20 
AMERICAN JOURNAL OF BOTANY 
[Vol. io, 
composition of the solution and in part upon the plant grown. Shive (21) 
demonstrated that the reaction of a nutrient solution is not noticeably 
changed by being in contact with sand. Salter and Macllvaine (15) 
studied the effect of reaction of solution on germination and on growth of 
seedlings of wheat, soybeans, corn, and alfalfa. The maximum growth of 
wheat, soybeans, and alfalfa was obtained in a solution having a reaction 
of 5.94 pH. The maximum growth for corn was obtained at 5.16 pH. 
These authors noted that the OH ion is more harmful than the hydrogen 
ion in equivalent concentrations. Meier and Halstead (14) reported that 
there is no correlation between the yield of plants and the hydrogen-ion 
concentration or the change in pH. McCall and Haag (13) varied the 
hydrogen-ion concentration in different nutrient solutions, and noted that 
the hydrogen-ion concentration has a marked effect upon the rate of growth 
of the wheat plant and is an important factor in the control of chlorosis. 
The object of the work reported in this paper was to determine the best 
proportion of the three salts KN 0 3 , Ca(H 2 P 0 4 ) 2 , and MgS 0 4 for the growth 
of wheat, and also to compare the sand- and water-culture methods with 
respect to transpiration, total weight of tops and roots, and the reaction of 
the media as determined by means of the hydrogen electrode. 
Table i. Partial Volume-molecular Concentrations and Molecular Proportions of 
KNO3, Ca{HiPOf)'i, and MgSOi in 21 Solutions all having an Osmotic 
Value of Approximately 1.00 Atmosphere at 25°C. hut Differing 
by Increments of One Eighth in the Salt Proportions 
Solution 
Molecular 
Proportions 
Partial Volume-molecular 
Concentrations 
Number 
KNO3 
Ca(H 2 
P 0 4 ) 2 
MgS 0 4 
KN 0 3 
Ca(H 2 P0 4 )-2 
MgS 0 4 
III 
R1S1. 
1 
1 
6 
.0027 
.0027 
.0165 
S2. 
1 
2 
5 
.0026 
•0053 
.0132 
S3. 
1 
3 
4 
.0024 
.0073 
.0098 
S4. 
1 
4 
3 
.0023 
.0093 
.0070 
S 5 . 
1 
5 
2 
.0021 
.0106 
.0042 
S6. 
1 
6 
I 
.0021 
.0125 
.0021 
R2S1. 
2 
1 
5 
.0054 1 
.0027 
•0135 
S2. 
2 
2 
4 
.0048 
.0048 
.0096 
S3. 
2 
3 
3 
.0045 
.0067 
.0067 
s 4 .. 
2 
4 
2 
.0042 
.0084 
.0042 
S5. 
2 
5 
1 
.0041 
.0103 
.0020 
R3S1. 
3 
1 
4 
.0075 ! 
.0025 
.0090 
S2. 
3 
2 
3 
.0070 
.0047 
.0070 
S 3 . 
3 
3 
2 
.0067 
.0067 
.0045 
S 4 . 
3 
4 
1 
.0064 
.0086 
.0021 
R4S1. 
4 
1 
3 
.0099 
! -0025 
.0074 
S2. 
4 
2 
2 
.0093 
1 .0047 
.0047 
S 3 . 
4 
3 
1 
.0085 
.0064 
.0021 
R5S1. 
5 
1 
2 
.0125 
.0024 
.0048 
S2. 
5 
2 
1 
.0113 
.0045 
.0023 
R6S1. 
6 
1 
1 
.0139 
.0023 
.0023 
Shive’s R5C2 (1.75 atm.) 
377 
1.09 
3-14 
.0180 
.0052 
.0150 
