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L I ; f; A R V 





A STUDY OF THE RELAT. 4N OF SOIL MOISTURE TO 

 TRANSPIRATION AND PHOTOSYNTHESIS IN THE 

 CORN PLANT 



T. G. YUNCKER 



University of Nebraska, Lincoln, Nebraska 



The object of the follo\ving experiments was to determine the 

 relation existing between the amount of transpiration and of 

 photosynthesis in corn plants and the degree of soil moisture in 

 which they were grown. Three degrees of soil moisture were 

 maintained. The amount of transpiration was obtained by con- 

 tinuous weighings of potometers and a record was kept of the 

 water that was used by the plants. The amount of photo- 

 synthesis was determined by measuring the weights of a given 

 unit of area of the plants of the three series of soil moisture at 

 different intervals during the day. The plants were grown in 

 the greenhouses of the University of Nebraska during the fall 

 and winter of 1914-1915 under normal greenhouse conditions. 

 In the progress of this work the writer has become deeply in- 

 debted to Dr. R. J. Pool. 



EXPERIMENTAL METHODS 



Kind of potometers used and their preparation. Two-gallon 

 glazed earthenware crocks such as can be purchased at a crockery 

 store were employed throughout the experiments. These, being 

 glazed, were evaporation proof. A good grade of loam soil was 

 well worked over with a rake and then sifted through a mesh 

 of f in. which gave a very fine grade of loam soil free from lumps 

 and foreign matter. To facilitate the spread of water through- 

 out the entire potometer a layer 3 cm. deep of medium size gi-avel 

 was placed in the bottom of each potometer. One 3 in. unglazed 

 earthenware flower pot (common greenhouse potting pot) was 

 filled with gravel and inverted in each of the potometers. A 



151 



THE PLANT WORLD, VOL. 19, NO. 6, 1916 



