SORGHUM SMUTS AND VARIETAL RESISTANCE 45 
optimum temperature for the germination of the seed was 36° to 
40° C. and that for the spores of the two smuts, 20° to 22° C. The 
highest percentages of infection were obtained between 16° and 30° C. 
Kulkarni concludes that the soil temperature and moisture are 
the determining factors in the occurrence and distribution of the 
sorghum smuts in the Bombay Presidency. The kharif varieties, 
sown in the period of higher rainfall and lower temperature, are 
more severely infected with smut than the rabi sorghums, the latter 
varieties being sown in the drier, warmer season, when conditions 
are more favorable for the rapid growth of the seedlings, whose 
susceptible stage thus is quickly passed over. It also may be noted 
that the kharif jowar consists mainly of varieties of durra, while the 
rabi jowar consists of varieties of shallu. Whether the difference in 
varieties is a factor remains to be determined. 
Kulkarni further states that the amount of sorghum smut is very 
much less in the eastern part of the Bombay Presidency, where there 
is a decrease in the rainfall and an increase in the temperature, as 
compared with the western part. The rarity of these smuts in Sind, 
the Punjab, United Provinces, and Bihar also appears to be dependent 
upon these factors. Kulkarni attributes special importance to soil 
temperature in these Provinces, as the average temperature at 
seeding time is between 32° and 38° C, which is well above the 
optimum temperature for the germination of the spores. 
In a more recent paper Kulkarni (65) records some experimental 
data bearing upon the question. He germinated two sets of seed 
inoculated with spores of SphacelotJieca sorghi, one set at 40° C. and 
the second set at 25° C. After germination the seedlings were 
transplanted to pots and the plants grown to maturity. At the 
higher temperature no infected plants were obtained out of a total 
of 69, while at the lower temperature 35 out of 64 plants were infected. 
Two series of field experiments were also carried out, one in 1918 at 
Pusa, Larkhana, and Poona, and the second in 1920 at Jacobabad 
and Poona. The temperatures prevailing at the three stations in 
1918 during germination were not strikingly different, and fairly 
high percentages of infection were obtained at each. In 1920 no 
infection was obtained at Jacobabad, the temperature during the 
period of germination being 36° to 40° C., while 65 per cent of infection 
occurred at Poona, where the temperature during germination was 
25° C. 
As has been previously stated, the preliminary germination studies 
of susceptible and resistant varieties of sorghum thus far made by 
the writers (Table 13) do not indicate that any striking correlation 
exists between the rate of germination and its behavior when sub- 
jected to smut infection, but that marked differences in germination 
can not be noted in the same variety when grown at various tem- 
peratures. While it may germinate much more rapidly than other 
varieties at one temperature, this does not hold for other tempera- 
tures. As so little is known about the stage at which infection 
occurs, it is possible that the periods at which the measurements 
were made should have been extended so as to obtain greater 
growth. It seems apparent, however, from the studies thus far 
made that there is little correlation between the rapidity of early 
growth and smut resistance or susceptibility. Similar germination 
studies had been made in 1921, using the same varieties. Only 20 
