Effect of Removal of a Part of the Root System on the Subsequent Growth of the Root and Shoot

Removal of up to 50 per cent. of the roots of barley and rye has no effect on the growth-rate of the root which is the same as in the intact plant. In contrast the growth-rate of the shoot decreases as more roots are removed. When more than 50 per cent. of the roots are removed, root growth declines but not so rapidly as that of the shoot. Similar results are obtained by the removal of lateral roots of tomato but root growth begins to decline when 40 per cent. of the lateral roots are removed. The uptake of potassium by barley plants with proportions of the root system excised is closely proportional to the dry-matter increase when the nutrient supply is not limiting. In conditions of low nutrition the potassium uptake is less than the dry-matter increase.