Dec, 18, 191^ 
Assimilation of Iron by Rice 
521 
iron, since the relative growths made in acid, neutral, and alkaline solu¬ 
tions depended on the kind and quantity of iron supplied. This is well 
shown by Table XIII, which summarizes the relative growths of stalks 
and leaves made in the three solutions with different kinds and quantities 
of iron. The growth of stalks and leaves 1 made in the acid solution is 
always taken as 100; growths in the neutral and alkaline solutions are 
expressed relative to 100. 
Table XIII .—Relative growths of rice plants in acid , neutral , and alkaline solutions 
with different sources and amounts of iron 
Source of iron in nutrient solutions. 
Iron per 
liter added 
to nutri¬ 
ent solu¬ 
tions. 
Relative growths in— 
Table 
from 
which 
data 
were 
calcu¬ 
lated. 
Acid 
solu¬ 
tion. 
Neutral 
solu¬ 
tion. 
Alka¬ 
line so¬ 
lution. 
Gm. 
Ferrous sulphate... 
0. 002 
100 
88 
II 
Do. 
100 
7 A 
SI 
III 
Do..... 
100 
95 
0 ■ 
95 
IV 
Do... 
. 008 
\ 
Do. 
. 004 
f 100 
105 
I 
Do.■.. 
. 002 
100 
107 
II 
Do... 
008 
100 
132 
II 
Do... 
IOO 
III 
2 
IV 
Ferric chlorid. 
. 002 
100 
99 
26 
VI 
Do.. 
. 008 
IOO 
107 
26 
VI 
Ferric citrate.. 
. 002 
IOO 
85 
86 
III 
Do. 
IOO 
07 
IV 
Do... 
ICO 
Vt- 
IOI 
104 
VII 
Do. 
. 008 
IOO 
85 
58 
VII 
Ferric tartrate. 
. 002 
IOO 
80 
76 
VIII 
Do. 
. 008 
IOO 
96 
IOO 
VIII 
Dialyzed iron. 
. 008 
IOO 
27 
IX 
It is evident that with 0.002 gm. of iron per liter, growth was more 
or less best in the acid solution, while with 0.008 gm. of iron per liter 
growth was best in the neutral solution with some forms of iron. Growth 
with most, but not all, forms and quantities of iron was strikingly inferior 
in the alkaline solution. 
The effect on growth of increasing the quantity of iron in the different 
solutions is significant in throwing light on the availability of the iron 
in these solutions. In Table XIV are shown the extents to which growth 
was increased or decreased by increasing the iron in the three solutions 
from 0.002 to 0.008 gm. per liter. The growth made in each solution 
(acid, neutral, or alkaline) with 0.002 gm. of iron per liter is taken as 100, 
and the growth made with 0.008 gm. of iron per liter in these solutions 
is expressed relative to 100. 
1 In this and previous comparisons more significance was attached to the weight of stalks and leaves 
than to the weight of the whole plant. The weights given for the roots must have been very slightly in 
excess of the true values, as the roots were always more or less contaminated with a precipitate that could 
not be removed by washing. Also, the root growth relative to top growth is markedly influenced in some 
cases by an insufficiency of a mineral nutrient. 
