SALT REQUIREMENT FOR BUCKWHEAT PLANTS 
187 
approximately optimum only for wheat and buckwheat during the 
first four weeks of their growth after germination. It seemed highly 
desirable to determine whether the salt proportions required for opti- 
mum growth during the later periods of development, for the maturing 
of the plants, and for seed production, are the same or different from 
those above given for approximately optimum growth of seedlings. 
An attempt was made in this direction, and it is the purpose of the 
present paper to state the main results of the work in a preliminary 
way. The tests were carried out with buckwheat, first in water cul- 
tures. Similar tests were then made with sand cultures. 
The methods employed with water cultures were the same as those 
previously employed by Shive^ in his work with wheat. The seeds 
were germinated and the seedlings were mounted (three seedlings to 
each culture) in the manner described in the publication just cited 
(pp. 343-344), and were then placed in the culture vessels, which con- 
sisted of pint "Mason" jars. Each culture vessel contained 515 cc. 
of the same solution. This solution had the salt proportions, above 
given, which produced the highest yield of buckwheat tops during the 
first four weeks of growth after germination. All the seedlings were 
grown in this solution (with renewal of solutions every five or six days) 
during the first 24-day period. At the end of this time the plants were 
nearly alike. Some of the plants of each culture were in bloom and 
all the plants appeared healthy and vigorous. At the end of this 
early growth period the cultures were transferred to the 36 different 
solutions of the optimal three-salt series, each with a total osmotic 
concentration value of 1.75 atmospheres. These included all the 
possible sets of salt proportions for increments of change equal to 
one tenth of the total osmotic concentration. One culture was also 
transferred to Knop's solution and one to Tottingham's^ best solution 
for wheat, each with a total concentration equal to that of the three- 
salt solutions. The cultures were now continued, with renewal of 
solutions as before, until the seeds were mature. This required a time 
period of 28 days. The first series was conducted from October 21 to 
December 9. This was repeated between December 9 and January 
20. 
2 Shive, J. W. A study of physiological balance in nutrient media. Physiol. 
Res. i: 327-397- 1915- 
2 Tottingham, W. E. A quantitative chemical and physiological study of 
nutrient solutions for plant cultures. Physiol. Res. i: 133-345. I9I4- 
