UNITED STATES DEPARTMENT OF AGRICULTURE 



j| BULLETIN No. 1062 



jijrr Contribution from the Bureau of Plant Industry T9Cl 



^.J.^* WM. A. TAYLOR, Chief, in cooperation with Purdue Univer- ' 

 ^^ * s> ^"*» 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 Johx 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 starehi- 

 ness 



Relation of endosperm character and 

 ear infection 



Page. 



Relation of kernel starehiness 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 cars were classified on the basis of the endosperm. The 



PChy endosperm appears opaque when the kernel is held up to the 



light, hut the portion containing horny endosperm is more or less 



translucent. Six degrees or types of starehiness were recognized and 



B«451 22 



