Abstract

Voluminous literature on ion uptake by plants has been reported, but mostly it is interpreted in terms of soil factors, the contribution of plant root characteristics, if any, is neglected. Since Devaux (1916) reported cation exchange properties in plant roots and suggested that it may play an important role in explaining the uptake of cations from soil colloids or nutrient solutions, voluminous work on different aspects of cation exchange capacity (CEC) of roots has been reported. Significance of ion exchange properties of roots has been emphasised by Mattson et al. (1948, 1949) while others (Epstein, 1956; Epstein and Lagget, 1954; Laties, 1959) do not consider cation exchange capacity of much significance in formulating ion uptake theories. Some of these points have been reviewed and discussed from time to time (Epstein, 1955; Heintze, 1961; Frejat et al. 1967). The objective of the present paper is to evaluate and discuss the literature available on the origin, methods of determination, variation due to different crops or their varieties, fertilizer application and absorption of nutrients in relation to CEC of plant roots.

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