. This, along with high biomass production and ease of cultivation, makes sugarcane one of the most interesting crops for metal phytoextraction purposes.