206 
Journal of Agricultural Research 
Vol. VII, No. 4 
Tabi^eXXI .—Correlation of transpiration of small grains with intensity of weather factors 
and with evaporation 
Tempera¬ 
ture. 
Wet-bulb 
depression. 
Evaporation. 
Plant. 
Year. 
Radiation. 
Shallow 
tank. 
Deep 
tank. 
Wind. 
Wheat, Kubanka. 
1914 
0.64 ±0.06 
O. 72±0wO5 
0.88±o. 02 
0. 8s±o. 03 
0. 76 ±o. 04 
0.26 ±0.09 
Do. 
191s 
•57± -08 
. 66± .06 
* 77 ± *05 
•73± .06 
• 5 S± *07 
. 26± .09 
Wheat, Galgalos. 
1914 
. 63 ± .06 
* 73 ± -05 
. 86± .03 
• 86± .03 
• 70± .05 
• 29± .09 
Do. 
1915 
•55± .08 
. 64± . 06 
.8s± .04 
.8i± .04 
.67± .06 
. 25 ± .09 
Oat, Swedish Select.... 
1914 
. 66± .06 
.69± .05 
.86± .03 
• 8s± .03 
. ?8± .04 
. I7± . 10 
Do. 
1915 
• 62± .07 
■ 55 ± • 
. 67 ± .06 
■ 74 ± -05 
• 47 ± *07 
.2I± .09 
Oat, Burt. 
1914 
.69± .06 
• 74 ± -05 
• 89± .02 
. 90± . 02 
• 75 ± *05 
, 2I± . to 
Do. 
1915 
. 66± . 07 
.64± .06 
• 8o± .05 
.89± .03 
.64± .06 
. I5± . to 
Barley, Hannchen. 
1914 
. 61 ± .07 
. 66± .06 
.8s± .03 
. 86± .03 
. 72± .05 
. I 9 ± . II 
Do. 
1915 
• 49 ± .09 
• 63 ± .06 
• 7i± • 06 
. 71 ± .06 
• 49 ± .07 
,I3± .10 
Rye, spring. 
1914 
• 65± .06 
• 73 ± *05 
. 94± *01 
• 9 I± -02 
• 77 ± *04 
. i9± . 10 
Do. 
I 9 i 5 
.6s± .06 
• S 5 ± • 06 
• 73 i -05 
• 79 ± .04 
• 47 ± .07 
.IS± -09 
Mean of 1914 co- 
efficients. 
•65 
• 7 i 
.88 
,87 
• 75 
. 22 
Mean of all co- 
efficients. 
. 62 
.66 
.82 
.82 
.65 
. 21 
Square of mean of 
1914 coefficients. 
.42 
•SO 
•77 
• 76 
• 56 
•05 
Square of mean of 
all coefficients.. 
.38 
•44 
.67 
•67 
.42 
.04 
Wind velocity showed during both years a very low correlation with 
transpiration. 
The relative influence of the various climatic factors on transpiration, 
as expressed by these correlations, may now be considered. If these 
factors are regarded as independent causative elements in transpiration, 
the dependence is shown by the square of the correlation coefficient. 
On this basis the transpiration of the small grains during the two sea¬ 
sons was determined by the different weather factors as follows: Radia¬ 
tion, 38 per cent; temperature, 44 per cent; wet-bulb depression, 67 
per cent; wind, 4 per cent. The fact that the sum of these coefficients 
exceeds unity is the result of intercorrelation among the weather factors. 
The association of the transpiration of the small grains with evaporation 
(shallow tank) is 67 per cent; or the same as with wet-bulb depression. 
The evaporation from the deep tank shows an association of 42 per cent 
with transpiration. 
MiluET, Corn, and Sorghum. —The correlation of the transpiration of 
millet, corn, and sorghum with the several climatic factors is given in 
Table XXII. As in the case of the cereals, the coefficients are higher 
for 1914 than for 1915. The correlation coefficients of the transpiration 
of these crops with the intensity of the various weather factors show the 
same relationships disclosed in the case of the cereals. The highest 
correlation is obtained with wet-bulb depression and with the evapora¬ 
tion from the shallow tank. A somewhat lower correlation is obtained 
in the case of temperature, radiation, and evaporation (deep tank), 
which are correlated with transpiration nearly equally. Wind shows as 
before a very low correlation with transpiration. 
