Oct., 1922] TURNER EFFECTS OF CERTAIN MINERAL SALTS 
419 
stant, but varied the salt proportions of his solution chiefly around mono- 
basic potassium phosphate, which constituted from one tenth to seven 
tenths of the total salt concentration employed. He actually made up his 
solutions on the basis of osmotic pressure (.6 percent solution corresponding 
to an osmotic pressure of 2.50 atmospheres), but we may, for convenience, 
use total concentrations in the discussion, since for these dilute solutions 
osmotic pressure varies with the concentration. 
Tottingham's variations in the proportion of salts gave a total of 84 
solutions. In 28 of these, one tenth of the total concentration was due to 
monobasic potassium phosphate; in 21 solutions, two tenths; in 15, three 
tenths; in 10, four tenths; in 6, five tenths; in 3, six tenths; in i, seven tenths. 
Cultures were grown in each of the solutions. Using the figures on his 
triangular diagrams, the top-root ratios have been averaged for at least ten 
cultures from each of those percentages of monobasic potassium phosphate, 
giving ten or more solutions, while ratios for all the cultures have been 
averaged for the remaining triangles. The results are again very suggestive 
(table 3a). . , . 
Table 3a 
Partial Concentration of KH2PO4 in a .6% Solution 
1 
•3 
•4 
•5 
.6 
• 7 
Tops 
3.1 2.84 
2.69 
2.57 
2.77 
2.43 
2.42 
Roots 
With the exception of one result, the ratios of tops to roots shown in 
table 3a vary inversely with the concentration of monobasic potassium 
phosphate in the solution. Whatever importance we may attach to this 
table, it stands out in contrast to table 3 in emphasizing the importance of 
the composition of the nutrient solution in affecting top-root ratios. 
Cameron (5) and others have called attention to the fact that the rela- 
tive proportion of mineral constituents has a marked effect on growth, 
causing tops to grow relatively faster than roots in some cases, at other 
times causing roots to make the more rapid growth. 
The step from a plant like wheat or barley grown in a nutrient solution, 
to a deciduous orchard plant growing in the soil, is not an immediate one, 
but it might not be out of place to mention here some pruning results of 
Chandler (6) in so far as they concern the ratio of top to root growth in 
certain orchard trees. He gives data supporting the following statements: 
While the nitrate has increased both top and root growth, it has not increased root 
growth to as large an extent as it has increased top growth. Thus, while the top growth 
of fertilized trees [peaches] is twice as great as that of the unfertilized trees, the root growth 
is only 50 percent greater. 
