Treatment of Cotton Seed 
19 
TABLE III 
Germination of Cotton Seeds at Different Temperatures (100 Seeds in Each Lot). 
Lot 
No. 
Temp, of 
Per Cent of Germination After Hours Indicated 
Av. Length 
of Radicle 
No. Seed- 
Deg. C. 
26 
41 
50 
64 
114 
at end of 
64 hrs. mm. 
lings 
Measured 
1 
15 
0 
0 
1 
31 
OO 
•'T* 
None 
o 
20 
2 
61 
89 
95 
96 
over 2 mm. 
16.8 
96 
3 
25 
11 
63 
85 
94 
94 
17 .1 
97 
4 
30 
64 
97 
99 
99 
32 .6 
99 
5 
35 
32 
66 
84 
91 
91 
99 .1 
65 
6 
40 
0 
0 
0 
0 
0 
Table III, which presents the data obtained in this experiment, shows that, 
when judged by promptness and completeness, germination was decidedly 
most satisfactory in the lot held at 30° C. Very good and practically equal 
germination occurred in the two lots held at 20 and 25°, but these tem¬ 
peratures are obviously less favorable than 30°. At 35° germination was a 
little more prompt but less complete than at 20 and 25°. Sprouting was 
very slow at 15° and did not occur at all at 40°. When one compares the 
values found for the average length of the radicles, the different lots are 
again found to fall in the order given above indicating the relation of 
temperature to germination. The average length of the radicles of lot 4 
was 32.6 mm., that of lot 5 was 22.4 mm., and that of lots 2 and 3 were 
1 16.8 and 17.1 mm. The temperature of 35° is unfavorable for survival and 
continued growth of the seedling after germination. This is indicated by 
the fact that the seedlings die and decay much earlier at this than at lower 
temperatures. By the end of the 64 hour period in the germinator, 26 of 
the 91 seedlings had decayed to the extent that they were not used in ob¬ 
taining the measurements. 
! EFFECT OF TEMPERATURE ON THE DEVELOPMENT OF ANTHRACNOSE 
ON SEEDLINGS 
Three tests were made to determine approximately the most favorable 
temperature for the development of anthracnose on cotton seedlings growing 
on moist blotting paper in test tubes. In the first test, disease-free seed 
of the Dixie variety were inoculated with a suspension of conidia and put 
into test tubes to germinate. One lot of 19 tubes was placed in each of four 
incubators set to run at temperatures of 20, 25.5, 30.5, and 35° C. In the 
second test, disease-free seedlings which had grown in test tubes for 13 
days and which had reached a length of 5 to 6 cm. were inoculated by atomiz¬ 
ing them with a suspension of conidia. They were then separated into 4 
groups of 10 seedlings each and placed in incubators at temperatures noted 
above. In a third test, three lots of six-day old seedlings were atomized 
with a suspension of conidia and put to germinate at 18-25° (18° for 18 
hours, 25° for 6 hours), 25.5, 30, and 33° C. Tables IV and V present the 
data derived from these three experiments. 
