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Abstract

An investigation was undertaken to measure the root properties, weight, surface area index (measured by the weight of saturated calcium nitrate solution covering the root surface), cation exchange capacity (CEC) and anion exchange capacity (AEC) of sugarcane roots and relate them to the uptake of N, P, K, Ca, Mg, Si and S by four sugarcane cultivars (H50–7209, H57–5174, NCo 310 and H56–5840) grown in solution and soil culture. The root CEC and AEC results were expressed as CEC or AEC/weight (mEq/100 g dry roots), CEC or AEC/area (mEq/100 g saturated calcium nitrate solution) and mEq CEC/pot or AEC/pot. In soil and solution culture, both CEC and AEC indices were not related to the amounts of cations and anions sorbed by the plant, probably because total ion uptake is primarily controlled by active process rather than exchange. In solution culture, the weight, surface area index, CEC and AEC of roots in each pot were significantly correlated with shoot weight and the uptake of N, K, Ca, Mg and S. The best relationship was obtained with the surface area index. In soil culture, only root weight was significantly correlated with shoot weight and the uptake of N, Mg and S.