38 Nebraska Agricultural Exp. Station, Research Bui. 6. 
FACTORS INFLUENCING TRANSPIRATION IN FACT. 1 
The phenomenon of transpiration or evaporation from plants 
is subject to many influences. Some of these are very profound 
in their effect, while others are comparatively insignificant. In 
the following outline is given a rather inclusive list of these factors. 
They are either environmental in nature or inherent plant charac- 
ters. Space will not be taken in this bulletin to discuss each of 
these. However, the experimental data with discussions which 
follow concern most of these influences that are important. 
These footnotes refer to the table on the preceding page. 
1 This list of investigators is complete so far as the writer has been able 
to determine, and there are probably not many omissions. 
2 Briggs and Shantz tested over 100 different crops and varieties, these 
in the table being merely representative, and planted respectively at the 
rates indicated. The crops were harvested immature in several tests. 
3 Daszewski gives a table in which Wilm's (1899) data with potatoes are 
reduced to dry weight. He also gives the composition of the crop. 
4 Deherain. The difference between seepage water and rainfall was 
regarded as the amount used by the crop. 
6 Heinrich grew his plants in nutrient solution without soil or sand. 
6 King partly excluded the rain in 1894. He also tested barley, oats, 
and peas. 
7 Khankhoje harvested some plants at an earlier stage to compare with 
mature plants. 
8 Leather tested wheat, barley, oats, linseed, sarson, peas, gram, maize, 
uar, rice, murwa, kodo, rahar, and guar. 
9 Liebscher mentions damage from an overabundance of rain, so his 
pots probably stood in the open. 
10 Marie-Davy. In 1876, part of the pots were exposed to rain and part 
were not. Apparently correction was made for the rainfall. In 1874 and 1875 
only the yield of grain is given, while in 1876 the weights of stems were 692- 
1,065 grams, and the grain weights were 262-474 grams. Only the large 
potometers were used in 1875 and 1876. 
11 Pfeiffer, et al., used an unsatisfactory method for correcting evaporation. 
12 Schroeder. Evaporation was not very satisfactorily prevented in 1893. 
13 Seelhorst apparently grew his plants outdoors and moved them into a 
shelter at time of rain, altho this is not definitely stated. 
14 Sorauer tested a number of additional species, but the methods are so 
faulty as not to be applicable. Most of Sorauer's tests must be included with 
the seedling stage. 
15 Widtsoe. His illustrations indicate that the soil was much overcropped 
with corn. 
16 Wilms based the transpiration on green weight of tubers, but this 
was reduced to dry weight by Daszewski in 1900. 
17 Wollny tested nine varieties in all, including corn, barley, oats, millet, 
buckwheat, peas, rape, mustard, and sunflowers. The evaporation was almost 
prevented by means of a cover, but bare pots were used for correction. Wollny 
states that the rain was excluded by means of covers which had only a small 
hole in the center for the plant. Without sealing the opening about the plant, 
it is possible by this method that rain is conducted down the outside of the 
plant into the pot. 
Contrasted with "Factors influencing transpiration determinations 
with rooted plants in pots as sources of experimental error," — p. 27. 
