262 
Journal of Agricultural Research 
Vol. XXXI, No. 3 
Notes on terminal-bud formation and on second growth were 
taken September 3 and November 6. 
After the close of the growing season weights and measurements 
of the top and root development of the seedlings, taken from 25 
plants arbitrarily selected from each bed, were recorded. 
RESULTS 
A general correlation of soil temperature and germination of seeds 
is established. When the soil temperatures given in Figure 1 and 
the period of best germination in Table I are related, definite relations 
between soil temperature and germination are seen, although specific 
instances differ. The periods of best germination for the sowings 
of March 25 and April 4 are shown to be later than those for the 
sowings of April 13 and April 25. This condition emphasizes the 
danger of early spring sowing because of the long dormant period 
of the seed and the consequent exposure to damping off. The 
month of May was unfavorable to germination, and the periods of 
best germination were after the soil had warmed. Likewise the best 
germination period of the fall sowing came when the soil was warmest 
in the latter part of April and early May. The general indications 
of the spring sowings are that germination does not proceed at its 
best until the soil temperature is 70° F. or warmer to a depth of 
6 inches. Surface temperature may be higher, but a cooler soil 
below the surface causes rapid and extreme fluctuations at the 
surface and the seed does not get the benefit of a high enough tem¬ 
perature for good germination. 
The fall sowing resulted in the greatest germination and also the 
highest percentage of survival, as shown by Table I and Figures 2 
and 3. 
Table I .—Effect of time of sowing on germination and bud maturity 
Time of sowing 
Number of 
days before 
2-week periods of best 
germination 
Total 
germina¬ 
tion per 
Percentage of buds 
mature 
germina¬ 
tion 
square 
foot 
Sept. 3 
Nov. 6 
Nov. 16,1917. 
At least 30 
Apr. 23-May 6_ 
Number 
52.5 
Per cent 
88 
Per cent 
100 
Mar. 25,1918. 
days in 
spring. 
73 
June 20-July 3__. 
20.8 
73 
100 
Apr. 4, 1Q1R 
64 
June 2l-July 4_. 
28.2 
85 
100 
Apr. 13,1918.. 
58 
June 17-June 30. 
24.9 
71 
100 
Apr. 2fi, 1018 
53 
.do. 
23.8 
23 
100 
May 4, 191R 
51 
June 24-July 7_ 
29.1 
24 
100 
May 20, 1Q1R 
35 
_do_ 
28.2 
6 
98 
May 31,1918. 
38 
July 15-July 28. 
27.2 
11 
95 
The losses were due almost entirely to damping off, practically all 
those indicated by the cultures being caused by Pythium debaryanum . 
Rhizoctonia sp. was found in a few cultures later in the season. 
Figure 2 shows that germination proceeded quite uniformlv in each 
bed after it began, with the exception of the fall sowing. Although 
weekly records vary, all of the spring sowings were quite uniform m 
final germination, with slightly wider differences in survival, as 
shown in Figure 3. The dormant period of the seed in the seed bed 
was very much shorter in the later sowings. This is an important 
factor, as it reduces the period of exposure to damping off. The fall- 
