UNITED STATES DEPARTMENT OF AGRICULTURE 
k BULLETIN No. 1062 
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kgr Contribution from the Bureau of Plant Industry £\| 
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WM . A. TAYLOR, Chief, in cooperation with Purdue Univer- 
sity Agricultural Experiment Station. 
Washington, D. C. PROFESSIONAL PAPER April 22, 1922 
RELATION OF THE CHARACTER OF THE ENDO- 
SPERM TO THE SUSCEPTIBILITY OF DENT 
CORN TO ROOT ROTTING. 
By John F. Trost, Assistant Pathologist, Office of Cereal Investigations, Bu- 
reau of Plant Industry, and the Department of Botany, Purdue University 
Agricultural Experiment Station, 
CONTENTS. 
Page. 
Ear classification based on starchi- 
ness 
Relation of endosperm character and 
ear infection 
Page. 
Relation of kernel starchiness to 
pathological performance 4 
Susceptibility of disease-free seed 
ears 5 
Summary 7 
EAR CLASSIFICATION BASED ON STARCHINESS. 
Early in the course of investigations of the root, stalk, and ear 
rots of corn, differences were observed in the amount of starch in 
the various ears from which kernels were being germinated to 
determine the extent and character of seed-ear infections. These 
differences were noticeable not only among different varieties, but 
often equally so among the individual strains within a single variety. 
It seemed important to determine what physical characters of 
the ear or kernel, if any, might be used in recognizing and eliminat- 
ing infected seed ears. Obviously, such a procedure would be val- 
uable in reducing the necessity for a detailed germination test of 
each ear. 
The ears were classified on the basis of the endosperm. The 
starchy endosperm appears opaque when the kernel is held up to the 
light, but the portion containing horny endosperm is more or less 
translucent. Six degrees or types of starchiness were recognized and 
80451—22 
