FREEZING INJURY OF SEED CORN 
T. A. KIESSELBACH AND J. A. RATCLIFF 
INTRODUCTION 
Injury to corn for seed purposes by freezing* in the fall is 
of frequent occurrence in Nebraska and thruout much of the 
corn producing area of the world. The underlying* causes of 
such injury may be (1) late maturity and (2) abnormally early 
freezing* weather. Late maturity may result from (1) late 
planting, (2) planting of unadapted varieties, and (3) peculiar 
weather conditions which do not favor early ripening*. Undue 
early freezing* may work similar injury to corn that would 
possess strong* vitality under normal weather conditions. When 
subjected to a severe frost, immature corn suffers a partial or 
total loss of genninative power. 
The object of the investigations in this bulletin has been 
to determine the conditions under which freezing injury may 
occur to seed corn: to indicate, if possible, the vital changes in 
the embryo resulting in such injury: and to point out ways by 
which seed corn of strong vitality and satisfactory yielding 
capacity may be obtained. 
CHARACTER OF THE CORN EMBRYO AND PROCESS OF 
GERMINATION 
The relation of the embryo to the remainder of the kernel 
of dent corn may be seen in Figures 1 and 2, which are vertical 
and cross sections respectively. The starchy and horny endosperm 
may be distinguished surrounding* the embryo, which consists 
of the plumule, primary root, and seutellum. When placed 
under heat and moisture conditions proper for germination, 
enzymes are secreted by the seutellum of a viable corn kernel, 
which convert the food materials stored in the endosperm into 
forms which may be used for nourishing the young plant. 
In Figure 3 the pericarp or seed coat of a germinating 
kernel has been removed to show the development which took 
place during 35 hours of favorable germination conditions. The 
root develops more rapidly than the stem. 
The effect of 20 hours additional germination is shown in 
Figure I. Three secondary roots have started growth from the 
base of the plumule. 
