5*4 
Vol. VII, No. 13 
Journal of Agricultural Research 
markedly increased in acid and neutral solutions, but was unaffected 
in the alkaline solution by increasing the iron from 0.002 to 0.008 gm. 
per liter. 
Table VII. — Comparative weights of rice plants grown in acid , neutral , and alkaline 
solutions , with ferric citrate as the source of iron 
Nutrient solution. 
Quantity 
of iron per 
liter. 
Gm. 
Acid. 
Do... 
Neutral.. 
Do... 
Alkaline. 
Do... 
. 008 | 
Average oven- 
dry weight of— 
Flasks 
1-6 
7-12 
13-18 
19-24 
25-30 
31-36 
37-42 
43-48 
49-54 
55-6° 
61-66 
67-72 
Green 
weight 
ot stalks 
and 
leaves. 
Gm, 
87. go 
87 . OI 
124. 45 
143. 40 
87-3 1 
84.43 
13°. 95 
no. 12 
91. 16 
88. 65 
70. 30 
91. 64 
Oven- 
dry 
weight 
of stalks 
and 
leaves. 
Gm. 
11. 02 
10. 96 
17. 42 
18. 08 
11. 19 
11. 08 
16.35 
13 - 73 
ii- 55 
11. 28 
8. 82 
ii- 75 
Oven- 
dry 
weight 
of roots. 
Gm. 
2 . 13 
2- 15 
3. 28 
3- 65 
2. 23 
2. 28 
3-27 
2. 60 
2. 34 
2. 55 
2. 11 
2. 82 
Stalks 
and 
leaves. 
Gm. 
II. 42 
10. 29 
Whole 
plant. 
Gm. 
13- 87 
12. 76 
Iron 
(FeaOa) 
in dry 
stalks 
and 
leaves. 
Per ct. 
. Ol6 
. 020 
No. 
10.99 
13- 13 
0. 019 
i7- 75 
21. 27 
. 025 
II. 14 
13- 40 
. 016 
15. 04 
17.98 
. 020 
The percentages of iron in plants grown in acid solutions were slightly 
greater than in plants grown in neutral and alkaline solutions. The 
iron contents of plants from all three solutions were slightly increased by 
increasing the iron from 0.002 to 0.008 gm. per liter. 
Experiment 8 (Source of iron, in acid, neutral, and alkaline solu¬ 
tions: Ferric tartrate).—This experiment was conducted to see whether 
other organic iron compounds would show the same availability as ferric 
citrate. The two quantities of iron from ferric tartrate were used in the 
three nutrient solutions. Two plants were grown in each flask, six 
flasks were taken as a unit, and the units triplicated for each treatment. 
The growth of plants and percentages of iron in the stalks and leaves 
are given in Table VIII. 
During the growth the plants were all of good color except No. 37 to 54 
and 73 to 90, which were slightly yellowish from the fifteenth to thirtieth 
day, but of good color the rest of the time. 
With 0.002 gm. of iron per liter growth was considerably better in the 
acid solution than in the neutral or alkaline. With 0.008 gm. of iron 
per liter growth was practically equal in all three solutions, though 
possibly there was a slight depression in the neutral solution. Increasing 
the iron did not increase growth in the acid solution, but did increase 
it in the neutral and alkaline solutions to a small extent. 
The percentages of iron in plants grown in the acid solutions were very 
slightly greater than in plants grown in the neutral and alkaline solutions. 
