152 
Journal of Agricultural Research 
Vol. XIV, No. A 
As the result of extensive A comparative studies with both wheat 
(Triticum spp.) (6) and buckwheat (Fagopyrum esculentum) (7), it has 
been found that, under certain experimental conditions and for a period of 
growth of about four weeks directly following germination, 3-salt solu¬ 
tions in suitable concentrations and with the proper proportions of the 
three salts, monopotassium phosphate, calcium nitrate, and magnesium 
sulphate (with a trace of iron added), are equal in plant-producing power 
to any of the more complex solutions now in common use. It seemed 
highly desirable to determine whether the salt proportions demanded 
for approximately optimum development during the later periods of 
growth, for the maturing of the plants, and for seed production are the 
same or different from those which produce the best growth during the 
early stages of development. An attempt has been made in this direc¬ 
tion, and the present paper describes an experimental study of the salt 
requirements of buckwheat plants in water cultures, for the later periods 
of development from the flowering stage to the maturing of seeds. These 
results are compared with those of a similar study (7), previously carried 
out, of the development of young buckwheat plants during the growth 
period from germination to the flowering stage. A similar comparative 
study of salt requirements for buckwheat has been carried out with 
sand cultures. The results with water cultures will alone be presented 
in the following pages; those obtained with sand cultures will be reserved 
for later publication. 
Buckwheat was chosen for these tests for the reason that in its life 
cycle it presents two distinct physiological growth periods which extend 
over nearly equal periods of time. The first of these occupies the period 
between the germination of the seeds and flowering, the second interval 
extending over the period from the flowering stage to the maturity of 
the seeds. It is a quick-growing plant and matures in a comparatively 
brief period of time, requiring, under favorable conditions, about 60 
days to complete its active growing period. 
EXPERIMENTAL PROCEDURE AND METHODS 
The tests to be described in the following pages were carried out with 
the optimal series of 3-salt solutions 1 previously employed by Shive in 
his work with wheat and with buckwheat. This optimal series com¬ 
prised 36 different solutions, all having approximately the same total 
osmotic concentration value of 1.75 atmospheres. The three salts were 
so distributed as to include all possible sets of proportions of the three 
salts when the partial concentrations of the three components were made 
to vary by equal increments of one-tenth of the total osmotic concen¬ 
tration. To each solution was always added the usual trace of iron, in 
the form of ferric phosphate. 
*A table of these solution formulas has been given in previous publications: Shive, J. W. (< 5 ), and McCall, 
A. G. (j). A discussion of the methods of calculation by which the partial osmotic concentration values 
and also the volume-molecular partial concentrations of each salt in these solutions may be calculated, 
is given by Tottingham (8, p. 177-182, IQ2). 
