1184 
Journal of Agricultural Research 
Vol. XXXI, No. 12 
decreased in germination only slightly or not at all. Table I shows 
very clearly the pronounced effect of aging on the germination of 
frozen wheat, the germination being at first relatively low, increasing 
to a maximum, and then decreasing, so that at the end of a year the 
germination is again relatively low. The germination of the wheat 
which was more mature at the time of frost was less affected by 
freezing than was the more immature wheat. It would seem from 
an examination of Table I that if frosted wheat is to be used for seed 
it should be tested for germination immediately before seeding. 
Comparisons of the effects produced by subjecting seeds to freezing 
temperatures should include aging experiments. 
Kiesselbach and Ratcliff (9) studied the effect on germination of 
subjecting immature corn to freezing temperatures. Their results 
show clearly that at a given moisture content the injury increases 
as the freezing temperature is lowered, and that “ death from freezing 
is directly related to the moisture content of the kernel and also 
to the duration of the exposure to cold. ” 
The wheat used in this investigation was subjected to freezing 
temperatures considerably lower than wheat would normally encounter 
in the field. These low temperatures were chosen intentionally, 
for the reason that if no effect was produced under these conditions 
then no effect would be expected under less severe ones. The results 
indicate the desirability of investigating the effect of less severe 
freezing temperatures. 
Attention is called to the almost complete germination of the 
nonfrozen wheat at all of the stages of development studied. Even 
when the kernel was only approximately 13 days old germination 
was practically complete. The investigations oi Harlan and Pope 
(i 6 ) on the germination of barley harvested at different stages of growth 
are of interest in this connection. These investigators hand-polli¬ 
nated Hannchen barley so that they knew the exact age of the kernel 
to within one hour. They found no germination on the fourth day, 
but on the fifth day 9 out of 10 kernels germinated. The dry matter 
content of the Hannchen barley at 6 days of age was given as about 
5 mgms. Kiesselbach and Ratcliff (9), in studying seed corn pro¬ 
duction, found that “the power of germination is attained in about 
20 days after fertilization. , 
The germination tests carried out by the ice-box method December 
21, 1923, gave only slightly different results from the alternating- 
temperature method. 
Pnotographs of the germinated kernels from the test of December 
21, 1923, using the alternating-temperature method for samples 
131 and 132, are given in Plate 2; for samples 137 and 138, in Plate 
3; and for samples 149 and 150, in Plate 4. These plates give an 
indication of the probable strength of the plant produced. There 
is apparently a greater development in the more mature samples. 
