Root cation exchange capacity of sugarcane: An evaluation of methods

Abstract

AbstractAn investigation was undertaken to select the appropriate methods and sampling times for measuring root cation exchange capacity (CEC) for four sugarcane cultivars (H50–7209, H57–5174, NCo 310 and H56–5840) grown in solution and soil culture. The three methods selected for measuring root CEC in decreasing order of differentiation between cultivars, were isotope (Ca45) dilution method using chilled fresh roots, calcium adsorption method using chilled fresh roots and a titration method using ground dry roots. The root CEC results were expressed as CEC/weight (mEq/l00 g dry roots) and CEC/area (mEq/100 g saturated calcium nitrate solution; this measures the surface area index of the root). The range of CEC values for roots was narrow between the cultivars examined. In these experiments CEC/area were different for the four cultivars in the same order of ranking. The values of CEC/weight were large when measured at 60 days in solution culture and at 120 days in soil culture. The CEC/area for the roots of sugarcane cultivars H50–7209, H57–5174, NCo 310 and H56–584O at 60 days in solution culture as measured by isotope dilution method were 0.40, 0.45, 0.50 and 0.51 mEq/100 g saturated calcium nitrate solution, respectively.