Influence of extreme K:Na ratios and high substrate salinity on plant metabolism of crops differing in salt tolerance

Abstract

Abstract In water culture experiments effects of extreme K:Na ratios on the carbohydrate pattern in leaves and roots of bushbeans and sugarbeets in the early stages of salinity were investigated. A high substrate salinization (80 meq/1) and Cl‐ as well as SO4 2‐ as counterions were supplied. Some forms of salinization, particularly K+ and Cl‐, caused an increased content of sucrose and starch in leaves of bushbeans but not in leaves of sugarbeets. On the other hand Na+ with SO4 2‐ as counterion resulted in a decrease of the starch content in both plant species. This ion‐specific influence was also apparent in the sucrose level in roots of both crops, but bushbeans were much more affected than sugarbeets. Changes in the ratios of sucrose and starch: red. sugars were mainly as a result of changes in the sucrose and starch contents. It is suggested that the extreme K:Na ratios supplied under conditions of the different ionic regulation affects the various enzyme systems involved in carbohydrate synthesis and degradation. A change in carbohydrate pattern could be the first reaction in plant metabolism during the early stages of salinity stress. Key words: K+/Na+ Cl‐ SO4 2‐ salinitysoluble sugarsstarchbushbeanssugarbeets