34 
Journal of Agricultural Research 
Vol. XXVI, No. I 
Table V .—Temperature of the upper surface of the leaves of plants during the day and 
night —Continued 
PART 3 
Time. 
Evapo¬ 
ration. 
Number 
of deter¬ 
mina¬ 
tions. 
Average temperature (°C.) of— 
Air. 
Kafir, Pink. 
Corn, Commercial 
White. 
Turgid. 
Wilted. 
Turgid. 
Wilted. 
Aug. 17: 
Cc. 
8.40 to 8.55 a. m.. 
0.4 
20 
3 °. I 
29. 8 
29. 8 
9.20 to 9.35 a. m.. 
•4 
20 
31-3 
31. 2 
32. 2 
9.55 to 10.05 a. m. 
.6 
20 
33 - 1 
32. 6 
33-4 
11.00 ton.15a.m. 
.8 
20 
34 . 0 
33 - 5 
35 -o 
11.15ton.30a. m. 
•9 
20 
34.3 
33 - 7 
35 - 1 
1.25 to 1.40 p. m.. 
1. 0 
20 
35 -o 
33- 6 
35 - 6 
2.05 to 2.20p. m.. 
1. 0 
20 
35 - 5 
35 -o 
36. 8 
3.10 to 3.25 p. m.. 
1. 0 
20 
35 - 1 
33-8 
35 - 7 
3-30 to 3 - 5 ° P- m - 
i -3 
20 
36. 2 
34 - 8 
36.7 
4.35 to 4-50 P- m - 
1. 0 
20 
35 - 6 
33-8 
35-6 
6-55 to 7.10 p. m.. 
. 4 
20 
29. I 
28. 2 
28.6 
Aug. 18: 
8.30 to 8.45 a. m.. 
•4 
20 
3 1 * 7 
31-9 
32. 6 
9.20to9.35 a. m.. 
• 5 
20 
33 - 2 
33-4 
33-4 
10.00 to 10.15 a.m. 
.8 
20 
34 - 2 
33-3 
36. 2 
11.05 to 11.20 a. m. 
.8 
20 
34.3 
33-5 
37-4 
1.30 to 1.45 p.m.. 
•9 
20 
3 6 -9 
36.3 
39 -0 
2.55 to 3. 10 p. m.. 
1. 1 
20 
35-8 
35 - 1 
38. 1 
3.40 to 3.55 p. m.. 
•9 
20 
33 - 6 
33 - 1 
35-2 
4.10 to 4.25 p. m.. 
.8 
20 
32. 5 
32.4 
34 - 3 
4-35 to 4 - 5 ° P- m •• 
.6 
20 
30 - 7 
30-3 
30 - 5 
6.30 to 6.45 p. m.. 
•3 
20 
28. 0 
2 7 - 5 
27. 7 
7.00 to 7.15 p. m.. 
. 2 
20 
27. 2 
26. 9 
26. 9 
R rt tnn Tf» r» m 
. 2 
20 
26. 2 
26. 0 
26. O 
°*0j Aii.. 
9.15 to 9.30 p. m.. 
. 1 
20 
2^-4 
2 5 - q 
25. 1 
11.05t0n.20p. m. 
. 1 
20 
23.1 
22.7 
22. 8 
11.25ton.40p.rn. 
. 1 
20 
23.0 
22. 8 
22. 8 
Aug. 19: 
1.05 to 1.20 a. m.. 
. 1 
20 
22. 7 
22. 5 
22. 5 
1.25 to 1.40a. m.. 
. 1 
20 
22. 7 
22.3 
22. 5 
20 
21. 2 
20. 8 
21. 0 
3.20 to 3.35 a. m. . 
. 1 
20 
21. 2 
20. 9 
21. O 
ditions upon the temperature of leaves is further shown when their 
temperature is observed from 4 p. m. until twilight and from daylight 
until 8 a. m. The temperature of leaves during these periods is always 
lower than that of the surrounding air and is plainly evident in any of 
the tables where any temperature data on leaves for these periods are re¬ 
corded. During the night, according to our observations, the temperature 
of the leaves is approximately that of the air. Some of the data obtained 
on the temperature of leaves during the day and night are recorded in 
Table V. The behavior of the temperature of corn and milo leaves 
during a 24-hour period is illustrated by graphs in figure 5. The obser¬ 
vations are similar to those of Shreve (it), who measured the temperature 
of the leaves of Parkinsonia microphylla by a calorimetric method. 
She found that the temperature curves of the leaves were below the air 
temperature curves at night and in early morning until about 10 o'clock, 
when the leaf temperature rose above the air temperature, retaining that 
relative position until shortly after noon. 
