JOURNAL OF AGEICDL TPRAL RESEARCH 
Vol. XXI Washington, D. C., April 15, 1921 No. 2 
SEED-COAT INJURY AND VIABILITY OF SEEDS OF 
WHEAT AND BARLEY AS FACTORS IN SUSCEPTIBILITY 
TO MOLDS AND FUNGICIDES 1 
By Annie May Hurd 
Assistant Pathologist, Office of Cereal Investigations, Bureau of Plant Industry, United 
States Department of Agriculture 
SEED-COAT INJURY AND VIABILITY OF SEEDS AS FACTORS IN 
SUSCEPTIBILITY TO SAPROPHYTIC FUNGI 
Saprophytic fungi, infesting both soil and seed, constitute an important 
group of enemies to successful wheat and barley culture. The present 
investigation is (i) a study of some of the factors, especially the physical 
condition of the seed coat, which enable these saprophytes to attack the 
seed, and (2) the relation of mechanical injuries sustained by the seed 
coat to seed-treatment injury. The fungi used for the experimental 
infections were Penicillium sp. and Rhizopus nigricans . Penicillium 
causes serious losses where soil conditions favor its development and in¬ 
fection. Penicillium and Rhizopus are the two omnipresent molds which 
cause much trouble in blotter germinations in the laboratory. Rhizopus 
was not found attacking seeds in storage or in the soil. 
It was noticed early in the study of germinating wheat in blotters that 
neither of these fungi was ever found on healthy, unbroken seeds, but that, 
if the seed coats were broken over the endosperm and germinated under 
nonsterile conditions, the seeds invariably were badly attacked. Neither 
fungus, however, attacked seeds whose only injury was a break in the coat 
over the embryo (PI. 13). 
Following these observations, experiments were planned to determine 
whether and under what conditions wheat seeds with unbroken coats or 
with the coat injured only over the embryo were immune from artificial 
infection with heavy inoculations of Penicillium and Rhizopus spores. 
The experiments were with hand-thrashed Early Baart wheat, injured 
with a dissecting needle and sown on blotters thickly sprinkled with 
1 This investigation was carried oil in cooperation with the California Agricultural Experiment Station. 
The writer acknowledges with sincere gratitude the helpful suggestions of Profs. J. W. Gilmore and W. W. 
Mackie. of the University of California, and Dr. H. B. Humphrey, of the United States Department o* 
Agriculture, during the progress of this investigation and the preparation of the report. 
Journal of Agricultural Research. 
Washington, D. C. 
Vol. XXI, No. a 
Apr. 15. 1921 
