The influence of rubidium-potassium levels on growth and ion accumulation in tomato

Summary

Tomato plants were cultured at various levels of rubidium and potassium in water culture. Growth as measured by dry-weight accumulation was reduced by the substitution of rubidium for potassium. The reduction in root growth was greater than the reduction in top growth; therefore, increased shoot/root values were noted with increasing rubidium concentration. In other experiments the potassium and rubidium content of the root and aerial portions were determined. It was found that rubidium tended to accumulate in the roots rather than the tops; it is postulated that this accumulation may be responsible for the observed inhibition of root growth. Potassium concentrations were similar in both the roots and tops indicating that the two cations did not behave similarly in these experiments.