July 22, 1918 
Salt Requirements for Buckwheat Plants 
155 
the seeds) was conducted from October 18 to December 9, 1916. During 
this period the maximum temperature recorded was 30° C., on Novem¬ 
ber 3, and the minimum was 11 0 on December 4. The rate of evaporation 
from the atmometer gave a daily mean of 16.8 cc, a maximum daily rate 
of 25.6 cc, on November 21, a minimum daily rate of 7.4 cc, on October 20, 
and a total water loss from the instrument of 874 cc. The second series 
of cultures, which was just like the first, extended over the period from 
December 9, 1916, to January 30, 1917. During this period a maximum 
temperature of 30° occurred on December 28, and a minimum of 7 0 on 
January 1. The rate of water loss from the porous-cup atmometer, 
indicating the evaporating power of the air gave a daily mean of 17.7 cc, 
a maximum daily rate of 25.2 cc, on January 13, and a minimum daily 
rate of 13.5 cc, on January 29. The total loss from the instrument for 
the entire time was 919 cc. 
In the following sections, the results obtained with these buckwheat 
cultures grown from the flowering stage to maturity in an optimal series 
of 3-salt solutions with their different sets of salt proportions will be com¬ 
pared with those obtained from a similar study (7) previously carried out 
with buckwheat grown in the solution cultures of the same series, but 
conducted only to the flowering stage, a period of about four weeks 
directly after germination. The comparisons will be made with refer¬ 
ence to the dry weights of tops and of roots and also with respect to the 
relative amounts of water lost by transpiration during the growth periods. 
I. —DRY WEIGHTS 
A.—Presentation of Data 
The tops, roots, and seeds of the cultures grown to maturity were 
weighed separately. Three sets of dry-weight measurements are there¬ 
fore available. Since the results obtained with the two corresponding 
series were in very close agreement, only average dry-weight yields will 
here be considered. These are presented in Table I. In every qase these 
measurements represent the values obtained by averaging the corres¬ 
ponding data of the two series conducted during different time periods. 
In the first column are given the culture numbers. These refer to the 
positions which the cultures occupy on the triangular diagram graphi¬ 
cally representing the variations in the salt proportions and partial 
osmotic concentrations of the series of solution cultures here employed. 
Since the scheme of diagramatic representation fox this series of solution 
cultures has been explained in a previous publication (6, p. 341) and has 
since been employed by McCall (5,4), the description of the diagram may 
here be omitted. Table I gives the average absolute dry weights, in 
grams, of tops, roots, and seeds, and also the dry-weight values in terms 
of the corresponding value of culture R1C1 considered as unity. These 
relative yields were obtained by dividing the average absolute dry- 
weight value of each culture by the corresponding value of culture R1C1. 
The maximum relative yields are here indicated by bold-face type. The 
