Relation of Potassium to Growth in Plants. 
BY 
T. O. SMITH 
AND 
O. BUTLER. 
I N the present study we propose to determine, first, the effect of 
absence of potassium on the growth of plants, and, second, to what 
extent recovery is possible when potassium is supplied after more or less 
prolonged growth in its absence. 
The effect of absence of potassium on growth has been studied by 
several authors, but little attention has been given to the question of 
recovery from potassium starvation. Nobbe, Schroeder, and Erdmann 1 
have studied the effect of potassium on the growth of Japanese buckwheat 
and summer rye. In the experiment with buckwheat the authors studied 
not only the effect of absence of potassium on growth, but also the effect 
produced by an addition of the element on the extent and rate of recovery 
from starvation of plants already much enfeebled. In the experiment with 
summer rye only the effect of absence of potassium on growth was studied. 
Liipke 2 studied the effect of potassium on the growth of Phaseolus 
multiflorus and P. vulgaris , and incidentally the effect of delayed additions 
of the element on recovery. 
Wilfarth 3 studied the effect of absence of potassium on the growth of 
barley, oats, lupins, and peas, and, in collaboration with Wimmer 4 — consider- 
able attention being at the same time devoted to the symptoms of potassium 
starvation — studied potato, tobacco, buckwheat, mustard, chicory, oats, and 
sugar beets. The experiments in all cases showed that potassium was 
1 Nobbe, F., Schroeder, J., and Erdmann, R. : Ueber die organische Leitung des Kaliums in 
der Pflanze. Landw. Versuchs-Stat., xiii. 321-99, 401-23, 1871. 
2 Liipke, R. : Ueber die Bedeutung des Kaliums in der Pflanze. Landw. Jahr., xvii. 887-913, 
1888. 
3 Wilfarth, H. : Vegetationsversuche iiber den Kalibedarf einiger Pflanzen. Arbeiten der deut- 
schen Landwirtschaftsgesell., xxxiv, 101 pp., 1898. 
4 Wilfarth, H., and Wimmer, G. : Die Wirkung des Kaliums auf das Pflanzenleben. Ibid., 
lxviii, 106 pp., 1902. 
[Annals of Botany, Vol. XXXV. No. CXXXVIII. April, 1921.] 
