AGRICULTURE: E. C. MILLER 
431 
of the cells, or to a difference in the thickness of the leaves of the three 
plants or to both of these factors. 
The average difference between the maximum and minimum amount 
of dry matter in the leaves during the day from 7 a.m. to 7 p.m. was 4 
grams for corn, 4.8 grams for kafir and 8.0 grams for milo. Table 2 
shows the rate of increase in dry matter for corn, kafir and milo in grams 
per square meter of leaf for each of the two hour periods during the day, 
from 7 a.m. to 5 p.m. 
TABLE II 
Average Rate of Increase of the Dry Matter for Each Square Meter of Leaf for 
Corn, Kafir and IMilo During Each Two Hour Period of the Day 
PLANT 
A. M. 
p. 
M. 
7-9 
9-11 
11-1 
1-3 
3-5 
grams 
grams 
grams 
grams 
gram 
2.2 
1.1 
0.8 
0.7 
0.8 
Kafir 
1.7 
1.2 
0.7 
1.2 
0.7 
Milo 
1.3 
1.5 
2.2 
2.0 
0.8 
Two explanations are possible for these results. The milo plant 
either manufactures food in the leaves more rapidly than the corn or 
kafir, or the rate of translocation is higher in the latter plants. In 
most cases, under the conditions of these experiments, the leaves of corn 
were badly wilted during the greater portion of the day. The kafir 
leaves also wilted but not to the extent of the corn, while the leaves of 
milo very seldom showed signs of wilting. The smaller increase in dry 
matter in the leaves of corn and kafir during the greater portion of the 
day in comparison to the leaves of milo is evidently due to the severe 
climatic conditions. The high evaporation of water from the leaves of 
corn and kafir exceeds the intake by the roots and as a consequence, the 
water content is lowered to such an extent as to interfere with the vital 
processes of the protoplasm. The rise in temperature of the leaves due 
to the decreased transpiration may also be a factor in lowering the photo- 
synthetic power of these plants. 
The results indicate that under the conditions of these experiments, 
the sorghums and more particularly milo, can absorb water from the 
soil and transport it to the leaves more rapidly in proportion to the loss 
of water from the plant than can corn. As a result of this ability the 
sorghums can produce more dry matter for each unit of leaf area under 
severe climatic conditions than can the corn plant. 
Further details are given in the Journal of Agricultural Research^ 1917. 
PHOCEEDIXGS OF NAT. ACAD. OF SCI., VOL. 3, NO. 6 
