Jan., 1923] BAKKE AND ERDMAN -— CULTURES OF MARQUIS WHEAT 
21 
Experimental 
The plan of the experiment was in all its essential details the same as 
that recommended by the Special Committee of the National Research 
Council on Salt Requirements of Agricultural Plants (23). 
The salts used were especially prepared for this work at the request of 
this committee by the J. T. Baker Chemical Company. The molecular 
proportions and partial volume-molecular concentrations of the three salts, 
KNO3, Ca(H 2 P0 4 )2, and MgS0 4 , are given in table 1. These dilutions are 
based on freezing-point determinations made by Dr. Shive. 
The wheat used was of the “Marquis” variety, secured through Dr. 
Stakman of the University of Minnesota. In the matter of securing uni¬ 
form seedlings of 4 cms. length, the seeds were first soaked in a germinating 
solution (Shive’s R5C2, 0.1 optimal concentration), and later distributed 
evenly upon a germinating net made by taking ordinary mosquito netting 
which had been thoroughly paraffined; this net was tied tightly over a 
5-gallon glazed stoneware jar. Provision was made so that two liters of 
fresh germinating solution could be added from the bottom of the container 
each day. In order to maintain a temperature of approximately 18 0 C., 
the jar was kept in a water bath. It then became a simple matter to secure 
the seedlings of desired uniformity. For the water cultures the seedlings 
were mounted in cork stoppers to fit 1-quart Mason jars in the manner 
adopted by Tottingham. Five plants were used for each culture. 
The sand used was obtained from the Clayton Sand Company of Clayton, 
Iowa, and gave a mechanical analysis as follows: 
Millimeters in Diameter 
1.00-0.5 
0.5-0.25 
0.25-0.10 
0.10-0.05 
0.05-0.00 
0.06% 
62.80% 
14.12% 
21.40% 
1.62% 
A chemical analysis showed the sand to contain 98.5 percent Si 0 2 and 
0.54 percent iron and aluminum hydroxide. It had a water-holding capac¬ 
ity of 21 percent on the dry-weight basis. [Hilgard method with column 
I cm. high (3).] 
Regarding the optimum moisture content of a soil as 50 percent of its 
maximum water-holding capacity, the sand cultures were maintained at a 
moisture content of 11 percent. 
After the experiment had been in progress for one month, it was realized 
that the 11 percent moisture was not sufficient to supply the needs of 
maximum transpiration, and consequently the moisture content was raised 
to 16 percent for the remaining period of experimentation. 
Glazed stone or butter jars 12.5 cm. high and 19.0 cm. in diameter were 
used for these cultures. A glass suction tube, the lower end of which was 
