Dec. i8,1916 
Assimilation of Iron by Rice 
5i3 
The color of the plants during growth was as follows: At 10 days plants 
19 to 36 and 55 to 72 were a good green, 1 to 18 were a lighter green, 
37 to 54 were a yellowish green, 73 to 108 had a still poorer color; at 20 
days plants 19 to 36 and 55 to 72 were a fair green, 1 to 18 and 37 to 54 
were markedly chlorotic, 73 to 108 were more chlorotic; at 30 days plants 
19 to 36 and 55 to 72 were of slightly poor color, in 1 to 18 and 37 to 54 
color was improved though still chlorotic, 73 to 108 were strongly chlo¬ 
rotic. The color and growth of plants were, on the whole, noticeably 
inferior to that of plants grown with ferrous sulphate as the source of iron. 
The growths made in the acid and neutral solutions were approxi¬ 
mately equal and much superior to those in the alkaline solution. Growth 
was markedly increased in all three solutions by increasing the iron from 
0.002 to 0.008 gm. per liter. 
The results differ from those of previous experiments with ferrous 
sulphate because in acid and neutral solutions growth was increased less 
by increasing the iron from 0.002 to 0.008 gm.; with 0.002 gm. of iron 
growth was much less in the alkaline solution relative to growth in neutral 
and acid solutions; increasing the iron from 0.002 to 0.008 gm. in the 
alkaline solution measurably increased growth instead of markedly 
depressing it. 
The .percentages of iron in the dry substance of stalks and leaves varied 
very little between plants from the different solutions. In each case 
plants grown in solutions with 0.008 gm. of iron per liter contained very 
slightly more iron than those grown in similar solutions with 0.002 gm. 
of iron. It will be noted that there was not such a marked increase in the 
assimilation of iron from the acid solution as in tests with ferrous sulphate. 
Experiment 7 (Source of iron in acid, neutral, and alkaline solutions: 
Ferric citrate).—Ferric citrate as a source of iron was compared with 
ferrous sulphate in experiments 3 and 4, but only 0.002 gm. of iron per 
liter was used. In this test both 0.002 and 0.008 gm. of iron per liter 
were compared in the different solutions. 
Three seedlings were grown in each flask, but 200 c. c. flasks were used 
only during the first 15 days, 500 c. c. flasks during the next 15 days, 
and 1,000 c. c. flasks during the last 10 days of growth. Six flasks were 
taken as a unit and the units duplicated for each treatment. The growth 
of plants and percentages of iron in dry stalks and leaves are shown in 
Table VII. 
During the first 30 days all plants were of a good green color, except 
No. 61 to 72, which were yellowish green. All plants had a good color 
during the last 10 days. 
As in the previous tests with ferric citrate, the growth was equal in 
acid, neutral, and alkaline solutions with 0.002 gm. of iron, per liter. 
With 0.008 gm. of iron per liter growth was practically equal in the acid 
and neutral solutions, but much less in the alkaline. Growth ’was 
