JOURNAL OF ACKM1AL RESEARCH 
Vol. XXVII Washington, D. C., January 12, 1924 No. 2 
ANCHORAGE AND EXTENT OF CORN ROOT SYSTEMS 1 
By James R. HolberT, Agronomist, and Benjamin Koehler, Assistant Pathologist, 
Office of Cereal Investigations, Bureau of Plant Industry, United States Department 
of Agriculture 2 
INTRODUCTION 
Results from preliminary experiments indicate that there are funda¬ 
mental differences in the root systems of various inbred strains of corn. 
The object of the present paper is (1) to call attention to a plant-pulling 
machine which was designed for these studies and (2) to point out a 
few significant differences in the root systems of the inbred strains that 
were included in the experiments. 
MATERIALS AND METHODS 
A plant-pulling machine (PI. 1) was designed to measure the resist¬ 
ance of individual plants or hills of corn to a vertical pull. The essential 
features of this machine are a cross beam with three axes which divide 
the beam into two parts, so as to make a lever of the second class. 
Each axis consists of a knife edge turning in a clevis. The distal axis 
is attached to a spring balance which registers the pulling resistance to the 
tenth of a pound. The clevis of the other end of the beam is supported 
by a block and tackle, the rope being pulled by winding it on a 2-inch 
drum. Two thicknesses of strong cotton webbing such as are used for 
trunk straps were attached to the third clevis, and these were attached 
to the base of the corn stalks by a suitable hitch. 
The inbred strains of corn, except where indicated otherwise in the 
tables, had been selfed five and six years. The strain, designated as 
“good,” not only possessed the ability to stand erect under adverse 
weather conditions, but was exceptionally good in general vigor, chlo¬ 
rophyll development, and resistance to fungus diseases, including root- 
rot and smut. The strain susceptible to rootrot was equally good in 
general vigor, and the leaves were free from leaf spotting and other 
chlorophyll deficiencies, but plants of this strain lodged badly during 
windstorms. At no time did the leaves of either of the above strains 
show any tendency to wilt during early or mid-season periods. Leaves of 
the strain susceptible to leaf firing invariably wilted during any dry, 
hot period in July. Severe wilting of the leaves was followed by a dying 
of portions of those leaves. 
The field data were secured from plats having a perfect stand of one 
plant every 22 inches in rows 42 inches apart. The plants grown in the 
greenhouse were spaced 18 inches each way. 
The significance of differences in means was determined by “ Student’s ’* 
method, 3 wherever that method could be applied. Differences with odds 
of 30:1, were considered significant. 
1 Accepted for publication Nov. 19, 1923. 
2 The investigations reported in this paper were conducted in cooperation with the Illinois Agricultural 
Experiment Station and Funk Bros. Seed Co., of Bloomington, Ill. 
a The probable error op a mean. In Biometrika, v. 6, p. 1-25. 1908. (Signed by Student.) 
Journal of Agricultural Research, 
Washington, D. C. 
(71) 
Vol. XXVII. No. 1 
Jan. 12,1924 
Key No. G-349 
73431—24-1 
