18 
1ST. C. Experiment Station 
table II 
Effect of Temperature on The Growth of Glomerella Gossypii on Nutrient 
Agar in Petri Dishes. (Increasing Abundance of Mycelium is Indicated 
by Number of f Marks. The Data Presented Represent The 
Average of Two Colonies in Each Case). 
Exp. 
No. 
Temp. 
Deg. 
C. 
Diam. 
of Colony in mm. 
Relative abundance at 
end of 4 Days 
1 da. 
2 da. 
3 da. 
4 da. 
6 da. 
Aerial 
Mycelium 
Mycelium 
in Sub¬ 
stratum 
Conidia 
1 
21 
No 
5.5 
16.5 
26.5 
t 
t 
t 
growth 
1 
26 
4.0 
19 .0 
30.5 
45.0 
ttt 
tt 
ttt 
1 
30 
5 .5 
19.5 
30.0 
44 .5 
tttt 
ttt 
t 
1 
34.5 
No 
No 
No 
No 
growth 
growth 
growth 
growth 
. 2 
25 
14.5 
25.0 
41 .0 
61.0 
ttt 
tt 
tt 
2 
27.5 
15.0 
28.5 
40.0 
58.0 
ttt 
ttt 
ttt 
2 
30.5 
16.5 
27.5 
38 .5 
57.0 
tttt 
tttt 
+ 
2 
33 0 
8.5 
10.0 
15.0 
22.0 
tttt 
tttt 
t 
A study of Table II, which presents the data of this experiment (Exp. 1), 
shows that temperatures of 26 and 30° C. are about equally favorable for 
growth with a possible slight balance in favor of 30°. Growth was less 
abundant at 21° C. and nil at 34.5° C. A temperature of 26° was most 
favorable for conidial production. A repetition of this test using potato 
glucose agar gave results concordant with those of the first test. The 
results of a second experiment which was similar to the first in every detail 
except that the ovens were maintained at temperatures of 25, 27.5, 30.5, and 
33° C. are also presented in Table II. This test (Exp. 2) shows that only 
negligible differences in growth occurred at temperatures of 25, 27.5 
and 30.5° C. Much less growth took place at 33° C. Conidial formation was 
much better at the two lower temperatures. 
The tests described above may be summarized by stating that except 
for the highest, growth occurred at all temperatures used and was greatest 
in the range from 25 to 30.5. It would seem that with a given lot of 
inoculated seed the disease should develop most rapidly and on the greatest 
number of seedlings within this range of temperature. 
EFFECT OF TEMPERATURE ON GERMINATION OF COTTON SEED 
In order to determine what are suitable temperatures for germination of 
cotton seed, the following experiment was performed. Six hundred seeds 
were shaken in a quantity of sterile tap water until the fuzz was thoroughly 
wetted through to the seed coat. These seeds were then divided into 6 
lots of 100 seeds and each lot was placed on moist blotting paper in a 
separate, covered, glass germinator. The germinators were kept at tem¬ 
peratures of 15, 20, 25, 30, 35 and 40° C. The percentage of germination was 
ascertained at short intervals, and the hypocotyls were measured and the 
average length computed at the end of 64 hours. 
