TITLE:
Pitfalls and Uncertainties of Using Potentiometric Titration for Estimation of Plant Roots Surface Charge and Acid-Base Properties
AUTHORS:
Grzegorz Jozefaciuk, Alicja Szatanik-Kloc, Malgorzata Lukowska, Justyna Szerement
KEYWORDS:
Charge, Density, Dissociation, Method, Plant, Root, Surface, Titration
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.13,
June
6,
2014
ABSTRACT: Amount and properties
of roots surface charge are important for nutrient uptake and balance in plants.
Roots surface charge markedly varies at different rizosphere conditions (particularly
pH and ionic strength), which can markedly alter during vegetation season. Among
recently available measuring methods, surface charge-pH dependence of roots (as
well as other biological objects) is most easily evaluated by potentiometric titration.
Use of this method is also easy at different ionic strengths. Potentiometric titration
also allows for estimation of the distribution of charge generating surface groups.
However, many applications of this method seem to be based either on incorrect methodical
or theoretical approaches. In this paper we discuss the methodical and theoretical
backgrounds of the titration method. Basing on experimental titration curves of
roots of barley grown in nutrient solution, we show inconsistency of surface charge
results obtained at different measuring conditions. Limitations of theoretical interpretations
of the results are outlined also.