COMPARATIVE TRANSPIRATION OF CORN AND THE 



SORGHUMS 



By Edwunt C. MitLER, Associate Plant Physiologist, Department of Botany, Kansas 

 Agricultural Experiment Station, and W. B. CofFman, Graduate Student, Kansas 

 Agricultural College 



INTRODUCTION 



In connection with the investigations of the water relations of corn. 

 {Zea mays) and the sorghums {Andropogon sorghum) previously reported 

 by the senior writer/ it was thought advisable to study the daily transpira- 

 tion of these plants. A knowledge of the rate of transpiration of these 

 plants under the same environment is essential in order to determine the 

 factors that are concerned in their relative ability to withstand severe 

 climatic conditions. A study of the rate of transpiration at various 

 stages of the development of these plants should help to determine 

 whether the ability of the sorghums to withstand severe climatic con- 

 ditions better than the corn plant is aided by the pov/er of the sorghums 

 to retard the rate of water loss from their leaves or by the fact that they 

 have a much smaller leaf surface exposed for the evaporation of water 

 The experiments herein reported were conducted during the summers of 

 1 91 6 and 191 7 at the State Branch Experiment Station at Garden City, 

 Kans. 



EXPERIMENTAL METHODS 



CULTURAL METHODS 



The plants used in these experiments in 191 6 were Pride of Saline com, 

 Dwarf Blackhull kafir. Dwarf milo, and Blackhull kafir. In 191 7 in 

 addition to these, Sherrod's White Dent corn, Freed's White Dent com. 

 Red Amber sorgo, Freed's sorgo, and feterita were used. These plants 

 were grown in large galvanized-iron cans. The cans were 24 inches in 

 height, with a diameter of 15 inches, and under the conditions of these 

 experiments contained about 120 kilos of soM. The soil was worked 

 through a X-inch mesh screen and was thoroughly tamped in the cans. 

 The soil used in 191 6 had a moisture content of 18 per cent and a wilting 

 coefficient of ii.i, while the moisture content of the soil used in 191 7 was 

 22 per cent and had a wilting coefficient of 15.1. Thus, for both seasons 

 there was a difference of approximately 7 per cent between the water 



' Miller, E. C. comparative study of the root systems and leaf areas of corn and the 

 SORGHUMS, /n Jour. Agr. Research, V. 6, no. 9. p. 311-332. 3 fig- pi- 38-44- 1916. Literature cited, p. 331. 



RELATIVE WATER REQtnREMENT OF CORN AND THE SORGHUMS. In Jour. Agr. Research, v. 6, no. 



13. P- 473-4S4. I fig-. Pl- 70-72- 1916. 



D.MLY V.\RIATI0N OF WATER AND DRY MATTER IN THE LEAVES OF CORN AND THE SORGHUMS. In 



Jour. Agr. Research, v. 10, no. i, p. 11-45, 10 fig-, pl- 3- 1917. 



Journal of Agricultural Research. Vol. XIII, No. 11 



Washington, D. C. June 10, 191S 



ny Key No. Kans.-i3 



56113°— 18 5 (579) 



