TRANSPIRATION AND PHOTOSYNTHESIS IN CORN 



155 



series were intermingled in such a manner that the plants of any 

 one series would not be subjected to conditions varying from 

 those of the others. When an experiment was completed the 

 plants were severed at the crown, and tracings made of them 

 upon paper. They were then steamed to stop the respiratory 

 processes and placed in a drier where they remained until they 

 had attained a constant weight. The area of the leaves was 



Fig. 3. One potometer from each soil saturation series. Plants between six 

 and seven weeks old. The dry culture is on tjie left, the medium in the middle 

 and the wet on the right. 



then determined by means of the leaf tracings and a planimeter. 

 The dry weight of the plants without the roots was obtained, 

 and this datum was used in the calculation of the water require- 

 ment of the crop. 



The relation between the day and night transpiration is shown 

 in Table 2 and figure 4. It will be noted that the amount trans- 

 spired during both day and night periods show the same rela- 

 tion to the degree of soil moisture, i.e., the plants grown in the 



