journal of maim research 
Vol. XIV Washington, D. C., September 16, 1918 No. 12 
RESISTANCE OF SEEDS TO DESICCATION 
By George T. Harrington, Scientific Assistant , Seed Laboratory, and William 
Crocker, Plant Physiologist , Drug-Plant , Poisonous-Plant , Physiological , end 
Fermentation Investigations , Bureau of Plant Industry, United States Department of 
Agriculture . 
INTRODUCTION 
The question of the resistance of seeds to extreme drying probably 
first came into prominence as a result of the use of artificial desiccation 
to hasten afterripening, as reported by Hotter, Nobbe, Atterberg, Kiess¬ 
ling, and others. The drying was usually done in drying ovens, and the 
temperatures used frequently were not such as to reduce the moisture 
content of the seeds below 5 or 6 per cent. Sometimes, however, when 
higher temperatures were used, the moisture content fell considerably 
lower than this, and in such cases the germination was often lowered. 
The question, of course, arises whether the injury comes from the loss 
of moisture or as the effect of the high temperatures used. 
HISTORICAL REVIEW 
Schroeder 1 dried barley and wheat for 12 weeks over sulphuric acid. 
At the end of this time they contained only 1 to 2 per cent of moisture, 
but nearly all germinated. Nobbe 2 reduced the water content of rye 
to 1.2 per cent by drying it at 8o° C. with very little effect upon subse¬ 
quent germination. More severe drying by heat seriously injured the 
germination of rye, and less severe drying had an injurious effect upon 
wheat and oats. About the same time Ewart, 3 working with seeds of 
wheat, com, barley, peas, haricots, hemp, squash, rape, and sunflower, 
which he dried in a vacuum desiccator at 37 to 38° C., concluded that it 
is impossible to reduce the percentage of water held by even the most 
resistant seeds to lower than 2 or 3 per cent of their dry weight without 
injuriously affecting their vitality. Ewart's hypothesis was that ex¬ 
cessive drying so changed the dormant protoplasm that upon being 
remoistened it was unable to reestablish the molecular groupings essential 
for normal vital activity. 
1 Schroder, G. uber die austrocknungsfahigkeit der pflanzen. In Untersuch. Bot. Inst. 
Tubingen, Bd. 2, Heft r, p. 1-52. 1886. 
3 Nobbe, E. uber kunstuche getreidetrocknung mit bezugaufdie keimfahigkeit. In Mitt. 
Deut. Landw. Gesell., Jahrg. 12, Stuck 14, p. 185-186. 1897. 
* Ewart, A. J. additional observations on the vitality and germination op seeds. In Proc. 
and Trans. Liverpool Biol. Soc., v. 10, 1895/96, p. 185-193, 5 pi. 1896. 
( 525 ) 
Journal of Agricultural Research, 
Washington, D. C., 
Ph 
Vol. XIV, No. ia 
Sept. 16,1918 
Key No. G-154. 
