DAILY VARIATION OF THE CARBOHYDRATES IN THE 
LEAVES OF CORN AND THE SORGHUMS 1 
By Edwin C. Miller 2 
Plant Physiologist, Department of Botany , Kansas Agricultural Experiment Station 
INTRODUCTION 
In a comparative study of the physiological functions of com ( Zea 
mays) and the sorghums (. Andropogum sorghum), it was thought advis¬ 
able to make some observations on the variations of the carbohydrates 
in the leaves of these plants during a 24-hour period. It was considered 
that any data obtained in a study of this kind would be of value not only in 
interpreting the different behavior of these two types of plants when 
grown under severe climatic conditions, but also in helping to gain a 
better general knowledge of the fundamental physiological processes of 
agricultural plants. The observations reported in this paper were made 
upon plants growing at Garden City, Kans., in 1916 and 1917, and at 
Manhattan, Kans., in 1919. 
HISTORICAL 
The basis of our knowledge of the carbohydrates of the leaves was laid 
by Sachs ( 12 , 13 , 14 ) 3 when he proved that the appearance of starch in 
the chloroplasts is a direct outcome of the fixation of carbon under the 
influence of sunlight and chlorophyll. He further stated that starch is 
the first visible product of carbon assimilation and that it is translocated 
from the leaves in the form of sugar. Kayser (8) found both cane sugar 
and reducing sugar in the leaves of the beet, grape, potato, and onion 
and succeeded in separating cane sugar in the crystalline form from the 
leaves of the grape. Girard (7) found that the amount of cane sugar in 
the leaves of the beet increased during the day, but that the amount of 
hexoses remained approximately constant. Schimper (15) concluded 
that glucose formation precedes starch formation in the leaves and that 
starch is formed from glucose when its concentration exceeds a certain 
maximum, which differs in different plants. Meyer (9) observed that 
certain plants form little or no starch in their leaves and that when 
starch is found in leaves the amount of sugar present is relatively low, 
while when starch is absent the sugar content is relatively high. 
Brown and Morris (/) in their classical work on the carbohydrates of the 
leaves of nasturtium considered that the dextrose and laevulose present 
in the leaves are more readily accounted for as the products of the 
hydrolysis of cane sugar than as its precursors. On account of the relative 
amount of cane sugar found in the leaves and the manner in which it 
1 Accepted for publication Dec. 18, 1923. Contribution from the Department of Botany, Kansas Agri¬ 
cultural Experiment Station, paper No. 207. Published with the approval of the Director. 
2 The carbohydrate determinations were made by the Department of Chemistry, Kansas Agricultural 
Experiment Station, the funds for the work being furnished by the Department of Botany. Acknowl¬ 
edgments are due Prof. W. L. Latshaw, under whose supervision the chemical analyses were conducted. 
8 Reference is made by number (italic) to “Literature cited,” p. 807-808. 
Journal of Agricultural Research, 
Washington, D. C. 
( 7 »s) 
Vol. XXVII. No. :o 
Mar. 8,1924 
Key No. Kans.-40 
