July 22 , 1918 
Salt Requirements for Buckwheat Plants 
165 
have been plotted on triangular diagrams like those of figure 1, which 
graphically represent the relative yields of tops. The effect of the differ¬ 
ences in the developmental stages of the plants upon the positions and 
ranges of the areas of high and low yields of roots will be compared by 
referring to the triangular diagrams of figure 2, in which the lower dia¬ 
gram represents the average yields of roots from series A, and the upper 
one represents the yields from series B. 
(a) Comparison of the) effects of the various osmotic salt pro¬ 
portions FOR THE TWO PHYSIOLOGICAL GROWTH PERIODS—CONSIDERA¬ 
TION of THE relative dry weights of roots. —A comparison of the 
diagram of series A with that of series B shows the main areas of low 
yields to lie on opposite margins of the diagram. There is no overlapping 
of the areas of low yields. The cultures (R1C4 and R1C1) producing 
lowest yields of roots in series A and B, respectively, are the same ones 
which produced also the minimum yields of tops in the corresponding 
series. The osmotic proportions of the three salts characterizing these 
two solutions are therefore the same for both tops and roots. 
The main areas of high yields on the two .diagrams occupy central 
regions lying chiefly on opposite sides of the vertical axes of the diagrams. 
The main high area of series A extends to the left and includes the three 
marginal cultures R4C1, R5C1, and R6C1, while the main area of high 
yields on the diagram for series B extends to the right margin at culture 
R3C6. There is a certain amount of overlapping of the areas of high 
yields, but only a single culture is shown which is common to areas of 
high yields on the twp diagrams. This culture (R3C5), which marks the 
lower limit of the range of high yields in series A, produced the maximum 
yield in series B. The maximum yield of roots in series A and that in 
series B occurred with the cultures R4C2 and R3C5, respectively. These 
two cultures have already been shown on the diagrams of figure 1 as pro¬ 
ducing the highest dry weights of tops in their respective series. Thus 
the osmotic proportions characterizing these two solutions, like those 
characterizing the solutions producing the lowest yields in the two series 
are the same for both tops and roots. 
It is obvious that there is as little similarity, with respect to the dis¬ 
tribution of the areas of high and low yields, between the two diagrams 
representing the yields of roots (fig. 2) as there is between those repre¬ 
senting the yields of tops (fig. 1). From these considerations it is clear 
that the various osmotic proportions of the three salts in the solutions 
here employed affect the growth of roots as differently during the two 
developmental periods as they do the growth of tops. 
A comparison of the two diagrams of figure 2 with the corresponding 
ones of figure 1, representing the relative yields of tops, brings out some 
very striking correlations between the growth of tops and that of roots. 
As has already been pointed out, the cultures in each of the two series 
which produced the highest yields of tops, gave also the maximum root 
