Dec. i8» 1916 
Assimilation of Iron by Rice 
5i5 
The iron contents of all plants except those grown in the alkaline solution 
were increased by increasing the iron from 0.002 to 0.008 gm. of iron per 
liter. 
Table VIII. — Comparative weight of rice plants grown in acid, neutral, and alkaline 
solutions, with ferric tartrate as the source of iron 
Nutrient solution. 
Quantity 
of iron 
per liter. 
Flasks No. 
Green 
weight 
of stalks 
and 
leaves. 
Oven- 
dry 
weight 
stalks 
and 
leaves. 
Oven- 
dry 
weight 
of 
roots. 
Average oven- 
dry weight of— 
Stalks 
and 
leaves. 
Whole 
plant. 
(FejOa) 
in dry 
stalks 
and 
leaves. 
Gm. 
Gm. 
Gm. 
Gm. 
Per ct. 
Acid.... 
Do.. 
Neutral. 
Do.. 
Alkaline 
Do.. 
o. 002 
. 008 
. 002 
. 008 
. 002 
. 008 
f 
l 
1- 6 
7- 12 
13- 18 
19- 24 
25“ 30 
31- 36 
37 “ 42 
43 “ 48 
49 “ 54 
55 “ 60 
61- 66 
67- 72 
73- 78 
79- 84 
85- 90 
91- 96 
97-102 
IO3-IO8 
67. 8l 
56. 6l 
62. 48 
52 . 05 
67. 27 
68. 46 
S 3 - 58 
47 - 9 S 
51. 80 
57-36 
56. 86 
63. 70 
so. 22 
48. 17 
43. 01 
S 8 . 9 S 
63 - 13 
62. 90 
8. 97 
7. 92 
8. 65 
6.89 
8. 91 
9.14 
7. 01 
6. 41 
6. 91 
7 - 58 
7. 72 
8.60 
6- 75 
6. 52 
6.06 
8. 04 
8. 56 
8. 46 
2. 20 
i- 93 
2. 04 
1. 90 
2. 19 
2. 26 
1. 52 
1. 47 
1. 58 
1. 81 
1. 78 
2. 01 
1. 84 
1. 92 
1. 70 
2. 40 
2. 32 
2. 17 
8. 51 
10- 57 
0. 022 
8.31 
10.43 
. 030 
6. 78 
8.30 
. 020 
7-97 
9.84 
. 025 
6.44 
8.26 
. 019 
8-35 
10. 65 
. 022 
Experiment 9 (Source of iron in acid and neutral solutions: Dialyzed 
iron).—Dialyzed iron was tested as a source of iron in acid and neutral 
solutions. From the previous experiments it seemed evident that this 
form of iron would be of very low availability, but as it has been recom¬ 
mended as a source of iron in certain nutrient solutions it was thought 
advisable to make the test. The comparison between dialyzed iron and 
ferrous sulphate in the neutral solution was carried out at one time and 
the comparison between the neutral and acid solutions with dialyzed 
iron at another time. The two tests are combined in one table for 
conciseness. 
Two plants were grown in each flask, six flasks were taken as a unit, 
and the unit duplicated for each treatment. Plants in flasks 49 to 84, 
the comparison between acid and neutral solutions, were grown but 25 
days; all others were grown 40 days. The data of growth are given in 
Table IX. 
All plants except No. 25 to 48 were markedly chlorotic at all times. 
Dialyzed iron apparently afforded practically no available iron when 
used in the neutral solution at the rate of either 0.002 or 0.008 gm. of iron 
per liter. In the acid solution it was slightly more available than in the 
neutral, although utterly inadequate for the needs of the plant. 
