LABORATORY TESTS ON EFFECT OF HEAT ON SEEDS OF 
NOBLE AND SILVER FIR, WESTERN WHITE PINE, AND 
DOUGLAS FIR 1 
By J. V. Hofmann 
Forest Examiner, Wind River Forest Experiment Station, Forest Service, United 
States Department of Agriculture 
To test the ability of the seed of noble fir (Abies nobilis ) and silver 
fir (A. amabilis) to withstand the effects of forest fires, samples of 
seed were subjected for 10 hours each to dry heat of varying temper¬ 
atures from 100° to 300° F. and to moist heat of 100° to 240°. The 
samples consisted of 225 seeds for each test. The moist condition 
was produced by keeping water in the heating oven to maintain the 
air as near the point of saturation as possible. 2 
Duplicate tests with Douglas fir (.Pseudotsuga taxifolia) and 
western white pine (Pinus monticola) were made at the same time. 
After heating, 25 seeds were taken from each sample for micro¬ 
scopic examination, and the remaining 200 seeds were sown in the 
nursery in drills, a separate sample in each drill. 
The seeds for these germination tests were sown in the nursery at 
the end of August. A little germination appeared in the fall of that 
year, but most of it occurred during the following season. The 
results are shown in Table I. 
Table I. — Total germination from samples of 200 seeds each of noble, silver, and 
Douglas fir, and western white pine heated for 10 hours 
DRY HEAT 
Temperature 
r F.) 
Noble fir 
Silver fir 
Douglas 
fir 
Western 
white 
pine 
Number 
Number 
Number 
Number 
100 . ..... 
32 
3 
128 
174 
140_________ 
0 
1 
124 
191 
160........ 
9 
o 
123 
157 
180......... 
3 
o 
146 
167 
200 _______ 
0 
o 
1 
4.V* 
47 
220 ........ 
1 
o 
o 
o 
240_________ 
0 
o 
0 
0 
Not heated....... 
4 
3 
no 
188 
MOIST HEAT (AIR SATURATED) 
100 ........ . 
34 
o 
130 
167 
140_ _ _ __ _ 
11 
16 
120 
165 
160_ _ _ _ _ _ _ _ _ 
0 
0 
48 
97 
180. . . . . . . .. 
0 
o 
0 
o 
200 ... . ..... 
0 
0 
0 
o 
220 ...... 
0 
0 
0 
0 
240_ ________ 
0 
0 
0 
0 
Not heated ___ _ _ _ 
4 
3 
no 
188 
1 Received for publication Oct. 28, 1924; issued September, 1926. 
* For heating in moist air above 249° a pressure oven is required. 
Journal of Agricultural Research, Vol. XXXI, No. 2 
Washington, D. C. July 15, 1925 
Key No. F-23 
59837—25f-7 
097) 
