The Effect of the Concentration of the Nutrient Solution 
on the Growth of Barley and Wheat in Water 
Cultures. 
BY 
WINIFRED E. BRENCHLEY, D.Sc., 
Lawes Agricultural Trust , Rothamsted. 
With Plate II and four Diagrams in the Text. 
F 'OR some years past much discussion has taken place as to whether the 
concentration of the nutrient solution has any appreciable effect upon 
plant growth, and at the present time the controversy is far from settled. 
Brezeale 1 carried out numerous water-culture experiments with wheat, 
using the transpiration as the criterion of growth. He states that ‘ it is 
evident that there is an optimum physical concentration of the nutritive 
solution at which water cultures of wheat thrive best, aside from variation in 
the amounts present of the different nutrient materials ’. Cameron 2 inter- 
prets these results otherwise, and claims that Brezeale has shown that, 
‘ in water-culture experiments with wheat, if a given ratio of mineral nutrients 
be maintained, relatively small effect is produced on the growing plants by 
varying the concentration over a wide range, in one case 75 parts per 
million to 750 parts per million, and this effect seems to be largely 
independent of the nature of the particular mixture of solutes ’. 
Hall and Underwood, 3 however, obtained indications that with barley 
the concentration of the nutrient solution in water culture has a definite 
effect upon growth, the total dry weight of the plants decreasing with 
the strength of the solution. Recently Stiles 4 has made further inquiry into 
the matter and states that ‘ the variation over a fairly wide range of the con- 
centration of the nutrient solution of rye and barley growing in water 
cultures produces relatively little effect on the amounts of dry matter 
produced. Below a certain concentration there appears to be a definite 
falling off in the rate of growth.’ 
When the figures given by Stiles for the dry weights of barley in 
1 Brezeale, J. F. : Effect of the Concentration of the Nutrient Solution upon Wheat Cultures. 
Science, xxii, pp. 146-9 (1905). 
2 Cameron, F. K. : The Soil Solution, pp. 40-1. 
3 Hall, A. D., Brenchley, W. E., and Underwood, L. E. : The Soil Solution and the Mineral 
Constituents of ^he Soil. Phil. Trans. Roy. Soc. 204, B. 307 (1913). 
4 Stiles, W. : On the Relation between the Concentration of the Nutrient Solution and the 
Rate of Growth of Plants in Water Cultures. Ann. Bot., vol. xxix (T915). 
[Annals of Botany, Vol. XXX- No. CXVII. January, 191C.I 
