July 22, 1918 
Salt Requirements for Buckwheat Plants 
153 
In the work previously carried out with buckwheat (7), tests of the 
36 different sets of proportions of the three salts of this series showed 
that the best growth of tops and of roots during the early physiological 
growth period extending from germination to the flowering stage was 
produced by a solution containing the three salts in the following volume- 
molecular proportions: Potassium phosphate (KH 2 P 0 4 ), 0.0144 m; cal¬ 
cium nitrate [Ca(N 0 3 ) 2 ], 0.0052 m; and magnesium sulphate (MgS 0 4 ), 
0.0200 m. This solution was further characterized by having four-tenths 
of its total osmotic concentration derived from potassium phosphate, 
four-tenths from calcium nitrate, and two-tenths from magnesium sul¬ 
phate. 
The methods 1 employed with the water cultures here considered were 
similar to those previously adopted in the work with wheat and with 
buckwheat. The Japanese variety of buckwheat was used. The seed¬ 
lings were carefully selected for uniformity of size and vigor, and when 
about 5 cm in height were transferred to the culture vessels, which 
consisted of pint Mason jars. Each culture vessel had a capacity of 
515 cc. Three buckwheat plants were included in each culture. 
In order to determine the proportions of the three salts required to 
produce approximately optimum growth of buckwheat plants during 
the later period of development, from the flowering stage to the matur¬ 
ing of the seed, it was of course essential that the plants of all the cultures 
at the beginning of this later period of growth should be as nearly uni¬ 
form as possible. With this in view, many more cultures than the 36 
comprising the series for study were prepared at the same time with 
selected seedlings all nearly uniform in size and vigor. The selected 
seedlings were transferred to the culture vessels, each of which had pre¬ 
viously been provided with 515 cc of the same solution. This solution, 
with a total osmotic concentration value of 1.75 atmospheres, had the 
salt proportions above given. These produced the highest dry weight 
yield of buckwheat tops and of roots during the early growth period, 
between germination and the beginning of the flowering stage. All the 
seedlings were grown in this solution, with renewal of solutions every 
four or five days during the first 24-day growth period after the seedlings 
had been transferred to the solutions. At the end of this time period 
the plants of each culture had begun to bloom and all the plants appeared 
healthy and vigorous, the cultures throughout showing excellent uni¬ 
formity. 
Thirty-six cultures were now selected from the larger number at 
hand; these were transferred to the 36 different solutions comprised in 
the optimal 3-salt series. All the solutions of the series had a total 
osmotic concentration value of approximately 1.75 atmospheres, but 
they differed from each other in the proportions of the component salts. 
For purposes of comparison, one culture was also transferred to Knop’s 
1 For a description of the methods employed in these studies, see Shive, J. W. (6). 
