Transpiration as a Factor in Crop Production. 
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OUTLINE OF FACTORS INFLUENCING TRANSPIRATION IN FACT. 
A. Atmospheric (or climatic). 
1. Temperature. 
2. Relative humidity. 
3. Wind velocity. 
4. Light. 
5. Radiant heat. (Radiation.) 
6. Composition of air. 
7. Air pressure. 
8. Evaporation rate of free water as a summary expression 
of the climatic factors. 
B. Soil. 
1. Composition. 
2. Available fertility (strength of soil solution). 
3. Available moisture content. 
4. Soil texture. 
5. Soil temperature. 
C. Plant characters. 
1. Root development. 
2. Leaf -area. 
3. Arrangement of leaves. 
4. Structure (especially of leaves). 
5. Dry weight of plant (not a determining but a resultant 
factor). 
6. Density of cell sap (osmotic pressure). 
7. Relative ability to withstand periods of drouth. 
8. Heat generated within plant as result of chemical activity. 
9. Age of plant. 
10. Moisture content of leaf. 
11. Cooling effect exerted upon plant itself by transpiration. 
12. Vital element in the plant. 
(An indirect factor as it affects physical conditions 
within the leaf.) 
13. Disease. 
