43 
Sorghum Simut Investigations 
Dr. D. Elizabeth Marcy has continued the investigations on the 
inheritance of smut resistance in sorghum hybrids. Over a period 
of years, a large amount of data has been obtained on 24 different 
sorghum hybrids. These hybrids were tested for the reaction to 
both the covered smut (Sphacelotheca sorght) and to the loose 
smut (S. cruenta). They represented some crosses between re- 
eH 
sistant varieties, other crosses between susceptible varieties, and a 
third group of crosses between resistant and susceptible varieties. 
Generally, the F,, F,, and F., generations were grown, but for some 
hybrids data were obtained for fourth and fifth generation proge- 
nies. Approximately 50,000 plants have been grown during the 
five year period from 1931 to 1935. The results for 12 of these 
crosses have been written up in final form and presented as the 
thesis for the degree of Doctor of Philosophy at Columbia Uni- 
qerdata son tie 
ee 
versity, and have been accepted for publication. T 
remaining hybrids are now being prepared for publication. 
The sorghum hybrids are stuuitable material for the study of the 
Sorghums are par- 
inheritance of Many mot phological characters. 
ticularly favorable for such studies because of the ae differ- 
ences between the parental varieties used. Accordingly, for all 24 
crosses, records have been taken on various characters, ree 
the color of the glumes and of the seeds. These data have been 
nd have proved to be of considerable interest. At least 
one case Hes in inheritance has been noted. Miss Theresa 
ee i Brooklyn College has assisted in recording much of 
analyzed a 
= 
the data. 
The experiments with the influence of environment on the infec- 
tion of sorghum have been continued, The effects of temperature, 
moisture, and sugar solution have been tested, the same conditions 
being supplied as in 1935. The seedlings were germinated in cups 
of sand, placed in a constant temperature tanks, and temperatures 
Otel oe foe Ue ee ees, 27.5 -and.J0" Ceweredised.s, Thesper 
centage of moisture varied in the different experiments from 10 to 
50 per cent. of the total water holding capacity of the sand. One 
with water, while another set re- 
Qu 
set of seedlings was moistenec 
ceived a 2 per cent. sucrose solution. 
There was no attempt to control temperature or moisture after 
