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

The relation between activity of soluble acid invertase and sucrose content in leaves of young bushbeans (salt sensitive) and sugarbeets (salt tolerant) and ion‐specific effects of salinity environment were investigated. For comparison the response of isolated invertase from both plant species to ion combination and ion concentration was investigated. The plants were grown in water culture under controlled conditions.

In busbean leaves invertase activity decreased while sucrose increased. K⁺ with Cl^‐ as counterion was most effective “in vivo”;. However, there was little change in invertase activity or sucrose content in sugarbeet leaves. Independent of the origin of the enzyme, invertase activity was not affected by either ion concentration or ion combination “in vitro”;. Acid invertase might be a key enzyme in the utilization of carbohydrates. The ionic effect on acid invertase activity and carbohydrate content in intact plant tissue could be a possible indicator of salt tolerance of crops.